Repair Hints (for several types of video terminals) .............................................................................. This page is a small part of the Video Terminal information archive, of which the main entry point is http://www.cs.utk.edu/~shuford/terminal_index.html ...Richard S. Shuford ////////////////////////////////////////////////////////////////////////////// General note: Technical information for various electronic devices, including some terminals, had been available in the "PhotoFact" document series published by Howard W. Sams Company 2647 Waterfront Parkway East Dr. Indianapolis, IN 46214-2012 USA voice: +1 317/298-5400 -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- -- A web site with repair advice for video monitors: "Service Engineers Forum" http://www.e-repair.co.uk/index.htm A web site for a parts and component supplier in Kentucky: http://www.radioelectronics.com/ Radio-Electronic Equipment Co, Inc. 480 Skain Ave. PO Box 1209 Lexington, KY 40508 +1 859/255-6661 -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- ---- -- -- Newsgroups: vmsnet.pdp-11 Path: cs.utk.edu!emory!gatech!howland.reston.ans.net!usc!elroy.jpl.nasa.gov !ncar!uchinews!rover.uchicago.edu!frank Message-ID: <1JUN199310352027@rover.uchicago.edu> News-Software: VAX/VMS VNEWS 1.41 Sender: news@uchinews.uchicago.edu (News System) Reply-To: frank@rover.uchicago.edu Organization: Joint Center for Radiation Therapy References: Date: Tue, 1 Jun 1993 16:35:00 GMT From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger) Subject: Re: Help with LA100 power supply In article , mjohnson@charlie.usd.edu writes... > > I was recently given an LA100-PC printer by another PBS station. > Unfortunately, the power supply in this printer has grown weak and > no longer has enough oomph to fire all or most of the pins in the > printhead at once. This causes characters with vertical lines like > "1", "I", "l", etc. to be faint or unreadable. > Long ago, DEC techs (and others,) would troubleshoot boards in the field, because boards cost so much. Now the boards are cheap, the techs cost a lot more, so board swap is financially better. Assuming from your return address that you have some access to a reasonably equipped service bench, the first thing I would do would be to run a capacitor analyzer on the large filter caps on the power supply. I would generally prefer to use a unit that can measure the cap's series resistance also, not just capacity. Note also that this can happen to caps from just sitting. It sounds like old wives' tales, but it makes sense to rejuvenate a power supply that has been sitting for a relative long time, (over a year or more), by putting it on a Variac and slowly raising the voltage. -- Frank R. Borger - Physicist ___ "Have the accordion player sound the Michael Reese - U of Chicago |___ charge!" - "He can't sir, he took a Center for Radiation Therapy | |_) _ bullet in the bellows during 'Lady of net: Frank@rover.uchicago.edu | \|_) Spain.'" - "Good!" Dave Barry ph: 312-791-8075 fa: 791-2517 |_) ////////////////////////////////////////////////////////////////////////////// X-Date: 27 February A.D. 1995 X-From: shuford@cs.utk.edu Here is a company that sells refurbished DEC, Televideo, and Wyse terminals and dot-matrix printers. Also, the company will repair most brands of terminals for a flat rate of $79.00 (US). Computer Hardware Resources, Inc. Houston, Texas WATS voice: 1-800/410-6161 POTS voice: +1 713/683-8977 /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ United Service Applications Inc., is a "Depot Level" computer-service company; monitors, PCs, and flat-panel displays (including LCDs) repaired. http://www.tdmdesign.com/usai/MONITOR.HTM United Service Applications, Inc. Suite O-8 17875 Skypark Circle North Irvine, California 92714 Voice: +1 714/757-3266 Fax: +1 714/757-3263 Email: ////////////////////////////////////////////////////////////////////////////// >Newsgroups: comp.terminals >Date: Sun, 19 Jul 1998 10:19:53 -0400 >From: Steven >Subject: device to repair terminals > >I try to repair computer terminals of the company I work in. >I know there is a device which I can hook up to the port in >the back which can recirculate the keyboard signals as input >signals to the terminals while I repair the communication >board problem. Anyone knows what this device is called >and where can I get it? What you want is a serial loopback connector. Try Black Box Corporation or Digikey. http://www.blackbox.com/ voice: +1 724/746-5500 fax: +1 724/746-0746 http://www.digikey.com/ voice: 1-800/344-4539 +1 218/681-6674 fax: +1 218/681-3380 ...RSS ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: utkcs2!transfer.stratus.com!news.bbnplanet.com!feed2.news.erols.com !erols!news.magicnet.net!nntp1.jpl.nasa.gov!netline-fddi.jpl.nasa.gov !helios!litwin Organization: Jet Propulsion Laboratory (NASA) Message-ID: <6p2acp$jt2@netline.jpl.nasa.gov> References: <35B20089.DC9B1FB7@ix.netcom.com> <35B37E5E.D1F01DD@rmi.net> Date: 21 Jul 1998 14:59:37 GMT From: Todd Litwin Subject: Re: device to repair terminals Original question: >> >> I try to repair computer terminals of the company I work in. >> I know there is a device which I can hook up to the port in >> the back which can recirculate the keyboard signals as input >> signals to the terminals while I repair the communication >> board problem. Anyone knows what this device is called >> and where can I get it? One response: > >It's called a "loopback plug". Usually a DB-9 or DB-25 connector with >pin 2 connected to pin 3. >What you should use is generically called a "break-out box". Usually has >LEDS, test points, etc so you can effectivly troubleshoot other >interface problems, etc. >Available from any good test equipment or cabling vendor. Actually, if you only want to loop back the output to the input, then you could do what I do. Take a paper clip; unfold it and bend it into a U; stick the 2 ends in sockets for pins 2 and 3 (assuming your terminals have female DB-25 connectors). I've done this for years, and it's worked just fine. And it's a lot cheaper and more convenient than buying fancy equipment. (Fancy equipment is also nice for many other situations; it's just not needed here.) -- Todd Litwin Jet Propulsion Laboratory (818) 354-5028 Todd.E.Litwin@jpl.nasa.gov ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Message-ID: References: <3A72561E.94A2B9E3@home.com> NNTP-Posting-Host: 24.13.83.35 Date: Sat, 27 Jan 2001 07:42:02 GMT From: "dls2" Subject: Re: Making a loopback plug "Calyth" wrote: > Since I was unable to locate a loopback plug, I'm going to > make one. This one is going to put on a Memorex 2192-c > with a 25pin serial port on the back. I've got word that I > could put the 2 and 3 pin together, but is there any other > pin that I have to solder together? Solder? What's wrong with using an ordinary paperclip? Unless you need to establish flow control, only pins 2 & 3 need to be connected, for a simple loopback connection. Do you think the fact that only a paperclip is required might explain why you were unable to find a loopback plug, despite the relative abundance of passthrough and null-modem serial cabling? -- Derrick Shearer ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: utkcs2!darwin.sura.net!mips!think.com!ames!agate!stanford.edu!rutgers !att!cbfsb!cbnewsb.cb.att.com!wa2ise From: wa2ise@cbnewsb.cb.att.com (robert.f.casey) Subject: Re: VT220 questions Message-ID: <1992May10.222121.20507@cbfsb.cb.att.com> Date: 10 May 92 22:21:21 GMT References: <1992May6.170201.12039@phillip.edu.au> Sender: news@cbfsb.cb.att.com Organization: AT&T Bell Labs Lines: 18 In article <1992May6.170201.12039@phillip.edu.au>, t9114145@phillip.edu.au writes: > >I've just acquired a VT220, made in 1985. 'setup' says V2.00. > >How do I connect a printer to it, i.e. what are the pinouts to make a >DEC-to-25 pin serial adaptor. Also does anyone have a standard set of >pinouts for a 25-pin serial printer's 25-pin D? I'd like to know this, too (can't RTFM 'cause I don't have a manual!) >The screen is very jittery right after it gets turned on, but smooths >out once it's warmer until you can't see the jitter any more. Anyone >have any suggestions what this might mean or how it could be fixed? The >20-odd VT220's at college don't do this. My VT220 had jitter. Found, in my case, it was a dirty horizontal hold trim pot. To get to it, you have to take the back off. It's on the left side if the flat circuit board, foward (if memory serves right). I replaced it in mine (a 5K trimpot, think I got the replacement from Radio Shark). ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: utkcs2!gatech!ncar!virga.rap.ucar.edu!ren Message-ID: <1992Jun5.142628.1101@ncar.ucar.edu> Keywords: Sources for replacement terminal parts Sender: news@ncar.ucar.edu (USENET Maintenance) Organization: Research Applications Program/NCAR, Boulder, CO Date: Fri, 5 Jun 1992 14:26:28 GMT From: ren@virga.rap.ucar.edu (Ren Tescher) Subject: SUMMARY: VT-320 flyback source needed I wrote: > >Yesterday my VT-320 smoked. Opening the case I found a cracked and >melted flyback transformer. I haven't checked to see if it took the >Horizontal Output Transistor (H.O.T.) with it. Nor have I called >DEC for a part number/price. No part # is on the flyback. I have >replaced flybacks many times before (let me tell you about my RCA >television repair days!). Has anyone replaced the flyback before, >and where did you get it? The Dalbani catalog did not have a DEC >category. From: Blair Groves | |Ren, you might try calling Sharon Industries in San Jose California, |they are at (408)-456-1600... they have a lot of parts for TeleVideo |terminals mainly, and all the other popular terminal brands. They are |pretty reasonable about prices. Terry Torres can look after you there. From: ssi!cjr@uunet.UU.NET (Cris J. Rhea) | Try Computer Component Source, Inc. (1-800-356-1227) A VT 320 FB is 17.99 qty 1. [note: They were the only ones whose catalog I've received so far, and they also have a Wyse-60 flyback kit for $11.99! ren] From: George Konstantinopoulos | Try CRC Components Inc. (800)822-1272 or (714)468-9711 DEC wants a $160 to replace the motherboard! (They won't sell the part). Thanks to those who replied! ren n0pvi dona nobis pacem ////////////////////////////////////////////////////////////////////////////// Newsgroups: misc.forsale.computers,misc.forsale,comp.terminals Path: utkcs2!darwin.sura.net!haven.umd.edu!uunet!sun-barr!decwrl!pa.dec.com!alf.dec.com!easy.enet.dec.com!mitcham Message-ID: <1992Nov9.115318.9160@netnews.alf.dec.com> Keywords: VT220 terminal Lines: 25 Sender: news@netnews.alf.dec.com (USENET News System) Reply-To: mitcham@easy.enet.dec.com () Organization: Digital Equipment Corporation References: Distribution: na Date: Mon, 9 Nov 1992 11:53:18 GMT From: Andrew Mitcham Subject: Re: VT220 Terminal Corrective action as suggested by the VT220 Pocket Service Guide: VT220 Keyboard Error - 4 1. Check to see if keyboard is plugged in (re-seat it, even if it is. -AM) 2. Replace the keyboard (if you have another terminal, try its keyboard -AM) 3. Replace terminal controller board 4. Replace power supply / monitor board Hopefully it is only a matter of the keyboard cable not seating properly. Otherwise, it looks as though repair may be in order. Good luck, -Andy -- +---------------------------------------------------------------------+ | Andrew Mitcham | The opinions expressed here | | Digital Equipment Corporation | are my own and not those of | | Customer Support Center | my employer unless otherwise | | Alpharetta, Georgia | stated. | | email: mitcham@rhett.enet.dec.com | | +---------------------------------------------------------------------+ ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!news.msfc.nasa.gov!bcm!cs.utexas.edu!news.sprintlink.net !beyond.escape.com!escape.com!rjw Date: Sun, 19 Mar 1995 20:57:11 -0500 Message-ID: From: Internet Consulting Subject: Monitor repair and sales... Micro Technology System 260 Main St Hackensack, NJ 07601 Ph: +1 201/343 6605 FaX: +1 201/343 6894 Micro Technology System specializes in all PC parts repairs, including Monitor repairs @85, k.brds@30,floppy drives @25,mac f.d@40,at/xt power supplies @30, system brd from $50, terminals $125. MTS can also supply all your system and peripheral needs at competitive prices. For example: 14" SVGA int $165, 14" SVGA n.i 0.28 $185; give us a call. MTS has in-house CNE to answer all your technical questions. Our technical support is free. MTS provides on-site or in-house repairs to all makes of computers. Lans and cabling jobs done at low rates. 20 mile pick-up & delivery service offered @6 for one piece and $10 for two or more pcs. pls call for schedule. for more info call mts +1 201/343 6605 fax +1 201/343 6894 Escape.com takes no part in this ad. Posting done by RJW Internet Consulting ////////////////////////////////////////////////////////////////////////////// [ARCHIVER'S NOTE: the Stratus V102 video terminal referred to below is an OEM version of the Televideo 955.] .............................................................................. Message-ID: <6DF363942AA8D311937A00105AABE7BBDBFDD7@syssvr3.descc.com> Organization: Double Eagle Steel Coatings Date: Mon, 1 Mar 2004 09:30:47 -0500 To: Info-Stratus*list.stratagy.com From: "Hogan, Phil" Subject: IS:: v102 repairs (terminals) Was wondering whether anyone repairs V102 terminals or knows who does? The company that was doing the repairs for us went out of business. Anybody using any off-the-shelf terminals instead of V102's?  How's the functionality and durability?  We use the V102's on the plant floor in a manufacturing environment and they hold up better than you'd expect.  We have more keyboard problems than CRT problems. TIA, Phil Hogan hogan@descc.com .............................................................................. Message-ID: Date: Mon, 1 Mar 2004 11:24:14 -0500 To: Info-Stratus*list.stratagy.com From: JOE_MATTIA*qvc.com Subject: Re: IS:: v102 repairs (terminals) We have been using Black River Computer: Gary M Reimer Technical Administrator Black River Computer, Inc. 7630 Race Rd. North Ridgeville, OH 44039 Voice: 216/327-7999 Email: gmr@apk.net Web: http://www.blackriver.com/ ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.unix.admin,comp.terminals Path: utkcs2!darwin.sura.net!spool.mu.edu!news.nd.edu!mentor.cc.purdue.edu!noose.ecn.purdue.edu!dynamo.ecn.purdue.edu!wb9omc From: wb9omc@dynamo.ecn.purdue.edu (Duane P Mantick) Subject: Re: Leaving terminals on Message-ID: Keywords: terminals Sender: news@noose.ecn.purdue.edu (USENET news) Organization: Purdue University Engineering Computer Network References: <1992Oct13.224537.4643@datamark.co.nz> <1bjbsqINNcii@swan.doc.ic.ac.uk> Date: 15 Oct 92 17:06:18 GMT Fanning the flames..... :-) I think it depends on the situation. If you have your OWN terminal and you don't share it with other people, AND you don't use it more than 8 hours out of a 24 hour day, turn it off. Caveat: don't turn it on and off and on and off and on and off every few minutes. You'll more than likely blow the hell out of it. If you have a terminal in an office, for example, leave it on ALL day and turn it off at night. In our public terminal rooms, I incourage people to leave the terminals ON. The room is open 24 hours and people USE them 24 hours. The constant power-cycling is proven to be detrimental. More Caveat: terminals with switching power supplies are more sensitive to power-cycle transients than terminals with a linear, brute-force power supply, in general. Paul Zawada mentioned the WYSE terminals - they are an abortion whether power-cycled or not. Our WYSE 50's blow up for no reason other than incredibly stupid design features--like electrolytic capacitors located 1/16 inch from a HOT heat sink. Heat dries out cap, cap fails, terminal goes boom. Most common in the WYSE50 is C206 on the MPS board. The best cap we've found as a replacement is the Nichicon HA series. These dudes are DESIGNED for the high current and high heat of a horizontal deflection circuit. (Wyse should have used them in the first place....) You can't really make a blanket statement about power-cycling that applies in ALL cases. The best way I could phrase it is: Don't turn it off if you're coming back in less than an hour. DO turn it off if you're NOT coming back for MORE than an hour. If it's a WYSE, throw it in the trash.... :-) Duane Mantick Engineering Computer Network, Purdue University Supervisor of Terminal Repair The above comments only represent my opinion. Period. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!darwin.sura.net!howland.reston.ans.net!cs.utexas.edu!swrinde !ihnp4.ucsd.edu!ames!erg.sri.com!noose.ecn.purdue.edu !constellation.ecn.purdue.edu!wb9omc Message-ID: References: Date: Fri, 15 Apr 1994 22:27:01 GMT From: wb9omc@constellation.ecn.purdue.edu (Duane P Mantick) Subject: Re: Wyse 60 repair help wanted bill@NETSYS.COM (William Petrisko) writes: > >Our maintenance contract on our Wyse 60 terminals has finally >come to an end, so we are being forced to repair any units that >die in-house (until we can afford replacement units next year.) My condolences. > Has anyone come up with a cheat sheet/quick-tips sheet for > repairing common Wyse 60 problems? Here is the breakdown > of problems... if anyone has any suggestions, I would > appreciate the assistance! At my site we have mostly Wyse50's..... >1) K-in-the-corner problem upon powerup. Occasionally this > can be cleared by holding down the "G" key while powering > up... but it eventually returns and stays. The service > manual says that is a "non-volatile RAM error." What does > this mean? Would replacing U2 (nonvolative memory) fix > this problem? Or is the problem deeper than that? Depends. The problem could be the NVR itself or something that is a latch or addresses the chip. You might have to replace two or three chips to find the REAL problem. >2) Popped and smoked. Is there a common capacitor that blows > up, other part that blows up, or would this be a flyback > transformer problem? There is a WYSE 60 flyback kit that consists of: a) a new flyback, PN 420016-01B (unless changed since) b) a new diode for position D203. Remove the General Instruments RGP5100 and install the UF4007 in the kit. c) a new transistor for position Q202. Remove the BU406 and replace with the 2SC2898 in the kit. the kit part number (last I knew) was 920064-01. I don't know a current price on it. This worked well on what 60's we had. I think every single one failed on this flyback bit....and most of the time the flyback will show a nice big bulge on its sides, or at the very least some nasty looking bubbling in the plastic. (typically) That isn't to say that something else couldn't smoke. If the 60 is anything like the 50, it too is a self-nuking device. :-) The 50 has a capacitor, C206, in the horizontal deflection circuit. C206 seems to be the crux of many MPS board problems in the 50. We replace them here with a Nichicon HA series cap, 4.7 uF at 50 volts. We get these from Jacque Ebert Associates up in New York. The HA series cap has a VERY high AC ripple current rating, and that seems to be the culprit (or at the very least, related to the culprit) - as in nearly 3 YEARS of using that capacitor, we have not had a SINGLE wyse50 come back with a C206 related problem. At least, not one that wasn't already there..... :-) And if you think the HA series is too expensive of a capacitor, I wish you luck finding another bi-polar cap that has that high of an AC ripple current rating. Most of what I've located isn't even close. Further hints: I strongly suggest that if the terminal is over 3 years old and you fix the main problem, go through and replace most, if not all, of the electrolytic capacitors in the video and power supply circuits. Pay particular attention to those near heat sinks or near hot semiconductors. I don't know if the 60 runs as hot as the 50's do, but whoever designed the Monitor/Power Supply board for the 50 ought to be SHOT for having put electrolytic capacitors within 1/8 or 1/16 of an inch of a skin-burning hot heat sink. REAL dumb idea. >3) Video problems. Usually lines appearing verically through > the display, either after warming up or after smacking the > terminal on its side. It would appear this is a heat-related > and/or shock-sensitive (bad connection?) type of problem. > Again, are the common parts that fail that I could check for? Never seen this one..... Duane Mantick .............................................................................. Jacque Ebert Associates, Inc. 120 Pratt Oval Glen Cove, NY 11542-1482 +1 516/671-6123 .............................................................................. Component sources: http://www.galco.com/kwpages/JACQ/CAPA-0001.htm Galco Industrial Electronics 26010 Pinehurst Dr. Madison Heights, MI 48071 USA sales: 1-800/575-5562 office: 1-800/521-1615 office: +1 248/542-9090 office: +1 248/544-7155 http://www.fouraker.com/JACQUESEBERT.html 1-800/635-0420 L&M Wholesale Electronics 1700 W Waco Dr. Waco, TX 76701 USA +1 817/754-4644 .............................................................................. Web site specializing in information on capacitors: http://www.faradnet.com/ ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!gatech!howland.reston.ans.net!news.cac.psu.edu!usenet From: BJJ@ECL.PSU.EDU (Bryan J Jensen) Subject: Re: VT101 video woes... Date: 23 Jul 1993 05:00:39 GMT Organization: Penn State Engineering Computer Lab Lines: 15 Message-ID: <22nr9n$orj@genesis.ait.psu.edu> References: NNTP-Posting-Host: ecl.psu.edu In-Reply-To: adam@owlnet.rice.edu's message of Sat, 17 Jul 1993 04:33:15 GMT In adam@owlnet.rice.edu writes: > I have a lovely old VT101 sitting here that I inherited. > ... I get nada on the video. The video board is the one to the side of the CRT with all the pots. On the video board, The 75uF, 6V capacitor C439 and its neighbor, diode CR408, have a real bad habit of burning up. The Flyback transformer or Horizontal Output Transistor sometimes go bad too, of course, as they seem to in any monitor. I forget where the transistor is. I'd mail this to you, but I've never gotten mail to work from VMS NEWS. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <880111a3.0208281603.20d1133e@posting.google.com> Message-ID: Organization: Cox Communications Date: Thu, 29 Aug 2002 04:14:35 GMT From: mroberds@worldnet.att.net Subject: Re: Wyse 60 Problem On 2002-08-28, Drew Taylor wrote: | | I have a Wyse 60 connected to a linux machine. It worked great for | months with no problems but all of a sudden one day it stopped | connecting to the host. | | I checked out the serial line back to the machine with another wy60 | terminal and it worked fine. I also matched the setup of the broken | wy60 with the setup of the working wy60 to make sure all was in order, | still no soap. | | It turns on fine, video initializes, keyboard initializes and its able | to enter setup, but it will not communicate to the host (either via | the aux or the modem port). Since I have eliminated the physical | serial line and the terminal setup, I'm guessing it's another problem | with the terminal. Something on the modem port has died. This is pretty common, because the serial lines are usually long and can pick up lots of noise, voltage spikes, etc, that get fed back into the port. The RS-232 ports require positive and negative voltages to operate. It's possible that you have lost the negative output of the power supply, which means that about half the bits won't make it out onto the serial line. It's remotely possible that you've lost the positive output of the power supply, but since that one usually powers other stuff in the terminal, more of the terminal usually dies when it goes out. Probably the most common things to go out are the "line driver" and "line reciever" chips. These translate the 0V/+5V logic in the terminal to the +12V/-12V logic on the serial line (driver) and vice versa (reciever). They usually bear the brunt of spikes coming in on the serial port. The standard chips for this for a long time were the 1488 and 1489 chips, but there are others. In many terminals, the line drivers and receivers are in sockets for easier replacement. Since you have a working terminal of the same model, you can probably troubleshoot it by comparing the two. The simplest thing is to power up both terminals without connecting them to the host, and use a voltmeter to compare the voltages on all pins of the serial port with respect to chassis ground, the metal shell of the serial port connector. This will probably verify that the broken terminal's port is not putting out the right voltages. To go farther you'll have to open up the terminal. This isn't too bad as long as you stay away from the fat wire to the CRT (10 kV - 25 kV), the board at the neck of the CRT (200 V), and the power cord connections (120 V). You might luck out and find something that's visibly blown up next to the modem port, in which case replacing it will probably fix the problem. If not, start comparing voltages with respect to chassis ground on the same pins in the broken and working terminals. This should tell you pretty quick if one of the power supply output voltages has died. If the terminal uses the 1488/1489 line driver chips, or other socketed line drivers, you may be able to swap parts between the two terminals to get the broken one working. If you're not too familiar with component-level repair, it might help to take a look at http://www.repairfaq.org/ and ask questions in the newsgroup sci.electronics.repair. Good luck! Matt Roberds ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <880111a3.0208281603.20d1133e@posting.google.com> Message-ID: <880111a3.0208291521.241e8e6c@posting.google.com> Date: 29 Aug 2002 16:21:07 -0700 From: Drew Taylor Subject: Re: Wyse 60 Problem I compared the RS-232 port voltages on the working and the bad terminal and found that all of the voltages were the same, except for pin 2 (the TXD pin if I remember correctly). The working terminal returned 12v while the busted one read 10.8v. Other than that, they both returned 13v on the RTS pins, and 11v on the DTR pins. Also I opened it up to look for the driver/receiver ICs and found 2 ICs marked MC1489AP and 2 marked MC1488P. Both were unsocketed :( From this information would it be worth the risk to hunt down and install new line driver and receiver ICs? I think it would be very likely that a voltage spike from some source could have knocked it out since the serial line runs through a populated telco closet. Thanks for your help. -Drew ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <880111a3.0208281603.20d1133e@posting.google.com> <880111a3.0208291521.241e8e6c@posting.google.com> Message-ID: Organization: Cox Communications Date: Fri, 30 Aug 2002 05:40:35 GMT From: mroberds@worldnet.att.net Subject: Re: Wyse 60 Problem Drew Taylor wrote: > >I compared the RS-232 port voltages on the working and the bad >terminal and found that all of the voltages were the same, except for >pin 2 (the TXD pin if I remember correctly). The working terminal >returned 12v while the busted one read 10.8v. Other than that, they >both returned 13v on the RTS pins, and 11v on the DTR pins. Well, there is something different about the broken terminal. If you want a little more assurance, and if you can measure the voltages while the port is hooked up, that might provide a little more info. First, measure and note the voltages on the end of the cable coming from the host, while the cable is unplugged. Then plug the cable into each terminal and check the voltages again. What you're looking for is voltages that go down a lot (like from 12v to less than 3v) when the cable is plugged in, which indicate a shorted or damaged driver on that pin. >Also I opened it up to look for the driver/receiver ICs and found 2 >ICs marked MC1489AP and 2 marked MC1488P. Both were unsocketed :( You probably have a 1488/1489 pair for each port. Being unsocketed is not too big of a problem, but you will have to unsolder the old ICs. I would suggest installing sockets so when this happens again your life will be simpler. If you can tell which ICs go with which port (modem/aux) you can just replace the two on the modem port, but if not you'll need to change all 4. The chips are less than $2 each so this isn't a big deal. >From this information would it be worth the risk to hunt down and >install new line driver and receiver ICs? Well, you do have a spare terminal so you're not dead in the water. And the broken terminal doesn't work now, so you probably can't make it worse by carefully working on it. It is possible that the damage didn't stop at the line driver and receiver chips, but quite often it does. "Hunting down" should be fairly easy. The 1488 and 1489 are among the few chips that Radio Shack still stocks, if you are in the US. In their 2001 catalog both chips sold for $1.29 each. The sockets for them are 2 for $1. >Thanks for your help. You're welcome! Matt Roberds ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <880111a3.0208281603.20d1133e@posting.google.com> <880111a3.0208291521.241e8e6c@posting.google.com> <880111a3.0208301119.3ac6448@posting.google.com> Message-ID: <880111a3.0209070604.200121c9@posting.google.com> Organization: http://groups.google.com/ Date: 7 Sep 2002 07:04:28 -0700 From: Drew Taylor Subject: Re: Wyse 60 Problem rewt@loritsu.com (Drew Taylor) wrote in message news:<880111a3.0208301119.3ac6448@posting.google.com>... > That looks like the problem. The voltage on at least the TXD pin drops > about 5 volts when the serial line is connected to the busted > terminal. On the TXD pin there is about an 8v difference between the > busted and the working terminal. > > RadioShack has dropped most of its ICs and it looks like all the line > drivers were included in the drop, the 2001 commercial catalog that I > have is pretty much worthless now (looks like they have finally > eradicated Tech America's product line). DigiKey has a large stock of > line driver ICs so I plan on using them. > > Thanks! > > -Drew Taylor > http://WWW.ElectronicsChat.Org/ I replaced all 4 driver and receiver ICs, and that fixed the problem. I also socketed them, the way it should have been done in the first place. Thanks for the help. -Drew ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <880111a3.0208281603.20d1133e@posting.google.com> <880111a3.0208291521.241e8e6c@posting.google.com> <880111a3.0208301119.3ac6448@posting.google.com> <880111a3.0209070604.200121c9@posting.google.com> Message-ID: Organization: Cox Communications Date: Sat, 07 Sep 2002 17:31:32 GMT From: mroberds@worldnet.att.net Subject: Re: Wyse 60 Problem Drew Taylor wrote: > > I replaced all 4 driver and receiver ICs, and that fixed the problem. Cool! Thanks for posting back with the solution. Glad I could be of assistance. > I also socketed them, the way it should have been done in the first > place. Did you buy 4 extra ICs, which are now in their storage tube taped to the back of the terminal? :) Matt Roberds ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.sys.dec Path: cs.utk.edu!darwin.sura.net!math.ohio-state.edu!howland.reston.ans.net !agate!doc.ic.ac.uk!warwick!bsmail!siva.bris.ac.uk!ard Message-ID: <15AUG199318211980@siva.bris.ac.uk> Sender: usenet@bristol.ac.uk (Usenet news owner) Nntp-Posting-Host: siva.bris.ac.uk Organization: University of Bristol Physics Department References: Summary: I need to open a 220 case but can't Keywords: vt220 dec terminal Date: Sun, 15 Aug 1993 17:21:00 GMT From: ard@siva.bris.ac.uk (PDP11 Hacker .....) Subject: Re: how to open vt220 case In article , jrl2@crux1.cit.cornell.edu (Jeffrey R. Luszcz) writes... > >Hello, > > I have a couple of vt220s which are no longer functioning, > one a couple of them, the only problem is with their power > switch, others are jsut dead. I would like to take the good power > switches out of the DEAD ones and put them in the less dead ones. > > The problem is that I can't get the VT220s cases open, even though > I've taken out all the screws I could find, even the two under the > white rubber hider things. Do I have to take off the stand? If so > how? Thanks, I've just fixed a load of VT220's here in Bristol. Here's how I got the case open: 1) Remove all cables (comms, mains, keyboard, etc) from the back. 2) Place the terminal face down 3) Remove the 3 white plastic caps (1 from rear, 2 from base) with a small screwdriver 4) Remove the 3 screws exposed in step 3 5) Pull the case off upwards. The most common fault seems to be no horizontal hold caused by a o/c preset. Just twiddle the preset marked HH on the PSU/monitor PCB (flat at the bottom), and return it to its original position. That's fixed about 10 so far. If you know what you are doing, do this with the power on, and check the the picture locks, and then turn it off and on again, and see that the picture comes into lock again. But be careful - there are high voltages in the VT220 case, and I wouldn't like anyone to get injured. Other common faults are ROMs with stuck data pins (swap from other dead terminals), and buffer failure on both the keyboard and serial ports. They're the 8-pin ICs near the back of the logic board, and are easy to replace if you don't mind soldering in ICs Unlike the VT3xx series, I've never had a PSU or line output failure on the VT220 family. -tony ////////////////////////////////////////////////////////////////////////////// Path: cs.utk.edu!gatech!newsjunkie.ans.net!newstf01.news.aol.com!newsbf02.news.aol.com!not-for-mail Newsgroups: comp.terminals Organization: America Online, Inc. (1-800-827-6364) Lines: 15 Sender: root@newsbf02.news.aol.com Message-ID: <3l6n83$grl@newsbf02.news.aol.com> References: <3l5an8$8fc@paperboy.ids.net> Reply-To: psichel@aol.com (PSichel) NNTP-Posting-Host: newsbf02.mail.aol.com Date: 27 Mar 1995 10:56:51 -0500 From: psichel@aol.com (PSichel) Subject: Re: VT240 NVR Error In Message-ID: <3l5an8$8fc@paperboy.ids.net> you wrote > I have a VT240 with an LK201 keyboard and VR201 monitor. > > At startup it displays the following: > > VT240 NVR Error - 10 You're right, this is the Non-Volatile RAM. These chips can go bad after a while (rated for 10,000 write cycles). NVR Error means the terminal detected a checksum error reading from the NVR. Sometimes you can fix this by Restoring Factory Defaults and then Saving Settings. If that doesn't work, you probably need a new NVR chip. - Peter ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair,comp.sys.dec.micro,comp.terminals Path: cs.utk.edu!gatech!nntp.msstate.edu!emory!swrinde!howland.reston.ans.net !spool.mu.edu!bloom-beacon.mit.edu!ai-lab!bronze.lcs.mit.edu!not-for-mail Message-ID: <36hrca$o4u@bronze.lcs.mit.edu> Organization: Guest of MIT AI and LCS labs X-NNTP-Posting-Host: bronze.ai.mit.edu Date: 30 Sep 1994 16:10:50 -0400 From: moisan@bronze.lcs.mit.edu (David Moisan) Subject: FOLLOWUP: (Belated) DEC VT240/VR201 problems Summary: Terminal *and* CRT were fine! I posted a month or so ago about a DEC VT240 terminal and a VR201C amber monitor, both apparently not working. The VT240 I posted about turned out not to have a problem; I'd forgotten that it used the LK201 keyboard for its bell. Plugged in my DM KB and monitor, voila! Normal setup screen! On the VR201, as suggested by Tony, I checked the HV and the CRT pin voltages. Nada. The only thing getting lit was the CRT heater. In a million years, I never thought the HV would be screwed, but there it was (or there it wasn't!) I swapped boards with my old DECmate monitor with the dim CRT. Works perfectly. The VT240 is going to my friend, but it looks like he'll have to find a new monitor and KB...:/ Thanks much to Tony and Co. for their suggestions! Dave -- | David Moisan, N1KGH /^\_/^\ moisan@bronze.lcs.mit.edu | | 86 Essex St. Apt #204 ( o ^ o ) n1kgh@amsat.org | | Salem. MA 01970-5225 | | ce393@cleveland.freenet.edu | | | ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!gatech!newsjunkie.ans.net!newstf01.news.aol.com !newsbf02.news.aol.com!not-for-mail Date: 27 Mar 1995 10:38:29 -0500 Message-ID: <3l6m5l$gkb@newsbf02.news.aol.com> References: From: psichel@aol.com (PSichel) Subject: Re: VT-330 Error 4 In message you wrote > > When I start up my (hamfest special!) new VT330, it complains > about keyboard error 4, but it keeps on going. > >This is with LK201 keyboards that test out fine on my Rainbow. > >Does the 300's expect a non-LK201 keyboard? No, the LK201 is fine for the VT330. Keyboard error 4 means the terminal failed to receive the selftest OK result code from the keyboard. Maybe a key was down, or there's a poor electrical connection to the terminal (check for dirty or bent pins on the VT330 keyboard connector). - Peter ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair,comp.terminals Path: utkcs2!transfer.stratus.com!cam-news-feed2.bbnplanet.com !cam-news-hub1.bbnplanet.com!news.bbnplanet.com!nntprelay.mathworks.com !newsfeed.internetmci.com!164.67.42.145!awabi.library.ucla.edu !137.82.194.1!unixg.ubc.ca!alph02.triumf.ca!shoppa Message-ID: <6csf78$o61$1@nntp.ucs.ubc.ca> References: <5u7rc6.912.ln@tweety.athome.de> NNTP-Posting-Host: alph02.triumf.ca Organization: TRIUMF, Canada's National Meson Facility Date: 23 Feb 1998 18:30:00 GMT From: shoppa@alph02.triumf.ca (Tim Shoppa) Subject: Re: VT220 problem In article <5u7rc6.912.ln@tweety.athome.de>, Olav Woelfelschneider wrote: > >John Rollins wrote in comp.terminals: >JR> >JR> 1- I get a keyboard error 4. What does this mean? I already tried another >JR> cable(from my telephone handset, I hope the wires aren't reversed like on >JR> a Mac Plus...) and it still gives me the error. > > Be careful, such a cable might overheat. It is said there have been fires > because of prolonged use of a handset cable... > >The keyboard does not have very much components. It's either its cpu, then >you're hosed, or its driver. In the latter case, you might get a replacement >part somewhere. Not necessarily from radio shack, though... (: > >JR> >JR>The VT220 I have uses a socketed 8051. Pretty east to find and replace, if >JR>that's what's wrong. Desoldering isn't that hard. but I hate those little >JR>Radio Shack bulbs. I need to go get some of those desoldering wicks... >JR>OK, two more questions. How do I get into the keyboard? I see those two >JR>nuts on the bottom, but there must be more than that holding it together. >JR>Keyboards are usually rather interesting to take apart. And what is that >JR>big connector on the back marked "20mA"? I would guess it's some sort of >JR>power connector for something, but I can't figure out what. >JR> >JR>-JR http://members.tripod.com/~jrollins/index.html - Computers Actually, there are two other common causes (which you probably ignored because they were "obvious"): 1. The modular jack on either end has failed or has separated from the PC board mount. 2. The voltage regulator in the keyboard has failed. In the stock LK201 keyboard, the voltage regulator is just a 7805. Some probing with a voltmeter will quickly tell you if the 7805 is getting power (if not, check the jacks) or not putting out power (in which case, replace the 7805.) LK201's aren't exactly rare keyboards - any DEC reseller has them stacked up by the hundreds. Tim. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.sys.dec Path: cs.utk.edu!nntp.memphis.edu!nntp.msstate.edu!emory!swrinde!cs.utexas.edu !news.sprintlink.net!demon!news.demon.co.uk!not-for-mail Message-ID: <3rvoeo$s14@imp.demon.co.uk> Sender: news@news.demon.co.uk References: <28MAY199510213610@vx.cis.umn.edu> <1995Jun2.163308@cchs.su.edu.au> Date: 18 Jun 1995 00:28:24 +0100 From: mike@mmiller.demon.co.uk (Mike Miller) Subject: Re: Terminals going up in smoke? enigma@netcom17.netcom.com (Holly L. McGrath) wrote: > >Posting for my boyfriend, who knows a lot more about them than I do: >he says that the flyback transformers start leaking high voltage well >before they actually start failing, and you can spot this if you take >the terminal into a dark room and look down into the vents. The tube >will glow, but if you see arcing on the high voltage transformer, get >Corona Dope or if you can't get that get high voltage GLPT and >liberally coat the transformer. All of the used VT320's (except one) >that he has purchased have required this treatment, and are still >working. Sorry, but that's not what's wrong with them; it's the connection from the CRT to the motherboard. It's a known problem ...crap connectors. DEC won't recall them, and they burn out.....the brightness is also a known problem .....open the terminal up and adjust the brighness pot. I know because I used to work for DEC as a real engineer not just a contractor or a x-sme :) Mike Miller. " The Quicker This World Stop's Spinning The Quicker I Can Get Off " ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.sys.dec Path: cs.utk.edu!cssun.mathcs.emory.edu!emory!gatech!howland.reston.ans.net !cam.news.pipex.net!pipex!edi.news.pipex.net!pipex!sunsite.doc.ic.ac.uk !lyra.csx.cam.ac.uk!ard12 From: ard12@eng.cam.ac.uk (A.R. Duell) Subject: Re: Terminals going up in smoke? Date: 19 Jun 1995 12:33:37 GMT Organization: University of Cambridge, England Lines: 30 Message-ID: <3s3qr1$ans@lyra.csx.cam.ac.uk> References: <28MAY199510213610@vx.cis.umn.edu> <1995Jun2.163308@cchs.su.edu.au> <3rvoeo$s14@imp.demon.co.uk> NNTP-Posting-Host: club.eng.cam.ac.uk mike@mmiller.demon.co.uk (Mike Miller) writes: >enigma@netcom17.netcom.com (Holly L. McGrath) wrote: >>liberally coat the transformer. All of the used VT320's (except one) >>that he has purchased have required this treatment, and are still >>working. > Sorry, but that's not what's wrong with them... Well, I've certainly had flybacks (line output transformers) fail in VT320's and VT330's. They've actually cracked open, and emitted magic smoke. And, they test as shorted on my transformer tester. Getting new ones has proved to be rather difficult, though :-(. I don't recall any connector between the CRT and the logic board, other than the tube base and EHT flower, of course. The tube base (which looks to be of reasonable quality) is soldered to a small PCB, and I thought the wires linking this to the logic board were soldered at both ends. Maybe I've just misremembered it, though. > > Mike Miller. " The Quicker This World Stop's Spinning > The Quicker I Can Get Off " -tony ////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////// Newsgroups: alt.folklore.computers Path: cs.utk.edu!news.msfc.nasa.gov!europa.eng.gtefsd.com !howland.reston.ans.net!pipex!lyra.csx.cam.ac.uk!warwick!bsmail !siva.bris.ac.uk!ard From: ard@siva.bris.ac.uk (PDP11 Hacker .....) Subject: Re: VT10x Message-ID: <5OCT199418413844@siva.bris.ac.uk> News-Software: VAX/VMS VNEWS 1.41 Sender: usenet@info.bris.ac.uk (Usenet news owner) Nntp-Posting-Host: siva.bris.ac.uk Organization: University of Bristol Physics Department References: <1994Oct4.044842.28424@picarefy.picarefy.com> Date: Wed, 5 Oct 1994 17:41:00 GMT Lines: 53 In article , hshubs@BIX.com (Howard Shubs) writes... >jwbirdsa@picarefy.picarefy.com (James W. Birdsall) writes: > >> What's the difference between the VT100, VT101, VT102, and VT103? I just >>got several of the last two. The most obvious difference between the 102 >>and the 103 is that the 103 lacks a printer port and has a video in >>connector, but I'm interested to know whether there are any other, less >>visible differences. >I'm not sure what the VT103 was. I _think_ the VT103 was a VT100 with 4-slot Q-bus backplane in it. The standard CPU was the LSI11/2 (PDP11/03 CPU), but I am told an 11/73, or even a microvax2 CPU can be got in there. It's a rather nice object. > > >> Also, one of the 102's is frustratingly close to working. It passes all >>self-tests, local echo works fine -- it does everything except actually >>send data (don't know whether it receives or not). I have a little inline >>RS232 breakout box connected, and any time I hit a key, there seems to be >>exactly one level transition on the transmit line, then it gets stuck there. >>I've been through setup a bunch of times; baud, data and stop bits, parity, >>and everything else are fine as far as I can tell (some of the setup options >>are pretty obscure). If anybody recognizes this failure mode, I'd like to >>hear about it. Maybe a defective clock to the UART chip - but I'll have to check the printset (schematics) to be sure. They're pretty simple anyway. > >Standard procedure to fix these terminals was to take two broken ones and >make one working one by swapping boards until one terminal worked and one >terminal had multiple woes. I hope you didn't pay a lot for these things Maybe, if you are from "failed circus" :-). The real way to fix these involves checking the PSU (linear in the VT101, a nice, easy to repair, switcher in the VT100). Then, either fixing the video board (problems on this are simple - the main failures are the flyback transformer, shorted rectifiers which then kill the flyback transformer, or blown video output transistors), or fixing the logic board. Logic board faults are rare, so I've not had any of those to fix Oh, and please don't swap out video boards. The flyback transformer is _not_ part of the board, so that if a rectifier on the video board is dying, it will kill the good flyback you've connected it to. I've had to clear up a mess that started that way. -tony Bristol University takes no responsibility for the views expressed in this posting. They are the personal views of the user concerned. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!mp.cs.niu.edu !vixen.cso.uiuc.edu!howland.reston.ans.net!gatech!purdue !mozo.cc.purdue.edu!constellation.ecn.purdue.edu!wb9omc From: wb9omc@constellation.ecn.purdue.edu (Duane P Mantick) Subject: Re: Wyse break Date: 14 Jul 1995 18:27:31 GMT Organization: Purdue University Lines: 136 Message-ID: <3u6cuj$k2m@mozo.cc.purdue.edu> References: <3tv6p0$3js@news.nde.state.ne.us> sir@firstsol.com (Stu Rutkin) writes: > > In article <3tv6p0$3js@news.nde.state.ne.us>, > chammack@genie.esu10.k12.ne.us (Chris Hammack) wrote: > > > > Argh! I don't turn on the wyse for 3 weeks, and now...no picture! When > > or back of the cover (Wyse 60's and newer Wyse 50's). Sounds like the > monitor/power supply (MPS) board has croaked. There are plenty of repair > services around Alternatively, if the user is electronically experienced or knows someone who *is* (and for God's sake, if you don't know what you're doing, stay the hell out), you can open up the terminal and check C206 on the MPS board. C206 is on the right side of the board (when viewed from the back) and just forward from the flyback. This applies to wyse *50's*. On the 60's, there is a flyback replacement kit that includes the flyback and a transistor and diode, all of which beefs up the circuit considerably. Back to the wyse50. C206 needs to be a bi-polar electrolytic cap, 4.7 uF at 50 volts. HINT: do NOT use the cheapest one you can find! Cheap ones don't have a very good AC ripple current rating. I suggest the Nichicon HA series; we have had quite good luck with them here. Said ripple current rating on the HA's is given in AMPS, not milliamps like the cheap ones. In the wyse50, if it is the FIRST time that the terminal has failed since new, more than likely be C206 if the symptom is ONLY a loss of video and everything else seems to work. Each time C206 fails, the chance of other things failing goes UP. Several service vendors, and possibly wyse themselves, suggested replacing the 5-pin regulator at U101 (type L200C) when C206 croaks, although we have not found this to matter much. NOTE: if you think you smell ozone, take the back of the upper case OFF, and power up the terminal. Turn OFF the lights in the room and look at the flyback. If you see ANY pulpleish colored arcing on the top or sides of the flyback, REPLACE it. That arcing is nearly always the source of your ozone smell. The arcing will usually appear as very deep purple lines..... Further suggestion: BEFORE you attempt ANY kind of repairs, turn the power OFF and DISCONNECT the power cord from the terminal. THEN, and ONLY THEN, take a BIG screwdriver and discharge the CRT anode to the frame to get rid of most of the dangerous voltage. In the wyse, that anode runs at 14 Kv, and the CRT can hold a considerable residual charge even AFTER the unit is powered off, and can shock the snot out of you. Therefore, when you discharge, make sure that you don't come in contact with ANY of the metal parts in question. When you pull the MPS board out, take a REAL good look at ALL the electrolytic capacitors on that board. If ANY of them appear bulged or misshapen in ANY way, or badly discolored, REPLACE them. I suggest using replacements that have a 105 deg. C temperature rating instead of the usual 85 deg. C rating. The top (monitor/power supply) section of a wyse50 runs REAL hot. If you don't believe that, look at one that is 7 years old or so, and look for two nice brown spots on the top of the case that are directly above internal heat zones. The plastic of the case actually discolors from the heat! Electrolytic caps don't tolerate being soaked in heat all that well, and doing so shortens their life. Going to a higher rated cap. (temperature wise) will help this somewhat.... You have some moron of a designer at wyse or associated company to thank for many of these problems. No designer with an ounce of brains physically locates an electrolytic capacitor 1/16 of an inch away from a HOT heat sink UNLESS he WANTS the unit to fail as a deliberate design feature. I am experimenting with a real neat insulating material to protect the capacitors from the heat....just a little square of it to block the direct heat radiation from the caps, NOT enough to prevent the heat sink from dissipating the heat in the attached semiconductor. BUT, from our experience here there comes a time when the MPS board is just plain SHOT. You can still get NEW ones, which run about $110 or $120. Quite frankly, that isn't a lot less than a new terminal....and there are a shitpot of good used terminals out there for LESS. You can get SOME MPS boards repaired, but you don't usually get much of a warranty on them (at least not from what I've seen). My advice on a good used dumb terminal? Find a good used ADDS Regent 20 or Lear-Siegler ADM-5 in good condition. Things to look for: The Regent 20 should have a Keytronic keyboard, preferably a late revision; try to get a re20 with a serial number under 206000 - usually those lower will have the Panasonic K224 monitor in them, generally pretty reliable, ESPECIALLY the K224E4B later variant. Those after 206000 usually have an ADDS-built monitor that sucks. On the ADM-5's, check out the monitor - if it has the Zenith-built one with the off-board flyback, avoid it like the plague. If it has the Samsung monitor you will do much better. One common failure in the Samsung ADM-5 monitor: C413 on the video board. Just like the one on the Wyse board, this is a Horizontal Deflection cap and needs to be a bi-polar electroltyic. We are also using the Nichicon HA here with good success. The original was a 16 uF cap, but the HA series ends at 10 uF. This works just fine, BTW, and is also a 50 volt cap. Typical symptom of a C413 failure will be either no video, or a dashed vertical line up the center of the screen. Only a couple things to watch out for in the re20's Panasonic monitors: crappy solder joints on the flyback. Symptom is the screen flashes when you bump the terminal. Just resolder the flyback and you're in business. On the early K224 monitors, C431 and 432 will fail sometimes....you can replace them with about any equivalent standard electrolytic and they will be good for years. On the newer K224E4B, it is someting like C463 and 465. Same story. Symptom is a partial raster on the screen and/or a bright dot in the middle of the screen when you turn the terminal off. In each unit, one of those caps just sits and holds a charge until you turn the terminal off....then it discharges into one of the screen grids to shut off the electron beam to prevent that bright white spot, which will eventually etch a nasty dark splotch into the screen. Both the Regent 20 and the ADM-5 are jurassic technology, BUT - they are probably two of the most robust and well-constructed general- purpose dumb terminals ever built. Neither of them has very many "proprietary" parts in them, and while Panasonic has discontinued parts support for the Regent monitor, the ADM-5 monitor's Samsung flybacks can still be gotten from a few sources. They aren't 100% identical, but do work. Duane Mantick Supervisor of Terminal Repair Engineering Computer Network, Purdue University Disclaimer: comments made above do not represent any official viewpoint or endorsement from Purdue University. Neither them or I are responsible for what happens if an untrained idiot sticks his fingers where they don't belong...... ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!gatech!stallion.jsums.edu!news.uoregon.edu!vixen.cso.uiuc.edu !howland.reston.ans.net!agate!library.ucla.edu!info.ucla.edu!csulb.edu !csus.edu!netcom.com!NewsWatcher!user From: voicebox@netcom.com (Dave C.) Subject: Re: Need some tips on repairing Wyse monitors Message-ID: Sender: voicebox@netcom14.netcom.com References: <3u642l$pud@sauron.multiverse.com> Date: Sat, 22 Jul 1995 17:50:35 GMT Lines: 26 a03047@giant.rsoft.bc.ca (Russell Owsianski) wrote: > Also, many of our Wyse 50s make a terrible 'screaming' noise. I'm guessing > thatthis might be the flyback transformer failing. Is = > this a common problem for this model? I have heard of crafty technicians putting a drop of oil on the flyback transformer core to shut it up. This works only if the transformer is one of the laminated iron-core types. Ferrite-core types, obviously, won't benefit from this trick. In general, Wyse terminals, whose sole raison detre is "CHEEP", have all had a short life span. Regarding the dim screens: if adjusting the internal brightness control will brighten the screen, then good for you :) . If not, then it is probably that the electron gun in the CRT is used up. TV repair technicians used to use another trick I just remembered: they'd connect a variable voltage (a bench power supply) to the heater element pins at the back of the CRT and crank it up (experience and wisdom determined how much) for a while (ditto, for how long). This would burn off the deposits on the heater element, which would result in increased brightness for a (VERY variable) period of time. Good luck. Enjoy, Dave ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair,sci.electronics Path: cs.utk.edu!news.msfc.nasa.gov!newsfeed.internetmci.com!news.mathworks.com !news.kei.com!eff!news.duke.edu!godot.cc.duq.edu!newsfeed.pitt.edu!dsinc !ub!library.erc.clarkson.edu!multiverse!usenet From: "Samuel M. Goldwasser" Subject: Re: Viewsonic 4 horz output transistor? Date: 17 Jul 1995 01:26:02 GMT Organization: Picker International Lines: 26 Message-ID: <3uce7a$pu4@sauron.multiverse.com> References: <3ucb7d$kd8@osa.osa.com.au> To: cjh@osa.com.au cjh@osa.com.au (Clifford Heath) wrote: >I have been asked to repair a "Viewsonic 4" VGA monitor which has seriously >popped its horizontal output transistor. I believe it was a PNP type, >in a resin package about 3/4" by 1/2" by 3/16" (I don't know the name of >this package type - do you?). Unfortunately the label is burnt - can >anyone help me with identifying the type - I think it says "D" followed >by four digits? Otherwise can anyone let me know what Hfe and Vce specs >are required for this transistor? FYI, most horizontal output transistors are NPN bipolar. The 'D' would mean 2SDXXXX. 2SD is always NPN. The package is called TOP-3 or some variation on this. Unfortunately, that is as far as I can go. For testing, you can try a variety of replacements including probably (I will not pay if these blow up) 2SD1428, 2SD1652, 2SD1556, 2SD1403. The first three have internal damper diodes, the last does not. If you have an external damper diode, then it should nto mattter. There are many others - I just picked these out of the MCM catalog. I am not saying to use any of these necessarily as a permenant replacement, but for testing to determine what if anything else is fried, they should be fine. You can even use a TO3 cased transistor with similar ratings if you have one for testing. --- sam ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!usenet.eel.ufl.edu !news.cybercom.net!news.mathworks.com!newshost.marcam.com!hookup !multiverse!usenet Lines: 25 Message-ID: <3uiu6e$p5h@sauron.multiverse.com> References: <18JUL199515451924@cats.ucis.vill.edu> NNTP-Posting-Host: 144.54.161.7 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 1.2b1 (Windows; U; 32bit) Organization: Picker International Date: 19 Jul 1995 12:35:26 GMT To: 135784960@cats.ucis.vill.edu From: "Samuel M. Goldwasser" Subject: Re: Monitor Vert. Size 135784960@cats.ucis.vill.edu (fuzzy bunny) wrote: > >I have been having some difficulties with my monitor. (It acts up with other >computer's as well, so it is not the video card.) The monitor is a 15=inch >SVGA job that works fine for about half an hour. At this point, the vertical >hold seems to get worse and worse. First the screen starts shaking up and >down, >then the size of the screen shrinks to the middle third of the monitor. The >really weird thing is that when I reset the system, the startup screen(the >one with the energy saver star and memory test) is the right size and does not >shake. As soon as the screen changes, however, it is right back to the >smaller size. I did not see any physical damage to the board inside the >monitor >Has anyone else had a problem like this? How did you solve it? Any ideas of >what to check on inside?(I'm an EE, not afraid to pull parts and solder in new >ones.) Any help would be greatly appreciated. Assuming you are not running at an excessive vertical scan rate as someone else suggests, you probably have a bad cap or other component. Get a can of 'cold spray' or 'circuit chiller' and use it to cool each of the parts in the vertical section and power supply. Just a little squirt - wait a few seconds to see if there is any effect. Be careful in there - line voltage and high voltage. --- sam ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!news.msfc.nasa.gov!newsfeed.internetmci.com!news.mathworks.com !news.kei.com!newshost.marcam.com!hookup!multiverse!usenet From: "Samuel M. Goldwasser" Subject: Re: Jittery Monitors Date: 27 Jul 1995 12:15:57 GMT Organization: Picker International Lines: 20 Message-ID: <3v801t$b0u@sauron.multiverse.com> References: <3v7u39$2r0@cantua.canterbury.ac.nz> To: knoxcj@elec.canterbury.ac.nz knoxcj@elec.canterbury.ac.nz (c.j. knox) wrote: > >G'day. I have several old computers, some of which have unstable >monitors (VDUs) - they change the size of the text at random. >Have had a look at the capacitors, and none are obviously damaged/aged. >Would some kind soul suggest a solution? Neither myself nor my test >equipment are built for high voltages. Check for bad/cold solder connections, clean and reseat internal connectors, etc. Jittery unstable displays are more likely due to intermittent connections than bad components. Could also be excessive dirt/dust/crud buildup causing intermittent corona/arcing but this is less likely if there are no other symptoms. Most likely places for bad connections are around the pins of large components like power transistors, power resistors, transformers, and connectors. --- sam ////////////////////////////////////////////////////////////////////////////// Sprague Magnetics, Inc. Parts supplier and depot repair of computer peripherals, professional audio and professional film/video equipment. Web site at http://www.earthlink.net/~sprague-magnetics/ Conventional contact information: Sprague Magnetics, Inc. 15720 Stagg Street Van Nuys, CA 91406 +1 818/994-6602 ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!news.msfc.nasa.gov!elroy.jpl.nasa.gov!swrinde !howland.reston.ans.net!math.ohio-state.edu!newsfeed.acns.nwu.edu !uicvm.uic.edu!u54294 Organization: University of Illinois at Chicago, ADN Computer Center Date: Wed, 9 Aug 1995 13:44:45 CDT From: Message-ID: <95221.134445U54294@uicvm.uic.edu> Subject: Why terms lose setup info? Lines: 13 I have a collection of Wyse 60's, 160's and ADDS 4000/260's. Periodically some of them lose some parts of their setup information. I thought that it might be cosmic rays, spurious transmissions from aliens, or some other semi-random event, until it started happening to MY terminal. Since I am the system admin, the problem must now be addressed ;) Sooo... Does this happen at your site? Is it concentrated in a specific building or is it goegraphically random (like it is here)? Are specific terminal models or brands more subject to this than others? What's a mother to do? Thanks for your time....Nick G. +------------------------------+----------------------------------------+ | Just another roller-bearing | Nick Geovanis U54294@uicvm.uic.edu | | ...in the Data Warehouse | Unix software and sysadmin | +------------------------------+----------------------------------------+ ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!news.msfc.nasa.gov!newsfeed.internetmci.com !news.sprintlink.net!howland.reston.ans.net!news-e1a.megaweb.com !newstf01.news.aol.com!uunet!in2.uu.net!inews.intel.com !spectre.sc.intel.com!news From: Bennet Wong Subject: Re: Why terms lose setup info? Date: 9 Aug 1995 21:19:51 GMT Organization: Intel Corporation Lines: 35 Message-ID: <40b8pn$qk0@itnews.sc.intel.com> References: <95221.134445U54294@uicvm.uic.edu> Some areas you should look into: 1. How old is the terminal? Most terminal used a battery backup RAM to store setup. The avg. life is around 3 yrs. 2. Does user go in anc change the setup w/o letting you know? Did you remember to change and SAVE the setup? 3. Some setup value can be change by an escape sequence (cursor on/off .. etc.) Do you have any progarm that will issue command like this? For example, if your editor sends a change-cursor command during its init cycle and then you go into setup and change other setting, save and exit. Your cursor setting will be change and save also. 4. May be it is a bug in the Firmware, check with your dealer. 5. Sometime dirty power will cause the setup RAM to fail. If the problem happen in the same location over and over again you may want to swicth location and try again. 6. Very powerful electric dischage close to the terminal will also cause problem. I hope the info is helpful. If you want to know why I know so much. I used to work as the Mgr for Technical Support and SQA at Wyse. I am also a Sr. F/W engineer before I switch to a management role. Have fun. -- Bennet Wong Intel Corporation Internet: bennet_wong@ccm.sc.intel.com Disclaimer: Unofficial, personal *opinion*. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!gatech!news.mathworks.com!newsfeed.internetmci.com!psgrain !news.tek.com!sptekwv2!boots From: boots@sptekwv2.wv.tek.com (Darrell Irvin;685-2277;60-850;;sptekwv2) Subject: Re: Why terms lose setup info? Date: 15 Aug 1995 19:44:59 GMT Organization: Tektronix, Inc., Beaverton, OR Lines: 47 Sender: boots@sptekwv2 (Darrell Irvin;685-2277;60-850;;sptekwv2) Message-ID: <40qtfr$jtg@goodnews.wv.tek.com> References: <95221.134445U54294@uicvm.uic.edu> <40jrd2$qfm@nexus.polaris.net> Reply-To: boots@orca.wv.tek.com NNTP-Posting-Host: sptekwv2.wv.tek.com In article <40jrd2$qfm@nexus.polaris.net>, waters@polaris.net (Jonathan Waters) writes: |> In article <95221.134445U54294@uicvm.uic.edu>, says: |> > |> >I have a collection of Wyse 60's, 160's and ADDS 4000/260's. Periodically |> >some of them lose some parts of their setup information. I thought that |> >it might be cosmic rays, spurious transmissions from aliens, or some other |> >semi-random event, until it started happening to MY terminal. Since |> >I am the system admin, the problem must now be addressed ;) Sooo... |> >Does this happen at your site? Is it concentrated in a specific building |> >or is it goegraphically random (like it is here)? Are specific terminal |> >models or brands more subject to this than others? What's a mother to do? |> >Thanks for your time....Nick G. |> >+------------------------------+----------------------------------------+ |> >| Just another roller-bearing | Nick Geovanis U54294@uicvm.uic.edu | |> >| ...in the Data Warehouse | Unix software and sysadmin | |> >+------------------------------+----------------------------------------+ |> |> The problem usually lies in the type of Non Volatile memory (NVRAM) used |> to store the options. |> This type of terminal usually has a CMOS memory, with a battery backup. |> If the reset circuit "jerks" the control lines leading to the CMOS, it can |> cause what the CMOS thinks is a write pulse. Since the data and address lines |> are undefined at that point, weird things occur. |> |> The other reason may be pure and simple bugs in the software (firmware) |> that control these devices. |> |> I was head of R&D for a terminal manufacturer for some years, and know |> every way of lousing up setup options! |> |> Jonthan As a design engineer who did terminals for may years I can think of another potential problem (assuming good design in the first place). We always took great care to prevent spurious write pulses on power up. The battery can go bad from age, heat, etc. If your terminals are several years old this may be the problem. If it is a silver oxide or lithium cell in a holder simply replace it. It it is soldered it is a little more difficult. NiCad batteries are bad about dying of old age. -- ========================================================= = Darrell Boots Irvin boots@orca.WV.TEK.COM = = Network Displays Engineering = = Tektronix Inc. = ========================================================= ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!gatech!news.mathworks.com!transfer.stratus.com!xylogics.com !xylogics.com!not-for-mail Lines: 33 Message-ID: <40sln8$hle@newhub.xylogics.com> References: <95221.134445U54294@uicvm.uic.edu> <40jrd2$qfm@nexus.polaris.net> <40qtfr$jtg@goodnews.wv.tek.com> Reply-To: carlson@xylogics.com Date: 16 Aug 1995 07:44:40 -0400 Organization: Xylogics Incorporated From: carlson@xylogics.com (James Carlson) Subject: Re: Why terms lose setup info? In article <40qtfr$jtg@goodnews.wv.tek.com>, boots@sptekwv2.wv.tek.com (Darrell Irvin;685-2277;60-850;;sptekwv2) writes: |> In article <40jrd2$qfm@nexus.polaris.net>, waters@polaris.net (Jonathan Waters) writes: |> |> In article <95221.134445U54294@uicvm.uic.edu>, says: |> |> > |> |> >I have a collection of Wyse 60's, 160's and ADDS 4000/260's. Periodically |> |> >some of them lose some parts of their setup information. I thought that [...] |> |> I was head of R&D for a terminal manufacturer for some years, and know |> |> every way of lousing up setup options! [...] |> |> As a design engineer who did terminals for may years I can think of another |> potential problem (assuming good design in the first place). We always took [...] As yet another engineer who designed terminals in a previous job, we *never* used CMOS RAMs. The batteries were too expensive and unreliable. We used serial EEROMs instead for parameter storage. These things can go bad, though, if subjected to extreme heat or many thousands of "write" operations. I'd personally be very surprised to find battery-backed RAM in those terminals. I'd start looking for an 8-pin dip in an corner of the board, with no connections to anything interesting (like video or keyboard) and no comprehensible markings. If shorting a couple of pins on this device during power-up causes the terminal to lose the config information, then that's probably it ... -- James Carlson Tel: +1 617 272 8140 Annex Software Support / Xylogics, Inc. +1 800 225 3317 53 Third Avenue / Burlington MA 01803-4491 Fax: +1 617 272 2618 ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.os.vms Organization: Info-Vax<==>Comp.Os.Vms Gateway Message-ID: <01JB7X43LFHE000OZ3@IST.CERIST.DZ> Date: Sat, 15 May 1999 08:22:21 +0000 (GMT) From: L. Benchabane Subject: Re: NVR error/failure with VT220? At 20:28 13/05/99 -0600, "Mark" wrote: > >Anyone here who might recall a failure of the non-volatile memory of >a VT220, i.e. loss of the saved Set-Up configuration for >modem-connected terminal? > >The message came up today, but a reentry of whatever settings it >takes to make this beauty work as my modem connection to the campus >VAX made everything OK again. > >Is this perhaps a sign of a VT220 about to fail completely? > > > Mark (Please note, I did _not_ pose this to "old"-timers :-) The NV RAm is located on E17 in logic board. It's a 2212 RAM 256x4 . DEC part number is 2120263-01. NVR failure dont mean that your VT220 is close to die ....... L.BENCHABANE ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!watson.math.niu.edu !mp.cs.niu.edu!vixen.cso.uiuc.edu!howland.reston.ans.net !newsfeed.internetmci.com!news.sprintlink.net!su3.in.net!usenet From: jstermer@in.net (Jay Stermer) Subject: Re: Problem with IBM 8515 monitor Date: Sat, 09 Sep 1995 23:38:08 GMT Organization: John Jay Stermer, B.S.E.E. Lines: 16 Message-ID: <42t50p$adb@su3.in.net> References: <1995Sep4.144101@tudedv.et.tudelft.nl> <1995Sep6.214212@tudedv.et.tudelft.nl> Reply-To: jstermer@in.net reggermont@et.tudelft.nl (Robbert Eggermont) wrote: >> I have an IBM 8515 monitor which has a vertical deflector problem. >I suspect the TDA2030 (I think anyway this is the chip that takes care >of the vertical deflection). Is there a way to tell if this chip is >defective, without having to turn the monitor on? >Any hints? Most vertical output IC's are fed from the flyback transformer. Inspect that area for burned resistors. Many times the diode which rectifies the voltage will short which then opens the fusible resistor that feeds it. If you find this, you should always replace the IC while you're at it since it's probably damaged from the burst of unfiltered AC when the diode failed. ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!usenet.eel.ufl.edu!gatech !news.mathworks.com!tank.news.pipex.net!pipex!news.sprintlink.net!mv!usenet From: bachman@anatek.mv.com Subject: Re: Gateway CrystalScan starts to wiggle Message-ID: Nntp-Posting-Host: anatek.mv.com Sender: usenet@mv.mv.com (Paul Hurley) Organization: AnaTek Corp., Monitor Repair Data, http://www.anatekcorp.com/ Date: Wed, 27 Sep 1995 17:28:14 GMT Followup-To: choiw1@intac.com Lines: 10 Check R331, 91Kohm, 1 watt. If it is >95Kohms oscillation can occur. This monitor is covered in our monitor repair database at http://www.anatekcorp.com/repair.htm _____________________________ John Bachman AnaTek Corporation Monitor Repair Data http://www.anatekcorp.com/repair.htm ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!usenet.eel.ufl.edu !news.mathworks.com!news.kei.com!simtel!news.sprintlink.net !malgudi.oar.net!picker!central.picker.com!sam From: sam@colossus (Sam Goldwasser) Subject: Re: Sony KP-5020 Projection TV Picture Shrunk In-Reply-To: craigr@magicnet.net's message of 24 Sep 1995 08:02:54 GMT Message-ID: Sender: news@picker.com Nntp-Posting-Host: 144.54.160.15 Organization: Picker International, Inc. References: <4433be$org@comet.magicnet.net> Date: Sun, 24 Sep 1995 20:50:49 GMT Lines: 146 In article <4433be$org@comet.magicnet.net>, craigr@magicnet.net (Craig H. Rogers) writes: > > I have an old Sony front projection set that i have had for years. > It hadn't been plugged in since 1991 and I plugged it in two weeks > ago, it fired up ok and I focused and converged the picture fine. > It worked ok for the last two weeks and then I left it on for a few > hours the other day, and coming home I saw the picture had shrunk > horizontally to about 75% of the screen size and the focus (electronic) > was a bit fuzzy and of course the convergence went out also. I do > not have much if any experience with TV's other than owning a BarcoData > that was the greatest set at blowing up flybacks, quads, and splitters. Was it stable at this reduced size? No jitters that might indicate a bad connection? Does whacking it have any effect? Some other possibilities: bad capacitor or power supply problem. > I haven't called Sony yet to see if they would still happen to have > a schematic, I shall do that Monday, unless someone here knows of > a place to call for out-of-production schematics. What I wish to > know is the probably cause of this problem, why it occured, and > what to expect as far as repair and future problems. I would have > assumed (probably incorrectly) that the horizontal deflection was low > due to some loss in the HV circuit, possibly leaky/going bad quad? This is a possibility but such a fault would usually produce other symptoms like blown fuses or fried transistors. > The only other problem that I forsee other than being ignorant is > attempting to probe the HV circuit (if necessary). I have a Fluke > 80K-6 HV probe (6kV PK MAX) connected to my Fluke 87, but that's about > the limit of it. I hope I do not have to purchase a 40KV+ probe for > this attempted repair, I am sure that would not be cost effective. There will probably be no need to probe the HV. However, I do hope you are aware of the safety issues involved in probing something like a TV - especially a projection TV. I will include them below. > I would have taken to a real tech and have them repair it, but after > paying for replacement quads, spitters, etc for the Barco at outrageous > prices, I would just like to give myself "a second opinion" as to > possible problems. Thank you very much. If the only problem is a reduced horizontal size, then you probably have a bad connection, dried up capacitor, or low power problem. I don't know if Howard SAMs has service info for your set but that would be the first place to check - your local large public library or an electronics distributor. --- sam General Safety Guidelines when working on line powered equipment including: TVs, monitors, and microwave ovens. These guidelines are to protect you from potentially deadly electrical shock hazards as well as the equipment from accidental damage. Note that the danger to you is not only in your body providing a conducting path, particularly through your heart. Any involuntary muscle contractions caused by a shock, while perhaps harmless in themselves, may cause collateral damage - there are many sharp edges inside this type of equipment as well as other electrically live parts you may contact accidentally. The purpose of this set of guidelines is not to frighten you but rather to make you aware of the appropriate precautions. Repair of TVs, monitors, microwave ovens, and other consumer and industrial equipment can be both rewarding and economical. Just be sure that it is also safe! * Don't work alone - in the event of an emergency another person's presence may be essential. * Always keep one hand in your pocket when anywhere around a powered line-connected or high voltage system. * Wear rubber bottom shoes or sneakers. * Wear eye protection - large plastic lensed eyeglasses or safety goggles. * Don't wear any jewelry or other articles that could accidentally contact circuitry and conduct current, or get caught in moving parts. * Set up your work area away from possible grounds that you may accidentally contact. * Know your equipment: TVs and monitors may use parts of the metal chassis as ground return yet the chassis may be electrically live with respect to the earth ground of the AC line. Microwave ovens use the chassis as ground return for the high voltage. In addition, do not assume that the chassis is a suitable ground for your test equipment! * If circuit boards need to be removed from their mountings, put insulating material between the boards and anything they may short to. Hold them in place with string or electrical tape. Prop them up with insulation sticks - plastic or wood. * If you need to probe, solder, or otherwise touch circuits with power off, discharge (across) large power supply filter capacitors with a 2 W or greater resistor of 100-500 ohms/V approximate value (e.g., for a 200 V capacitor, use a 20K-100K ohm resistor). Monitor while discharging and/or verify that there is no residual charge with a suitable voltmeter. In a TV or monitor, if you are removing the high voltage connection to the CRT (to replace the flyback transformer for example) first discharge the CRT contact (under the insulating cup at the end of the fat red wire). Use a 1M-10M ohm 1W or greater wattage resistor on the end of an insulating stick or the probe of a high voltage meter. Discharge to the metal frame which is connected to the outside of the CRT. * For TVs and monitors in particular, there is the additional danger of CRT implosion - take care not to bang the CRT envelope with your tools. An implosion will scatter shards of glass at high velocity in every direction. There is several tons of force attempting to crush the typical CRT. Always wear eye protection. * Connect/disconnect any test leads with the equipment unpowered and unplugged. Use clip leads or solder temporary wires to reach cramped locations or difficult to access locations. * If you must probe live, put electrical tape over all but the last 1/16" of the test probes to avoid the possibility of an accidental short which could cause damage to various components. Clip the reference end of the meter or scope to the appropriate ground return so that you need to only probe with one hand. * Perform as many tests as possible with power off and the equipment unplugged. For example, the semiconductors in the power supply section of a TV or monitor can be tested for short circuits with an ohmmeter. * Use an isolation transformer if there is any chance of contacting line connected circuits. A Variac(tm) is not an isolation transformer! The use of GFCI (Ground Fault Circuit Interrupter) protected outlet is a good idea but will not protect you from shock from many points in a line connected TV or monitor, or the high voltage side of a microwave oven, for example. A circuit breaker is too slow and insensitive to provide any protection for you or in many cases, your equipment. These devices may save your scope probe ground should you accidently connect it to a live chassis, however. * Don't attempt repair work when you are tired. Not only will you be more careless, but your primary diagnostic tool - deductive reasoning - will not be operating at full capacity. * Finally, never assume anything without checking it out for yourself! Don't take shortcuts! ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!usenet.eel.ufl.edu !newsfeed.internetmci.com!news.mathworks.com!tank.news.pipex.net !pipex!news.sprintlink.net!in2.uu.net!pipeline!psinntp!psinntp !psinntp!voder!berlioz!news From: grohe@galaxy.nsc.com (Paul Grohe) Subject: Re: ecg semiconductor crossreference X-Nntp-Posting-Host: mil Message-ID: Sender: news@berlioz.nsc.com (UseNet News account) Organization: National Semiconductor X-Newsreader: WinVN 0.93.14 References: <44062n$m08@ixnews3.ix.netcom.com> Mime-Version: 1.0 Date: Mon, 25 Sep 1995 20:18:15 GMT Lines: 74 In article <44062n$m08@ixnews3.ix.netcom.com>, gabriel lara says... > >is phillips ecg semiconductor cross reference or similiar program in >share ware available on disk?? Yes, and believe it or not, AOL actually has somthing usefull... If you have Access to AOL (10 free hrs???) look in the: COMPUTING -> SOFTWARE SEARCH and search for NTE ---------- Description clipped from AOL search form ----------------- File: NTE.ZIP (2037627 bytes) DL time (14400 baud): < 37 minutes Download count: 594 AUTHOR: NTE Electronics and Cybersoft Inc. EQUIPMENT: Hard Drive w/3 megs free, HD Floppy for install, Mouse recommended NEEDS: An UnZIPing Program Keywords: Cybersoft, Electronics, Parts, Catalog, Relay Type: Freely Distributed Version: 01/01/92 A cross referenced database/catalog of electronic components from NTE Electronics. Search for either relays or semiconductors. Give entire Industry Device number (ECG number) or partial number. The program displays the component (or a list of all matching companents if a partial number is given). The Industry Device number, NTE Electronics device number, and a brief description/comment are shown. Example: when searching for partial relay number 121, 59 entries were listed. One was: Industry #HE-721A1210, NTE #R57-ID.5-12D, Described as- SPST-NO 0.5A DC 12V DIP/Clamp Diode Information can be viewed onscreen or printed. Listings of NTE sales offices are included. Online help is available and the program is mouse aware. Note: After downloading, copy all files except NTEPAC1 to a high density floppy. Copy NTEPAC1 to a second HD floppy. Put the first floppy in the drive, change to that drive and type INSTALL. When asked, change to the second disk. The program will be installed to C:\NTE unless directed elsewhere. If you don't have a HD floppy but still want to use the program, you can install it from a subdirectory on your hard drive using the DOS SUBST command prior to running install (SUBST A: C:\DIR where DIR is the name of the directory you will install from. You should still tell install that A: is the source. Remember to SUBST A: A: when done.). To run, enter: NTE Documentation: Within the program --------- Back to me ---------------------------------- You now have 9.5 hrs left.. Regards, Paul Grohe --------------------------------------------------------------- Paul Grohe National Semiconductor Corp. Sr. Electronics Technician 2900 Semiconductor Drive New Products Engineering Group Mail Stop C2693 Email: grohe@galaxy.nsc.com Santa Clara, CA. 95052-8090 USA (408) 721-7389 Tel NSC datasheets online at: (408) 721-2513 Fax http:\\www.nsc.com\ - Ethernet (n): something used to catch the etherbunny Press any key to continue or any other key to quit... --------------------------------------------------------------- ////////////////////////////////////////////////////////////////////////////// Article 16378 of sci.electronics.repair: Path: cs.utk.edu!gatech!news.mathworks.com!zombie.ncsc.mil!simtel!news.sprintlink.net!dfw.nkn.net!usenet From: Jeff Luebke Newsgroups: sci.electronics,sci.electronics.repair Subject: Re: WTB IRFP350, IRFP350, IRF740 Date: 7 Oct 1995 17:09:04 GMT Organization: Plano Components Lines: 16 Message-ID: <456c7g$gud@dfw.nkn.net> References: <454u75$qmk@charles.cdec.polymtl.ca> NNTP-Posting-Host: fastlane.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 1.22 (Windows; I; 32bit) To: bassman@step.polymtl.ca Xref: cs.utk.edu sci.electronics:151583 sci.electronics.repair:16378 We can help you with mosfets as well as other semiconductors considered hard to locate.We are semiconductor brokers located in the Dallas Texas area. Contact us via email,fax or phone, indicating your quantities required, your approved manufacturers and any other specific requests and we will follow thru... The IRFP350's are tougher to locate than the 740's...but we should be able to locate at least small quantities on both. Feel free to contact us with any questions, or comments Thanks Jeff Luebke Plano Components jeff@plano.com http://www.plano.com/homepages/jeff/plano 214-516-0873 voice 214-423-3790 fax ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: cs.utk.edu!willis.cis.uab.edu!nntp.msstate.edu!cssun.mathcs.emory.edu !swrinde!newsfeed.internetmci.com!in1.uu.net!brighton.openmarket.com !decwrl!tribune.usask.ca!canopus.cc.umanitoba.ca!news.magic.mb.ca!usenet Organization: Microtrader Canada Lines: 22 Message-ID: <496247$19k@aahz.magic.mb.ca> References: <4934e5$9km@buffnet2.buffnet.net> To: cyberman@buffnet.net Date: 25 Nov 1995 03:21:43 GMT From: "Brent Crighton, Microtrader Canada" Subject: Re: vt220 whine poof no image :) I hate to tell you but that means the high voltage power supply Just fried. We can fix for $75.00 but cheaper to send you replacement used, warrantied terminal for $85.00 -- Brent Crighton, Owner MICROTRADER Canada Preowned Computer Systems and Parts 2229 Henderson Highway Winnipeg, Manitoba, Canada Voice....204-339-3999 Fax......204-334-6599 Direct...204-227-4089 www......http://www.magic.mb.ca:80/~microt/ email....microt@magic.mb.ca ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: utkcs2!stc06.ctd.ornl.gov!howland.erols.net!news.sprintlink.net !news-peer.sprintlink.net!uunet!in3.uu.net!en.com!usenet Message-ID: <55j104$9ur@antares.en.com> Date: Sun, 03 Nov 1996 23:58:43 GMT From: ncd@en.com Newsgroups: comp.terminals Subject: VT220 repairs We repair VT220 terminals $50 flat rate repair for the monitor $25 flat rate repair for the keyboard Warranted 90 days E-mail ncd@en.com or call 216-953-4488 John [northern Ohio] ////////////////////////////////////////////////////////////////////////////// Article 5958 of comp.terminals: Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!uwm.edu!vixen.cso.uiuc.edu!newsfeed.internetmci.com!news.sprintlink.net!new-news.sprintlink.net!jupiter.planet.net!saturn.planet.net!edpaolo From: edpaolo@planet.net (E. Paolo) Newsgroups: sci.electronics.repair,comp.terminals,sci.electronics.components Subject: Looking for LH-2440 video/chroma module Date: 28 Jun 1996 17:50:55 GMT Organization: Planet Access Networks - Stanhope, NJ Lines: 13 Message-ID: <4r161v$gpf@jupiter.planet.net> NNTP-Posting-Host: saturn.planet.net Keywords: LH-2440 X-Newsreader: TIN [version 1.2 PL2] Xref: cs.utk.edu sci.electronics.repair:28678 comp.terminals:5958 sci.electronics.components:6126 The LH-2440 chroma video module used on the Tektronix monitors. This part is not made anymore and On-line Tech has it bit with a large min. qty amount. Have checked CCS, MCM, DALBANA and Allied. If anyone who use to repair the Tektronix monitors, who might have a one of thes modules for sale, contact me. Or if you know of a source of these modules made by Nat. Semi., who doesn't have a pin/pin replacement for these, let mw know. EdDataFix edpaolo@saturn.planet.net ////////////////////////////////////////////////////////////////////////////// Path: cs.utk.edu!gatech!news.mathworks.com!zombie.ncsc.mil!nntp.coast.net !netnews.worldnet.att.net!ix.netcom.com!news Newsgroups: tn.computing,tn.general,vu.general,misc.for-sale.mac, comp.sys.mac.hardware.video,comp.sys.hardware.misc, misc.forsale.computers.mac,misc.forsale.computers.monitors misc.forsale.computers.mac-specific.systems, Date: Sun, 23 Jun 1996 00:42:59 -0400 Message-ID: <31CCCB53.12A0@ix.netcom.com> References: <4q6iaj$fmn@news.vanderbilt.edu> NNTP-Posting-Host: frd-md1-16.ix.netcom.com To: flackcj@ctrvax.vanderbilt.edu From: "D. M. West" Subject: Re: Repair of Mac Monitor? -- Help needed I've worked on two of those that had a shorted degaussing coil. That would blow a fuse thats soldered on the cca. First find the degauss coil connection and remove, then solder fuse holder accross blown fuse, snap in new fuse. If it comes up, the colors may be a mess. If you don't have acess to a hand held degauss coil, a local TV shop would have one. Only takes about two min to degauss. Do't place near other strong electrical feild and things sjould be ok, but may need degaussing every once in a while. Could be another problem, but this fix is easy to try. Don ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!news.msfc.nasa.gov!newsfeed.internetmci.com!news.mathworks.com !news-res.gsl.net!news.gsl.net!news.uoregon.edu!news.islandnet.com!usenet Date: Sun, 25 Aug 1996 13:52:18 -0700 Organization: Island Net in Victoria, B.C. Canada Message-ID: <3220BD02.2986@IslandNet.com> References: <4vp455$ol4@juliana.sprynet.com> NNTP-Posting-Host: i2-133.islandnet.com From: Jan Skirrow Subject: Re: looking for monitor schematics and parts tettra@sprynet.com wrote: > > Greetings > > I am looking for schematics for any and all types of monitors. I am > also looking for parts for any and all monitors (CRTs analogs and > such). If anyone knows of any companys who sell these schematics and > parts please let me know > > Thanks in advance > > Jeff MI Technologies has a large range of monitor schematics for sale. Pricey, but there may be little other option! Fax: 513-339-6344 Tel: 513-335-4560 ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair Path: cs.utk.edu!news.msfc.nasa.gov!newsfeed.internetmci.com!in2.uu.net !mint.net!news Date: Sat, 07 Sep 1996 22:24:56 -0400 Organization: Digiphonics Audio Laboratories Message-ID: <32322E78.18F0@mint.net> References: <322FBE72.7081@pacbell.net> Reply-To: bryboe@mint.net NNTP-Posting-Host: dialup-b-9.mint.net From: brian leeman Subject: Re: Sony Model 13TR25 - 13 inch receiver interminent tuner w6cjw@pacbell.net wrote: > > Would like to know if any users have discover why the tuner or tv signal > fails to work until the set has been on for about 10 minutes. This > problem shows up on the VHF channels - the UHF channels will work. A > number of the same vintage sets are starting to show the same problem. > Any suggestions would be most welcome. I have run into a few of these... In every case it has been due to one of the grounding "fan" leads that runs from the PCB to the metal case having a cold joint. It has always been the lead that fastens to the top of the case directly to the left of the AGC trimmer (looking at the trace side). These problems are gravy for techs, but it is a shame how poorly Sony executes the manufacture of their consumer electronics. Talk about mass produced junk... Sorry for the rant, but if you work on this stuff, you hafta agree!! Hope this helps & good luck!! Brian ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.periphs.printers,comp.sys.hp.hardware,sci.electronics.repair Path: utkcs2!stc06.ctd.ornl.gov!news.he.net!news.maxwell.syr.edu !cam-news-hub1.bbnplanet.com!su-news-hub1.bbnplanet.com !news.bbnplanet.com!csn!nntp-xfer-1.csn.net!ncar!ren Date: 8 May 1997 18:17:57 GMT Organization: Research Applications Program, NCAR, Boulder, CO USA Message-ID: <5kt5cl$f12$1@ncar.ucar.edu> References: <33666b7c.33635335@207.51.163.4> <336bc088.1130740@netnews.worldnet.att.net> NNTP-Posting-Host: 128.117.192.15 From: ren@rap.ucar.edu (Ren Tescher) Subject: Re: HP Service Stinks (was Re: HP 550C -or- Even tanks need repair!) In article , "Diane L. Roskar" writes: > > [snip] > This is not very good service at all!!! > An example of good product service is given by Sony: I can still get service > & repair parts for my 7 year old Sony Hi8 Video camera, over the phone -- as > an end-user consumer. You're saying Sony has great product service? You've obviously never tried to get parts/schematics/advice on any of the many Computer Monitors they've entered into Non-Disclosure Agreement (NDA) with Computer OEM's (e.g. Sun, SGI). I'm talking Sony models CPD-1790, GDM-1662 & GDM-1604 in particular. In that case, only a few companies approach the Sony Suck Factor, and probably no other manufacturer exceeds the SSF standard set by Sony. The real rip is, none of the OEM's are capable of repairing the Sony Monitors either! They just replace them. Please, use some other, 'realistic' example when referring to good customer service. -- Ren ////////////////////////////////////////////////////////////////////////////// Newsgroups: vmsnet.pdp-11 Path: cs.utk.edu!news.msfc.nasa.gov!news.sgi.com!news.mathworks.com!uunet !in3.uu.net!news.new-york.net!spcuna!spcvxb!terry Nntp-Posting-Host: spcvxa.spc.edu References: <199609301538.KAA15960@plains.nodak.edu> Sender: news@spcuna.spc.edu (Network News) Organization: St. Peter's College, US Date: Mon, 30 Sep 1996 20:27:05 GMT Message-ID: <1996Sep30.162705.1@spcvxb.spc.edu> From: terry@spcvxb.spc.edu (Terry Kennedy, Operations Mgr.) Subject: Re: Opening a VT220 In article <199609301538.KAA15960@plains.nodak.edu>, Todd Enders - WD0BCI writes: > > So, everything external has been checked, now I have to get inside the > thing. Trouble is, I've removed the obvious screws, the not-so-obvious > screws, and a few others. Still can't make the bloody thing come apart. > Now, I'm sure there's a neat trick involved, or I'll need something like > the case-cracking tool for the old Macintoshes, but there *has* to be a > way inside the blasted thing! There are 3 screws hidden under plastic caps, 1 on the back and 2 on the bottom. The caps are maybe 3/8" in diameter and are recessed into a plastic ridge. I use one of the tiny green-handled Xcelite screwdrivers to pry 'em out (I don't know if there's a better way) and then use a regular Philips screwdriver on the 3 screws that are revealed. Obligatory caution note: Dangerous high voltages inside - trained service personnel only. Terry Kennedy Operations Manager, Academic Computing terry@spcvxa.spc.edu St. Peter's College, Jersey City, NJ USA +1 201 915 9381 (voice) +1 201 435-3662 (FAX) ////////////////////////////////////////////////////////////////////////////// Newsgroups: vmsnet.pdp-11 Path: cs.utk.edu!gatech!csulb.edu!news.sgi.com!news.mathworks.com !howland.erols.net!cam-news-hub1.bbnplanet.com!cam-news-feed5.bbnplanet.com !umass.edu!nic.umass.edu!wilde.oit.umass.edu!not-for-mail Date: 1 Oct 1996 22:06:31 GMT Organization: University of Massachusetts, Amherst Message-ID: <52s4l7$mo5@nic.umass.edu> References: <199609301538.KAA15960@plains.nodak.edu> <52pd60$h4r@mars.hyperk.com> From: asvirsky@wilde.oit.umass.edu (Alexander R Svirsky) Subject: Re: Opening a VT220 If the keyboard doesn't light and the CRT does not fire up, it is possible that the problem is as simple as a broken power switch. I have had 3 VT220's with bad power switches. Swapping switches out of VT220's with bad tubes or boards always worked for me. Good luck, Alex -- Alexander Svirsky N1PRW University of Massachusetts asvirsky@student.umass.edu Amherst ////////////////////////////////////////////////////////////////////////////// Newsgroups: vmsnet.pdp-11 Path: cs.utk.edu!cssun.mathcs.emory.edu!gatech!csulb.edu!news.sgi.com !howland.erols.net!EU.net!usenet2.news.uk.psi.net!uknet !usenet1.news.uk.psi.net!uknet!uknet!lyra.csx.cam.ac.uk!ard12 Date: 30 Sep 1996 18:56:54 GMT Organization: University of Cambridge, England Message-ID: <52p55m$mqu@lyra.csx.cam.ac.uk> NNTP-Posting-Host: club.eng.cam.ac.uk From: ard12@eng.cam.ac.uk (A.R. Duell) Subject: Re: Opening a VT220 shoppa@alph02.triumf.ca (Tim Shoppa) writes: >> So, everything external has been checked, now I have to get inside the >>thing. Trouble is, I've removed the obvious screws, the not-so-obvious >>screws, and a few others. Still can't make the bloody thing come apart. >>Now, I'm sure there's a neat trick involved, or I'll need something like >>the case-cracking tool for the old Macintoshes, but there *has* to be a >>way inside the blasted thing! The '220 is the console terminal for my 11/10, >>and I don't have anything else short of an old DECwriter that'll do current >>loop, so I pretty well need the '220 back on line. Any help would be greatly >>appreciated! Many thanks!!! >Screws? As I recall, you only have to remove one screw. It's on the No, you're thinking of the VR201 (which has only 1 screw on the rear). The VT220 (I've opened a lot of them) is held together by 3 screws, all covered by those white plastic domes. One on the rear and two on the bottom, I think. You unplug all the cables, stand the thing on its front, flick off the domes, undo the screws, and pull the shell off. >back, centered left-right, near the top, and usually covered by a >white plastic dome which you have to pop off. The cover now ought to >slide right off the rear. If you're opening a VR201 (the PRO/DECmate/Rainbow mono monitor), don't forget to extend the leg fully before you start. Otherwise the case will not come off. >Sure beats the plastic "snap" connectors used to hold the top of >a VT100 on! Very few of those have survived intact over the >course of nearly 20 years... mainly because of techs who didn't >properly know how to disengage them. Those infernal things are the invention of the Devil :-(. They're used in some other DEC devices as well - the LA100 series springs to mind. I'd much prefer proper screws... Oh, and if the original poster can't fix his VT220, there are TTL level serial I/O signals on the 11/10 connector where you'd expect them. A little kludge using a MAX232 should let you hook up an RS232 terminal. Or, of course, you could search for the orignal IBM Async card, which, amazingly, had 20mA loop circuitry... >Tim. (shoppa@triumf.ca) -- -tony ard12@eng.cam.ac.uk The gates in my computer are AND,OR and NOT, not Bill ////////////////////////////////////////////////////////////////////////////// [regarding the Macintosh case-cracking tool] Newsgroups: alt.folklore.computers Date: 10 Apr 1997 08:52:20 GMT Message-ID: <5ii9o4$sbn@reader.seed.net.tw> From: dski@cameonet.cameo.com.tw Subject: Re: Opening a Mac (was Re: IBM PC vs. Apple ca. 1981) Jay R. Ashworth (jra@scfn.thpl.lib.fl.us) wrote -- > > Along with square bits, which have a name, too. "Robertson"? Right on the button. Full name: square-recess bits. Also called Robertson and Scrulox tips. Salvaged a pristine McMaster-Carr Supply Company catalog from the trash when the company next door moved out. "Serving Industry Since 1901" -- I can believe it. Nowhere do they say what kind of supply company M-C is. They hardly need to, with 2,963 pages of, of... *stuff*. Dan Strychalski ////////////////////////////////////////////////////////////////////////////// [here are other people's recollections about the Mac tool] Newsgroups: alt.folklore.computers Date: 8 Apr 1997 18:33:44 GMT Message-ID: <01bc444c$6cdc2020$0f02000a@grant> From: Grant Gischer Subject: Re: Opening a Mac (was Re: IBM PC vs. Apple ca. 1981) > : In article <33458224.0@131.162.2.91>, 016958j@news.acadiau.ca (Kenneth Jamer) writes: > > : >Torx screwdrivers ... hmm should have 10(ish) points and a flat top.. > : >cause I had a Buick that required one to change the headlamps. Had a > : >heck of a time finding one, eventually found a whole set of them > : >4 different sizes (and maybe different point counts ?). Could it be the > : >same thing? > : *10* points? My husband just showed me a couple of these (different sizes), > : and > : his have six points. (baffled look) > : Do Torx screwdrivers come with different point counts? I am basically > : totally clueless > : about most tools. My husband says that they're all six-point (but he > : does tend to be a > : bit arrogant (smile)). > > <*sheepish grin*> > umm six points is a possibility, When I was posting I remebered the T-10 > designator in a slightly strange way. I don't have any around at the > moment, but the more people say, the more Im sure I was mistaken. > I just got out my set (it has 8 sizes), and they all have six points. (Not to be confused with a hex/Allen wrench, which has six faces) It looks like a star of David, which I will attempt to graphically illustrate here: / \ _____/ \_____ \ / \ / / \ /____ ____\ \ / \ / Hope that helps. -- grantg@memes.com http://www.memes.com/~grantg Forsale Page: http://www.memes.com/~matt/compfs.html ////////////////////////////////////////////////////////////////////////////// Newsgroups: alt.folklore.computers Message-ID: <5ib7h9$vek@flood.weeg.uiowa.edu> Date: 7 Apr 1997 16:31:37 GMT From: "Douglas W. Jones,201H MLH,3193350740,3193382879" Subject: Re: Opening a Mac (was Re: IBM PC vs. Apple ca. 1981) From article <5ib4f0$ap4@tor-nn1-hb0.netcom.ca>, by seward@netcom.ca (John Savard): > > Bought an original Mac - screen is dead - for $15 at a thrift shop. > Can't find a long enough Torx in any hardware store - or, since hex > Torx bits are available, a slim enough holder for them. Bought a broken Mac SE (screen is dead) for $5 at a surplus outlet. Found another SE in a trash can, stripped of memory and disk drives. Found a "mac cracker" (Torx wrench) in pile of tools discarded by computer maintenance group. Found a diskette copy of MAC-OS 7.1 still in shrink-wrap at a surplus outlet for $5. The mac cracker is a standard hex Torx bit rammed into a piece of thin-wall steel tube with a flat blade welded to the hind end to make a T-shaped handle. The ramming operation distorted the end of the tube to the hex shape of the but end of the bit. The flat handle is also useful in "cracking" a mac because you can set the edge of it in the crack between the front and back halves of the case Net result? One working and useful Mac SE for my son, for almost nothing. Plus a spare power supply and motherboard. The dead screen was caused by a bad picture tube -- no vacuum. Doug Jones jones@cs.uiowa.edu ////////////////////////////////////////////////////////////////////////////// Newsgroups: vmsnet.pdp-11 Path: cs.utk.edu!gatech!csulb.edu!news.sgi.com!news.mathworks.com !www.nntp.primenet.com!nntp.primenet.com!howland.erols.net!EU.net !usenet2.news.uk.psi.net!uknet!usenet1.news.uk.psi.net!uknet!uknet !warwick!lyra.csx.cam.ac.uk!ard12 Date: 1 Oct 1996 16:27:58 GMT Organization: University of Cambridge, England Message-ID: <52rgqe$gvu@lyra.csx.cam.ac.uk> References: <199609301538.KAA15960@plains.nodak.edu> From: ard12@eng.cam.ac.uk (A.R. Duell) Subject: Re: Opening a VT220 Todd Enders - WD0BCI writes: > > After loaning out my venerable VT220 for some work-related activities, > it no longer does anything when turned on. Checked the fuse, and it was OK, > plus, mains voltage appeared at the fuse socket. I assume you have a keyboard connected, and that the LED's on that don't blink when you turn the terminal on. If that's the case, then it sounds like a power supply problem. From what I recall, the VT220 PSU is a fairly simple thing with a line frequency transformer bolted to the chassis feeding low-voltage AC to the video board. When you've got the cover off, I'd check the output(s) of the transformer first, and then check the power pins of the chips on the digital board. I don't have the VT220 printset (does such a thing exist?), but I never had any problems fixign them. >Todd enders@plains.nodak.edu -- -tony ard12@eng.cam.ac.uk The gates in my computer are AND,OR and NOT, not Bill ////////////////////////////////////////////////////////////////////////////// Newsgroups: alt.folklore.computers Path: utkcs2!stc06.ctd.ornl.gov!fnnews.fnal.gov!news.imsa.edu!chi-news.cic.net !arclight.uoregon.edu!su-news-hub1.bbnplanet.com !cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!worldnet.att.net!uunet !in2.uu.net!192.89.123.24!nntp.inet.fi!news.sci.fi!usenet Date: Sun, 16 Mar 1997 06:35:46 GMT Organization: Scifi Communications International X-Contact: helpdesk@sci.fi, +358 3 2899111, http://www.sci.fi/ Message-ID: <333681ee.1296983714@news.sci.fi> References: <5ge6hr$l3b@reader.seed.net.tw> NNTP-Posting-Host: ccclv.dyn.sci.fi From: keinanen@sci.fi (Paul Keindnen) Subject: VT-220 (Was: Pre-1988 Windows ECS) dski@cameonet.cameo.com.tw wrote: >From dski@cameonet.cameo.com.tw (sound familiar?) came the query -- > >> Anyone know what Windows used for an extended character set before >> ISO 8859-1 came along? > >Well, I seem to have found an answer to my own question -- in the same >German article I asked folks to translate part of a few months ago. I >don't think I thanked everyone then, so I now extend thanks to all. I >daren't make another request, so I'll just post the relevant passage. >Here are some URLs where the full article can be found: > >http://www.nadir.org/NA/WebEntry/8859-de.txt >http://www.sax.de/text/README.umlauts >http://vops2.avl.co.at:8001/www/faq/de-usenet-umlaute.txt > >And here's the part that mentions the original Windross charset: >- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - >Im Jahre 1981 kam der IBM PC mit einer 8-bit Zeichenkodierung heraus. >Leider schienen die Entwickler bei der Reihenfolge der Zeichen >gewuerfelt zu haben. Das Ergebnis: die IBM Codepage 437. > >Im Jahre 1982 wurden die ersten DEC VT220 und VT240 auf den >Markt gebracht. Die hatten einen Vorlaeufer von ISO 8859-1 >im Einsatz: DEC MCS (Multinational Character Set). All the documentation that came with the VT-220 has a copyright date for the first edition as August 1983, so the 1982 as the release year for VT-220 and VT-240 sounds a bit early. In addition to the MCS character set the VT-220 had some other oddities in the serial line interface. Due to the signal and protective ground arrangement, it produced much more ground loop problems than the VT-100. The serial line transceivers were according to RS-423, which had a lower output voltage swing than RS-232, but still within the input specification for RS-232, so the terminal was compatible with older equipment using the original RS-232 transceivers. Some sources claimed that the RS-423 was the unbalanced version of the symmetrical RS-422, but I have newer seen the specifications for both of these standards. Anyway, the RS-423 transceivers on early VT-220s were quite fragile, since all but one of our VT-220 failed within the warranty period. Apparently this was a common problem, since the DEC field service engineer always first installed a socket and then inserted the transceiver. After a few visits, he gave us a tube of those transceivers to be used, if the repaired terminal would once again failed. We were quite disappointed that the last one from this batch did not fail during the warranty period, to get the socket installed. Yes, you guessed, that one failed a month after the warranty period, so it was time to fire up the soldering iron, fortunately, there were some chips left in the tube we got earlier. Later versions of the VT-220 had protection diodes cludged at the factory around and above the transceiver chips. Does anyone the reason for the high mortally rate for these transceiver chips or were they just badly designed ? Paul Keinanen ////////////////////////////////////////////////////////////////////////////// Path: utkcs2!stc06.ctd.ornl.gov!cs.utk.edu!gatech!news.mathworks.com!mvb.saic.com!info-vax From: BENCHABANE@IST.CERIST.DZ Newsgroups: comp.os.vms Subject: Re: LK201 keyboard failures Message-ID: <01IGLS2DOW5U002207@IST.CERIST.DZ> Date: Mon, 17 Mar 1997 09:44:27 +0000 (GMT) Organization: Info-Vax<==>Comp.Os.Vms Gateway X-Gateway-Source-Info: Mailing List Lines: 29 Hello Dennis, Inside the LK201 there is a printed circuit (field service module) : part number : 54 16941 or 54 15148. depending of the version of this module you have differents integrated circuits, resistors , capacitors etc... on the 1st part number , there are 3 IC's. on the th 2nd : 9 IC's etc... 2 of them make the communication between the KB and the logic board inside the VT: UA (or MC) 9636 for transmit UA (or MC) 9639 for receive. on this board there is a voltage reglator : MC 7805 which deliver + 5V. The flat cables (from this module to the keys map) are not easy to remove or replace...so be carefull. The failure is not necessary on the module; the failure can de caused by the keys map if one key is detecded down during the power on. I hope this helps. But I am looking for the error code displaying by the LK201 LED's..... -- Lies BENCHABANE E-mail: benchabane@ist.cerist.dz ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: stc06.ctd.ornl.gov!news.er.usgs.gov!jobone!newsxfer3.itd.umich.edu !cpk-news-hub1.bbnplanet.com!su-news-hub1.bbnplanet.com !news.bbnplanet.com!csn!nntp-xfer-1.csn.net!csn!nntp-xfer-2.csn.net !symbios.com!news Date: Mon, 14 Apr 1997 10:51:55 -0600 Organization: Symbios Logic Message-ID: <335260AB.6668@symbios.com> References: <334D08F7.705A@mail.bellsouth.net> NNTP-Posting-Host: jkrantzpc.co.symbios.com From: Joe Krantz Subject: Re: VT220 - have many giving "keyboard error code 4" - typical causes? Paul V. Kretzschmar wrote: > > Hey, > > Got a ton of used vt220's that > I have to get running again, most keyboards > giving error code 4.... suspect keyboard > membranes may be bad as they were lying on > top of one another for awhile. > > Anyone have input on this error, are keyboard > fixable, maybe open-up and clean keybd interiors?? It could be keys that are stuck down/jammed together, or bad cable/connection between the monitor and the keyboard (check *both* ends), or it could be the monitor/system end - find one 'system' that passes the test, and cycle all keyboards through that 'system'. You can try blowing the dust out of them with a high pressure air hose, or turn them upside down, and 'bang' them a bit. Also, try opening up one of the failing units and see if someone has spilled anything into it (like coffee or coke...). Joe P.S. One more thought, if you pop off any of the keys, be careful of the larger keys, some contain one or more springs that can be hard to find if you aren't expecting them. Joe ////////////////////////////////////////////////////////////////////////////// Newsgroups: vmsnet.pdp-11 Path: utkcs2!stc06.ctd.ornl.gov!news.he.net!feta.direct.ca!newsfeed.direct.ca !cpk-news-hub1.bbnplanet.com!cam-news-hub1.bbnplanet.com !news.bbnplanet.com!news-xfer.mccc.edu!mars.njcc.com!not-for-mail Message-ID: References: <199709050437.AAA07232@endor.harvard.edu> Organization: NJ Computer Connection for Astro Imaging Systems From: hjohnson@pluto.njcc.com (Herbert R Johnson) Date: Sun, 07 Sep 1997 19:21:32 -0400 Subject: Re: power supply sadness In article <199709050437.AAA07232@endor.harvard.edu>, Dan Lanciani wrote: *> *>So, an hour later I have the thing apart (hate those locktighted standoffs) *>and I've found the shorted cap (after a few wrong guesses). I replace the *>cap, put it back together, and power up. All the voltages are right. Then *>the smoke starts billowing out. Shut it off, take it all apart again, *>nothing seems burned. Power up again and the voltages are still fine. *>No more smoke. Very frustrating. I assume some other cap decided to die *>but couldn't quite maintain its short. :( It's harder to troubleshoot a *>working supply and there are a lot of caps in this box... I have similar problems with S-100 equipment from the same era. It's simple physics: tantalum-based capacitors, for example, grow "whiskers" of tantalum over time. As these get bigger, they eventually puncture the dielectric and create shorts. That's why some little capacitors "flame on" upon powerup and create smoke, flame, etc. (Really helps to drop the price during negotiations, incidently.) There are other problems with electrolytics that are due to the passage of time and heat. In the old, vacuum-tube days, it was recommended that unused equipment be powered up from a low-voltage AC source and slowly raised. Don't know how multi-voltage chips like old DRAMS would like that today. Sometimes I use a Variac to power up older equipment for initial tests. Shorts can be detected with an ohmmeter, to the extent the rest of the circuit doesn't appear as low resistance. I've been using a capacitive scale on a new DVM to find shorted and undervalued caps, with some success. THey are modestly accurate, and can measure from tens of pF's to a few hundred microfarads. Herb Johnson -- Herbert R. Johnson voice/FAX 609-771-1503 day/nite hjohnson@pluto.njcc.com Ewing, NJ (near Princeton) USA occasional amateur electronic astronomer supporter of classic computers as "Dr. S-100" and senior engineer at Astro Imaging Systems: old photons to new bits! ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair, comp.terminals, biz.marketplace.services.computers Date: Wed, 18 Feb 1998 15:32:11 -0500 From: depotdig Subject: 15 Years in WYSE Repairs! Are your Wyse terminals acting up? We can help! We've got 15 years experience repairing Wyse products. Low, flat rates. DEPOT DIGITAL SERVICES Questions? Call 813-881-9388 or Email us! ////////////////////////////////////////////////////////////////////////////// ------------------------- Message-ID: Organization: PCR Date: Fri, 03 Jul 1998 03:46:55 GMT From: BoB Newsgroups: comp.terminals Subject: wyse flyback we got all kind of wyse flyback, give ys a call, jason, 514-333-1455, pcr ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <3607F23B.F5618588@edgenet.net> Message-ID: <19980923190159.04114.00000853@ng25.aol.com> Date: 23 Sep 1998 23:01:59 GMT From: MeOzzy Subject: Re: Keyboards! I can sell used DEC keyboards. We do test them in the refurb. center and test them before we ship them. -- Richard PMM Pager +1 504/929-1864 ////////////////////////////////////////////////////////////////////////////// Date: Sun, 5 Dec 1999 15:37:03 -0000 Newsgroups: comp.terminals Message-ID: <384a8a99@news.jakinternet.co.uk> From: Gavin Atkinson Subject: Wyse WY-85 needing repair Hi, I have a Wyse WY-85 terminal which was recovered from a pile of junk. However it seems to have a power supply problem. I was wondering if anyone knew of a company in england (preferably Northern England) who repair these. Or even better, if anyone can point me to websites/locations of service manuals etc so I can repair it. (I am able to repair it if I knew what the problem was). Many web searches have turned up nothing sadly. Many thanks, Gavin. ////////////////////////////////////////////////////////////////////////////// Date: Sun, 5 Dec 1999 21:57:31 -0500 Newsgroups: comp.terminals Message-ID: <384b268a.0@news3.paonline.com> From: droid Subject: Re: Wyse WY-85 needing repair . >Or even better, if anyone can point me to websites/locations of service >manuals etc so I can repair it. (I am able to repair it if I knew what the >problem was). Many web searches have turned up nothing sadly. Gavin, Wyse was notorious for using a glue which becomes conductive over the years. it is colored yellow but becomes brown. chances are that is the problem.i use a dental pick to scrape it off the components. if you have an ohmeter, just touch a glob of glue and see if you get a reading, if so that is the problem. good luck ////////////////////////////////////////////////////////////////////////////// Date: Sun, 5 Dec 1999 22:17:03 -0500 Newsgroups: comp.terminals Message-ID: <384b2b1e.0@news3.paonline.com> From: droid Subject: Re: Wyse WY-85 needing repair oh yeah ,one more thing , any monitor that is malfunctioning is suseptible to keeping the main capacitors charged, so you might want to check them with a voltmeter first before doing the remove glue procedure... ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <65089820.0110311908.112b2cf@posting.google.com> <3BE06A10.A43A33B@rcn.com> <65089820.0111031705.42f3f66f@posting.google.com> Message-ID: Organization: Excite@Home - The Leader in Broadband http://home.com/faster Date: Sun, 04 Nov 2001 08:10:31 GMT From: mroberds@worldnet.att.net Subject: Re: Wyse 75 terminal problems Ian Primus wrote: > >The high pitched squeal remains, and seems to be coming from the >black dealy that it connected to the video tube by a fat red cable >and a suction cup. This is the flyback transformer. It converts the line voltage coming into the terminal (120v or 240v) into a very high voltage for the picture tube - on the order of 15 to 25 kilovolts. The current is low, but it's still enough to zap you if you put yourself across it. >I have been trying to identify the smell, it doesn't seem to be a >burning smell after all, it is an acrid smell, almost like the smell a >photocopier makes. Sounds like ozone. Does it smell like the electric bumper cars at an amusement park? Usually this smell comes from sparks - in your case the high voltage from the flyback transformer sparking to something else, due to a loose connection or broken insulation. >I have a knowledge of electronics, but I normally work with low >voltage circuits, computers, etc. Take a look at http://www.repairfaq.org/ and specifically the monitor repair FAQ at http://an.hitchcock.org/repairfaq/REPAIR/F_monfaq.html [2005 mirror: http://repairfaq.ece.drexel.edu/sam/monfaq.htm ] There is a section in the monitor FAQ specifically about the whining noise you have. Good luck! Matt Roberds ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <65089820.0110311908.112b2cf@posting.google.com> <3BE06A10.A43A33B@rcn.com> <65089820.0111031705.42f3f66f@posting.google.com> Message-ID: <65089820.0111041612.5a263da9@posting.google.com> Organization: http://groups.google.com/ Date: 4 Nov 2001 16:12:50 -0800 From: Ian Primus Subject: Re: Wyse 75 terminal problems Well, I used a length of rubber hose as a stethescope and determined that the soud is not coming from the flyback, but is in fact coming from what appears to be a regular transformer on the left (looking from the back) side of the board. I am assuming that this is the low voltage transformer. I tried tapping on it and some of the surrounding components with a pen barrel, and the noise went away. If I jiggle something else, it will come back, and putting the cover back on it seems to jiggle it as well, returning it to the annoying whine. Any ideas? Ian Primus ian_primus@yahoo.com ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <65089820.0110311908.112b2cf@posting.google.com> <3BE06A10.A43A33B@rcn.com> <65089820.0111031705.42f3f66f@posting.google.com> Message-ID: <9s4s3u$gbq$4@dos.canit.se> Organization: Canit Public Access, Stockholm Date: 5 Nov 2001 02:04:46 GMT From: Iggy Drougge Subject: Re: Wyse 75 terminal problems Ian Primus skrev: : : After a little bit of running, the wavyness went away... The high : pitched squeal remains, and seems to be coming from the black dealy : that it connected to the video tube by a fat red cable and a suction : cup. Whacking the table sometimes changes the pitch of the squeal. I : have been trying to identify the smell, it doesn't seem to be a : burning smell after all, it is an acrid smell, almost like the smell a : the terminal works just fine, save for the noise. It could use an : done, and I really need the terminal. I have a knowledge of : electronics, but I normally work with low voltage circuits, computers, : etc. I know very little about monitors. Fortunately, I am good with a : soldering iron, but I really don't know what I need to replace. Any : ideas? I've got an old terminal with the same problem (high pitched squeal). I've been told by people experienced with CRT repair that it's the flyback transformer which has started to decompose, resulting in certain parts vibrating at high frequencies. The flyback is the big, unshapely thing coated in resin, connected to the suction cup on the CRT. One cure which might work is to encapsulate and fixate the flyback with great amounts of glue. -- /Iggy, the irregular regular ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <65089820.0110311908.112b2cf@posting.google.com> <3BE06A10.A43A33B@rcn.com> <65089820.0111031705.42f3f66f@posting.google.com> <65089820.0111041612.5a263da9@posting.google.com> Message-ID: Organization: Excite@Home - The Leader in Broadband http://home.com/faster Date: Mon, 05 Nov 2001 06:59:49 GMT From: mroberds@worldnet.att.net Subject: Re: Wyse 75 terminal problems Ian Primus wrote: >Well, I used a length of rubber hose as a stethescope and determined >that the soud is not coming from the flyback, but is in fact coming >from what appears to be a regular transformer on the left (looking >from the back) side of the board. I am assuming that this is the low >voltage transformer. If it's a fairly good distance from the flyback, and is near where the power cord attaches to the board, then yeah, that's probably it. How is it attached to the board? Sometimes they are just held down by the solder on their leads. Sometimes there are nuts and bolts holding it to the board, and sometimes there are metal tabs on the transformer frame that go through holes in the board and are bent over. If it's just held down by the solder you can't do much about that, but you can tighten bolts and attempt to tighten bent tabs. Rivets are also used; if you can't tighten them by crimping them with pliers, try soldering the rivet in place. Do this with the terminal unplugged and use a big soldering gun, being careful of nearby components. Some transformers like this are made so that the laminations+coil just slides into a stamped sheet metal frame. You could try crimping the frame down on the laminations with a pair of pliers to tighten it up. Do this with the power off and use insulated pliers anyway. Looking at it from the side or the top, where ** is the coil and the bar in the middle is the frame: ._. --->| |<--- crimp here **| |** **| |** **| |** --->|_|<--- crimp here If it doesn't have an obvious outer frame (usually shiny) over the laminations (usually flat and dull), then don't do this. If there is enough room between the transformer and the board, you might try jamming something non-conductive (wood or plastic) in there to quiet it down. Or try a plastic self-locking cable tie (zip tie) or two around the whole transformer. If you've localized it to this transformer then you should be able to do something to it to make the noise stop. Matt Roberds ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <65089820.0110311908.112b2cf@posting.google.com> <3BE06A10.A43A33B@rcn.com> <65089820.0111031705.42f3f66f@posting.google.com> <65089820.0111041612.5a263da9@posting.google.com> Message-ID: <3BE621FC.562EAA78@rcn.com> Date: Mon, 05 Nov 2001 05:22:04 +0000 From: Jim Subject: Re: Wyse 75 terminal problems Pretty good diagnostics.. everyone is pretty much on the same page on this one. What bothers me is the wavy lines coupled with the smell of something overheating.. The power supply circuit is either a full wave or a half wave rectifier circuit. If it is a full wave you will see two distinct and separate lines of distortion slowly rolling verticle up the screen. This will distort the font. If it's a half wave circuit you will only see one line. What is happening, is that some component of the low voltage supply is failing and quite posssibly repair intself temoparily when it heats up.. Possibly the filter capacitors. That would cause a drop in the overall DC power supply output level as there would be quite a bit of AC ripple riding on top of the DC. It would also cause the power transformer to heat and the insulation of the windings to break down over time. The filter capacitors are probably electrolytic and they dry out with time. The terminal is not exactly of new manufacture. In fact, it's some years old. While it's nice in theory, The repair faq's mentioned in Mroberds response will tell you the same thing. My own experience tells me that's whats happening. Power transformers have a distinct smell to them when they get hot. You might check for residue around the base of the transformer which would indicate insulation breakdown that is leaking through the case. Capacitors don't have to look burnt or deformed in order to have failed or be in the process of failing. Most people just replace them when in doubt and not in possesion of good test equipment. ////////////////////////////////////////////////////////////////////////////// Path: utkcs2!gatech!swrinde!mips!pacbell.com!att!cbfsb!cbnewsb.cb.att.com!wa2ise From: wa2ise@cbnewsb.cb.att.com (robert.f.casey) Newsgroups: comp.terminals Subject: VT220 display repair Keywords: bad pot in sync circuit Message-ID: <1991Dec28.155531.9997@cbfsb.att.com> Date: 28 Dec 91 15:55:31 GMT Sender: news@cbfsb.att.com Organization: AT&T Bell Laboratories Lines: 16 I have a VT220 terminal that had a display problem. The image (charcters on the screen) used to wiggle side to side from time to time. Took the cover off, and found that the pot marked something like "horiz hold" seemed dirty. When I rotated it some, the wiggle problem would clear for a while. Got tired of having to do this every so often, so I replaced this pot. No more wiggles since I did this a week ago. BTW, when I got this terminal, the display was not horiz sync-ing at all. Cleared that by playing with this pot. This bad pot caused the reason why I was given this terminal in the first place. This pot is the one inside the display, on the left side, closest to the front. You have to take the back cover off to see it. It's just a cheap trimpot type. 5K ohms. 4.7K will also work. Try to measure the old pot with an ohmeter to verify this though. This may be all that's wrong with that VT220 sitting in the back room. Disclaimer: proceed at your own risk. WA2ISE ////////////////////////////////////////////////////////////////////////////// Path: utkcs2!emory!swrinde!mips!mips!decwrl!access.usask.ca!regina !mercury.cs.uregina.ca!hubich Newsgroups: comp.terminals Message-ID: <1992Feb25.162530.10716@regina.cs.uregina.ca> Sender: usenet@regina.cs.uregina.ca (Usenet Admin) Reply-To: hubich@mercury.uregina.ca (Chad D. Hubich) Distribution: comp.terminals sci.electronics Organization: University of Regina, Regina, Saskatchewan Lines: 39 Nntp-Posting-Host: mercury.cs.uregina.ca Date: 25 Feb 1992 16:25:30 GMT From: hubich@mercury.cs.uregina.ca (Chad D. Hubich) Subject: VT100 Repairs Over the years we have repaired a few DEC VT100 terminals with various problems. Typically the same failures occur repeatedly in different machines. Below is a short summary of some of the most common failures and their fixes. If anyone has any other repeair info, especially with the last problem, please post it to the net. Symptom Possible Fix ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ No HV or filament voltage check/replace F401 2A picofuse (usually caused by some other failure) No video or only vertical check/replace C441 10uF, 35V bi-polar line down center of screen (no horizontal deflection) No video, middle of screen check/replace C439 100uF, 25V compressed or warped along vertical line or screen too wide. No video check/replace CR408 1N5408 R478 hot or smoking Low HV or Jittering video check/replace flyback transformer Error '2' (NVR) at power replace E24 (logic board) ER 1400 up or when Setup is saved Bright raster along left ?????????????????????????????????????? side of screen ----------------------------------------------------------------------------- Chad D. Hubich Technician hubich@cs.uregina.ca University of Regina chubich@ureginav.BITNET Department of Computer Science ----------------------------------------------------------------------------- ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Message-ID: <3D222839.7AC34E8E@yahoo.com> Organization: Road Runner Date: Tue, 02 Jul 2002 22:25:32 GMT From: Sark Subject: VT100 help Thank you all for your help on my VT220 and the null modem cable wiring, and while I still haven't had time to take another shot at wiring a null modem cable, I do have the VT220 up and running on the Linux box and the backspace works. I hope I'm not asking too many questinons, but I recently accquired an original DEC VT100 terminal. It works, but there are a couple of annoying little problems... 1). The screen is rather distorted. Characters appear taller at the top of the screen than they do at the bottom, and the display does not extend all the way to the bottom of the tube. (stops about 1.5 inches away from where I think it should) My guess would be that it is a capacitor failing in there somewhere, but which one? I haven't gotten inside it yet (see next question) 2). I can't figure out how to get it apart! There don't appear to be any screws on the bottom, just these funny white plastic things. 3). The "Enter" key sticks. Sometimes I have to hit it several times before it will register. I assume this could be fixed by taking the key off and cleaning the contacts, but I haven't gotten around to it. 4). The "Setup" key is missing (or at least, I assume that is what it is supposed to say). I figured out how to get into the setup from Richard Shuford's site, and as there was reference to a "Setup" key, I figured that it must be the missing one... (in retrospect, I could have just pressed it to see what happened, but I thought it was a funtion key or something, and ignored it) Anyone know where I can get another key? Actually, any VT100 parts/terminals would be helpful, as I want to be able to keep a working VT100 around at all times, I just love using it) 5). The terminal's casing is REALLY yellowed. I want to clean it up, but I don't want to damage the plastic. Any suggestions? Also, not a problem, but a misconception I had, My VT100's screen is green. I was led to believe that the VT100's had black and white screens. This could have been because of a black and white photo, but I'm not sure. Did they make them in different models like they did VT220's? If so, did they make them in amber as well? Thanks in advance, any information regarding the VT100 would be much appreciated. Thanks! Ian Primus ian_primus@yahoo.com ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals References: <3D222839.7AC34E8E@yahoo.com> Message-ID: <3D22B497.3629A13C@carmen.se> Organization: Carmen Systems AB Date: Wed, 03 Jul 2002 10:23:51 +0200 From: Christian Brolin Subject: Re: VT100 help Sark wrote: > > 2). I can't figure out how to get it apart! There don't appear to be any > screws on the bottom, just these funny white plastic things. Just pull the centre of those plastic nobs out (down 1/3") with a sharp screwdriver or knife and then you can lift off the case. > 4). The "Setup" key is missing (or at least, I assume that is what it is > supposed to say). I figured out how to get into the setup from Richard > Shuford's site, and as there was reference to a "Setup" key, I figured > that it must be the missing one... (in retrospect, I could have just > pressed it to see what happened, but I thought it was a funtion key or > something, and ignored it) Anyone know where I can get another key? > Actually, any VT100 parts/terminals would be helpful, as I want to be > able to keep a working VT100 around at all times, I just love using it) I have some parts/terminals around, but I can't figure out how to configure my modem for hardware attachments. > Also, not a problem, but a misconception I had, My VT100's screen is > green. I was led to believe that the VT100's had black and white > screens. I think the black and white screens were the most common ones. /Christian ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals NNTP-Posting-Host: 65.94.149.187 NNTP-Posting-Date: Sun, 04 Jan 2004 17:57:47 EST References: <3FF3D5D7.AC1CCDD6@myownboss.com> Message-ID: <3FF89A14.C12066E1@myownboss.com> Organization: Bell Sympatico Date: Sun, 04 Jan 2004 17:56:21 -0500 From: stockwiz Subject: Re: How to reach contacts of a key on Wyse ASCII keyboard Matthias Czapla wrote: > > stockwiz wrote: > > > > This is a common problem with the Wyse KB that uses the Cherry key > > mechanism.It is best if you can replace the key. If that's not feasible > > then a temporary solution(sometims it will work for quite a while) is to > > take the keycap off and push the stem of the key down while at the same > > time squirt some contact cleaner inside the key assembly.This had work > > for me in the past. > > I'll try that. Have to get some contact cleaner first. > > > Now If I encounter the > > same problem I basically replace the key. Good luck again. > > Two problems. How do I remove the key and where can I get a replacement? > > Regards > Matthias To remove the key, you have to turn the keyboard over and unscrew the 4 screws that hold the back cover of the KB together. After taking the cover off you will see the backside of the KB assembly. (If you do not know how to desolder or solder part on a circuit board, have someone do it for you. It is just a matter of 2 solder joints for each key switch.) Once you have the 2 solder joints of the key you want to remove turn the KB over again and pop the keycap of the key off. Then use a thin slot screwdriver to lift the key off the housing of the KB assembly. (It is also a good time now to check for cold solder joints on other keys as it is a problem with the Wyse KB. It may even solve your current problem if the key you have problem with has a cold solder joint.) As for key replacement you can either order form Wyse (expensive) or get a similar replacement from your local electronic store (if they stock them). I got mine (a good supply) from a local electronic store a few year back at $1 each. But I can no longer find it anymore locally.If you have problem locating the key LMK I could sell you a few for the same price I paid for it+postage. .............................................................................. Newsgroups: comp.terminals References: <3FF3D5D7.AC1CCDD6@myownboss.com> <3FF89A14.C12066E1@myownboss.com> Message-ID: Date: Wed, 7 Jan 2004 14:18:29 +0100 From: Matthias Czapla Subject: Re: How to reach contacts of a key on Wyse ASCII keyboard stockwiz wrote: > > To remove the key you have to turn the KB over and unscrew the 4 screws that > hold the back cover of the KB together. After taking the cover off.... > It is also a good time now to check for cold solder joints on other > keys as it is a problem with the Wyse KB. It may even solve your current > problem if the key you have problem with has a cold solder joint. I checked it and the solder joints look perfectly good to me (although I'm no expert in this area). > As for key replacement you can either order form Wyse (expensive) or get a > similar replacement from your local electronic store (if they stock them). > I got mine (a good supply) from a local electronic store a few year back at > $1 each. But I can no longer find it anymore locally.If you have problem > locating the key LMK I could sell you a few for the same price I paid for > it+postage. I really appreciate your offer, thanks. I searched the two German online electronic stores I know but couldnt find these keys. So I asked Cherry for a supplier and they will send me some for free! Very nice I think :) Thank you very much for your help, stockwiz. Best Regards Matthias ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: utkcs2!darwin.sura.net!mips!think.com!ames!agate!stanford.edu!rutgers !att!cbfsb!cbnewsb.cb.att.com!wa2ise Message-ID: <1992May10.222121.20507@cbfsb.cb.att.com> Organization: AT&T Bell Labs References: <1992May6.170201.12039@phillip.edu.au> Date: 10 May 1992 22:21:21 GMT From: wa2ise@cbnewsb.cb.att.com (robert.f.casey) Subject: Re: VT220 questions In article <1992May6.170201.12039@phillip.edu.au>, t9114145@phillip.edu.au writes: > >I've just acquired a VT220, made in 1985. 'setup' says V2.00. > >How do I connect a printer to it, i.e. what are the pinouts to make a >DEC-to-25 pin serial adaptor. Also does anyone have a standard set of >pinouts for a 25-pin serial printer's 25-pin D? I'd like to know this, too (can't RTFM 'cause I don't have a manual!) >The screen is very jittery right after it gets turned on, but smooths >out once it's warmer until you can't see the jitter any more. Anyone >have any suggestions what this might mean or how it could be fixed? The >20-odd VT220's at college don't do this. My VT220 had jitter. Found, in my case, it was a dirty horizontal hold trim pot. To get to it, you have to take the back off. It's on the left side if the flat circuit board, foward (if memory serves right). I replaced it in mine (a 5K trimpot, think I got the replacement from Radio Shark). ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals Path: utkcs2!gatech!ncar!virga.rap.ucar.edu!ren Message-ID: <1992Jun5.142628.1101@ncar.ucar.edu> Keywords: Sources for replacement terminal parts Sender: news@ncar.ucar.edu (USENET Maintenance) Reply-To: ren@virga.rap.ucar.edu (Ren Tescher) Organization: Research Applications Program/NCAR, Boulder, CO Distribution: usa Date: Fri, 5 Jun 1992 14:26:28 GMT From: ren@virga.rap.ucar.edu (Ren Tescher) Subject: SUMMARY: VT-320 flyback source needed I wrote: > >Yesterday my VT-320 smoked. Opening the case I found a cracked and >melted flyback transformer. I haven't checked to see if it took the >Horizontal Output Transistor (H.O.T.) with it. Nor have I called >DEC for a part number/price. No part # is on the flyback. I have >replaced flybacks many times before (let me tell you about my RCA >television repair days!). Has anyone replaced the flyback before, >and where did you get it? The Dalbani catalog did not have a DEC >category. From: Blair Groves |Ren, you might try calling Sharon Industries in San Jose, California; |they are at (408)-456-1600... they have a lot of parts for TeleVideo |terminals mainly, and all the other popular terminal brands. They are |pretty reasonable about prices. Terry Torres can look after you there. From: ssi!cjr@uunet.UU.NET (Cris J. Rhea) Try Computer Component Source, Inc. (1-800-356-1227) A VT320 Flyback is 17.99 qty 1. [note: They were the only ones whose catalog I've received so far, and they also have a Wyse-60 flyback kit for $11.99! ren] From: George Konstantinopoulos Try CRC Components Inc. (800)822-1272 or (714)468-9711 DEC wants a $160 to replace the motherboard! (They won't sell the part). Thanks to those who replied! ren n0pvi dona nobis pacem ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.sys.dec, comp.os.vms, comp.terminals, alt.sys.pdp11 NNTP-Posting-Host: 174.44.24.192 NNTP-Posting-Date: Wed, 03 Mar 2010 18:52:03 -0600 References: <8699c9e7-8396-42eb-a7e3-54734dcfc98f@q21g2000yqm.googlegroups.com> Message-ID: Date: Wed, 03 Mar 2010 17:52:02 -0700 From: GreyCloud Subject: Re: VT420 Flyback Transformer Needed urbancamo wrote: > > Hi folks, > > Well, my VT420 let out some magic smoke the other day, and is no > longer happy. Upon visual inspection I would say the flyback > transformer is no longer alive. I don't suppose anyone has one kicking > around in their collection of parts they could let me have (or > alternatively the board in which it sits)? Would be a shame to have to > skip the whole terminal. > > Many thanks, Mark. Unfortunately, you'll need more than the flyback to fix it. You'll need a schematic to identify the parts near it as well. The capacitors and a diode usually go first and are the cause of the flyback failure. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals, comp.sys.dec Message-ID: References: Organization: VT100.net Date: Mon, 08 Sep 2003 17:31:18 +0100 From: Paul Williams Subject: Re: the joy of terminals, part 1: the VT 102 On Mon, 08 Sep 2003 10:19:12 +0000, Phillip Helbig wrote: > > I just fired up a VT 102 I have had for a few years but have never had > in use.... > > I always am wondering for each piece of hardware---especially terminals > and monitors---how much idle time is necessary before switching it off > is the better option, i.e. the gain by not having it switched on is more > than the loss caused by the stress of switching it off and on. Any idea > what that time would be for the VT 102? > > I notice that the size of the text decreases from the top of the screen > to the bottom. Is there any way to adjust this, or is it just a > symptom of age? Vertical linearity is controlled by R342 on the Video Monitor Board. VT101 Series Pocket Service Guide: http://vt100.net/docs/vt101-ps/ Be careful when prodding around near the CRT anode! - Paul .............................................................................. Newsgroups: comp.terminals, comp.sys.dec Message-ID: <7w77b.233$wu1.211@bignews4.bellsouth.net> References: Date: Mon, 8 Sep 2003 18:37:16 -0400 From: Homer Simpson Subject: Re: the joy of terminals, part 1: the VT 102 The VT320 was notorious for losing brightness over time. There is an internal adjustment, but that only gets you another few months of acceptable brightness. Replacing the CRT/Bezel assembly is the only fix (or swap it with another one). As I recall, there are also adjustments on the 102 and the 320 for both vertical and horizontal linearity. You may need a "swizzle stick" from a TV repair store (or Radio Shack) to do the horizontal adjustments (caution - don't use a metal allen wrench or you will get burnt!). To leave on or not to leave on - that is the question. It kind of depends on the frequency of use. .............................................................................. Newsgroups: comp.terminals Message-ID: References: Organization: Aracnet Date: 8 Sep 2003 23:26:12 GMT From: healyzh@aracnet.com Subject: Re: the joy of terminals, part 1: the VT 102 Jacek Ruzyczka wrote: > > I have a similar problem with my VT420 (manufactured in June 1991): > Horizontal lines often look "hanging" near the right edge of the screen, so > they ain't straight lines any more. Additionally, the characters on the > screen sometimes start pivoting a little bit --- just as is if the screen > were drunk! :-X > I suppose this is a matter of age. Besides, it could be electromagnetic > interference as I have a 17" PC screen just half a meter away from my VT. I'm kind of doubtful that the VT420 is receiving interference that is causing the problem. What I would worry about is what the VT420 might be doing to your 17" Monitor. Based on how the VT420 that's the console for a couple of my systems messes up the 21" Monitor that's *very* close to it, when I have the VT420 turned on, I tend to suspect that the VT420 lacks any kind of Magnetic shielding. I've seen what unshielded speakers can do to a computer monitor, and it isn't pretty. I'd thought they were shielded :^( Zane ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.sys.dec, comp.terminals NNTP-Posting-Host: c-24-3-109-191.hsd1.pa.comcast.net NNTP-Posting-Date: Sun, 4 Apr 2010 12:59:50 +0000 (UTC) References: <3bdfdf0e-d11a-419b-8256-f0bab22adf87@k19g2000yqn.googlegroups.com> Message-ID: <2be229e2-e677-4eb3-96f4-b8ac2a6027dc@5g2000yqj.googlegroups.com> Organization: http://groups.google.com Date: Sun, 4 Apr 2010 05:59:50 -0700 (PDT) From: jjh Subject: Re: VT320 Display Vertical Linearity Problem On Apr 3, 11:15 pm, urbancamo wrote: > > Hi, > > I've got a VT320 who's display is not linear vertically. The display > is half the size of normal and character size shrinks rapidly at the > bottom of the display to a bright bar. I've tried adjusting the > vertical linearity and size potentiometers but cannot get a good > display. > > I'm reading general monitor service guides, but was wondering if > anyone had come across this issue before and therefore might have a > better idea of which components to look at first. I don't suppose > there is a schematic for VT320s kicking about anywhere (I've had no > luck with google). > > Thanks for the help, Mark I would check the power supply voltages, especially in the vertical section. If I understand your description, it sounds like there is not enough vertical deflection on the CRT, which suggests a power supply. If the voltages are within 5% for the stated value on the test points, you will need to scope the linear defection ckt. I'd start at the CRT and work backwards. Given the age of the unit, a capacitor is the most likely faulty component, but regulator transistors are also a good bet. Good luck John . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Newsgroups: comp.sys.dec, comp.terminals NNTP-Posting-Host: cpc1-harb7-0-0-cust763.perr.cable.virginmedia.com [92.232.150.252] NNTP-Posting-Date: Sun, 04 Apr 2010 07:08:15 UTC References: <3bdfdf0e-d11a-419b-8256-f0bab22adf87@k19g2000yqn.googlegroups.com> Message-ID: Organization: virginmedia.com Date: Sun, 4 Apr 2010 07:34:24 +0100 From: Mark Hobley Subject: Re: VT320 Display Vertical Linearity Problem urbancamo wrote: > > I'm reading general monitor service guides, but was wondering if > anyone had come across this issue before and therefore might have a > better idea of which components to look at first. It's probably a capacitor. Drop a silly scope on the various oscillator outputs and check the frequencies and output voltages to those in your service guide. (There might be variation, but have a look--if the outputs look normal, are they regular? does the output level and waveform look something like your guide tells you?) If these seem OK, then you probably need the service manual for the particular monitor. If not, what you can do is from the manual determine which oscillator is causing the problem. If nothing appears to be at fault, then the problem might be in the high tension drivers. I hate working with those, so I would probably just dump the monitor if this is the case. You could discharge the capacitors and continue to diagnose, if you wanted to though :P A visual check is a good place to start. Do the capacitors look ok? Mark. -- Mark Hobley Linux User: #370818 http://markhobley.yi.org/ ////////////////////////////////////////////////////////////////////////////// Date: 20 Apr 2002 23:32:57 -0400 Organization: University of Pennsylvania Newsgroups: sci.electronics.repair, comp.terminals Message-ID: <6wlmbh4tg6.fsf@saul.cis.upenn.edu> References: <3CC22D19.F5B94970@yahoo.com> From: Sam Goldwasser Subject: Re: Televideo 950 problems Sark writes: > > I recently accquired an old Televideo 950 terminal. It was rather dirty, > but it seemed to work (I turned it on for a minute, and it worked fine). > I got it home, cleaned it up and plugged it in. It turned on fine, but > then it started to make a high pitched whine, and there was nothing on > the screen. Then the whine went away and the picture showed up. It was > stable for a few seconds, then it started to get out of whack and the > whine appeared again. It was odd looking, it was as if all the > horizontal lines that made up the image were sliding around left and > right, and not lining up. The whine increased and the picture got worse, > then the picture disappeared again and the whine was in full force. The > picture then came back and the whine went away, and I shut off the > terminal to prevent doing more damage to it. My best guess would be a > failing capacitor in the horizontal drive circuit, but I don't know > these terminals or monitors that well. I have done some simple repairs > on this sort of thing, resoldering flakey connections and replacing > blown caps, and I understand the voltages involved. What capacitor/part > could be causing this? Is this a common problem? I really want to get > this thing going again, it has such a nice retro look to it :). This is a real long shot since my Televideo knowledge is packed away along with fresh dinosaur eggs, but there was a non-polarized electrolytic capacitor in the Horizontal-deflection circuit that went bad in those things. However, I don't recall if it would have had anything to do with your symptoms. ;) In any case, if you have an ESR meter, check all the electrolytics! --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html ////////////////////////////////////////////////////////////////////////////// Date: Sun, 21 Apr 2002 01:19:08 -0400 Organization: WWW.US.INTER.NET Newsgroups: sci.electronics.repair, comp.terminals Message-ID: References: <3CC22D19.F5B94970@yahoo.com> From: Jerry G. Subject: Re: Televideo 950 problems Check the non-polarized caps in the horizontal-deflection output section. This goes too far back for me! Also the caps in the scan circuits, and especially in the power supply can be troublesome in these. If you replace the non polar caps in the scan section, you require the proper rated ones. Don't throw just anything in to the monitor. -- Greetings, Jerry Greenberg GLG Technologies GLG ====================================================== WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm Instruments http://www.zoom-one.com/glgtech.htm ====================================================== ////////////////////////////////////////////////////////////////////////////// Newsgroups: sci.electronics.repair, comp.terminals References: <3CC22D19.F5B94970@yahoo.com> Message-ID: Date: Tue, 23 Apr 2002 10:58:53 -0500 From: applianceguy Subject: Re: Televideo 950 problems I attempt repairs to TV-955 terminals from time to time. Most of the problems I see are in the power supply. I have a couple that need capacitors replaced. I kinda shotgun them. I replace most if not all of the electrolytics, especially the non-polar guys. I have been putting cheap AT power supplies in these instead of repairing the factory one. After removing from the case, they usually fit right in, maybe with a little bending of heat sinks. If you're doing a retro-refurb, a kludge PS might not be kosher, tho... Paul ////////////////////////////////////////////////////////////////////////////// \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Procedures to modify a Televideo terminal for composite video output. Materials needed 1. one bnc connector 2. one 2N4400 transistor 3. one 100-ohm resistor 4. some small gauge wire 5. solder NOTE: all these materials are available from a local electronics store Tools needed 1. soldering iron 2. wire cutters/stripers 3. hand drill 4. 3/8 inch drill bit Modification instructions 1. Drill a hole in the plastic connector mounting plate of the logic board and mechanically install the bnc connector next the the keyboard cable connector. ( see diagram 1 ) 2. Locate P2 (plug 2) solder a wire from the outside connection of the bnc connector (ground) to pin 3 of p2 on the solder side of the board. Feed the wire through the hole in the board half way between the two points. 3. Solder the base of the the 2N4400 ( the base is the center lead and is marker b) to the connection for pin 6 of P2. Note: there is no pins connected to pin 6 of P2. 4. Solder the collector of the 2N4400 to the +5 volt etch next to pin 6 of P2. The etch also connects to pin 14 of ic # A39. 5. Solder on side of the 100 ohm resister to the emitter of 2N4400. 6. Solder a wire from the - lead of C1 on the component side. Connect the wire to the other side of the 100 ohm resister. 7. Solder a wire from the center connection of the bnc connector to emitter of the 2N4400a. 8. Cut the etch between option E1 and E2. (located next to P2) 9. Connect E3 and E4 Diagram 1 ------------------------------------------------------------------------ | | | | | O ----- --------------- -------------- | | O O |kbd| | printer | | rs232 | | | O ----- --------------- -------------- | | ^ | | | | | bnc connector | ------------------------------------------------------------------------ ////////////////////////////////////////////////////////////////////////////// \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Newsgroups: comp.terminals References: <3E28B332.F76E0F6@ev1.net> Message-ID: <3e2a40c0$0$79564$7f8943f3@newsreader.visi.com> Organization: VISI.com Date: 19 Jan 2003 06:08:00 GMT From: Seebs Subject: Re: Wyse-60 Information Sought In article <3E28B332.F76E0F6@ev1.net>, Charles Richmond wrote: > > A friend has a Wyse-60 terminal, and the keyboard is locked up. > He can *not* get the keyboard to communicate with the terminal. > Is there a standard way to reset without using the keyboard??? > How can he fix this??? Well, just for what it's worth, I had this problem with a WY-160, and shaking the terminal fixed it. It seems to come and go if the terminal is moved. -s -- Copyright 2002, all wrongs reversed. Peter Seebach / seebs@plethora.net $ chmod a+x /bin/laden Please do not feed or harbor the terrorists. C/Unix wizard, Pro-commerce radical, Spam fighter. Boycott Spamazon! Consulting, computers, web hosting, and shell access: http://www.plethora.net/ ////////////////////////////////////////////////////////////////////////////// http://www.wyse.com/service/support/kbase/wits/80521.txt TITLE: Miswired CRT connector DATE: 8/6/91 PRODUCT: Wyse WY85 WY99GT WY50 THE ISSUE: The Monitor Power Supply board I just installed fails. OVERVIEW: Improper marking (silk screen) for position of the "Blk" and "Brn" CRT connector wires on the Monitor Power Supply PCB. RESOLUTION: Desolder the connector wires from the PCBD. Change positions of the Brown, and Black wires...re-label the PCBD properly. ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals NNTP-Posting-Host: 151.38.235.63 NNTP-Posting-Date: Sat, 03 Jan 2004 14:30:14 MET Message-ID: Organization: [Infostrada] Date: Sat, 03 Jan 2004 13:30:14 GMT From: leonardo cerliani Subject: Wyse Kb, some keys don't work hello everyone, I recovered in my university a Wyse terminal WY-55ES and a Wyse keyboard model 901866-05 that were going to be destroyed. They weren't close to each other where I found them, and that's my first (long wished) serial terminal. I opened the keyboard to clean the internals, and noticed that some lines on the three plastic sheets are darkened. I switched on the terminal and the most of the keys work, but there are some keys (many, and not always contiguous) that doesn't. As I'm unexperienced, I'd like you to advise me about what product could I use to clean the lines. The main reason why I thought to write you is because I also guessed of the case that this keyboard could not be appropriate for that terminal. Could you tell me something about this? Thank you very much leonardo cerliani .............................................................................. Newsgroups: comp.terminals NNTP-Posting-Host: 151.37.172.132 NNTP-Posting-Date: Mon, 05 Jan 2004 00:35:15 MET References: Message-ID: Date: Sun, 04 Jan 2004 23:35:15 GMT From: leonardo cerliani Subject: Re: Wyse Kb, some keys don't work > There is lots of information about > what keyboard works with what terminal > at the Wyse website (www.wyse.com) under > the support section. thank you very much, I didn't noticed this page at first http://www.wyse.com/products/gpt/msrp.htm at least, now I know I have a hardware failure... best regards, leonardo cerliani ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.sys.sgi.admin NNTP-Posting-Host: cpc4-cmbg8-5-0-cust114.cmbg.cable.ntl.com NNTP-Posting-Date: Tue, 25 Jan 2005 09:42:21 GMT References: <1106410343.908492.80730@f14g2000cwb.googlegroups.com> Message-ID: <1woJd.145$tF6.29@newsfe6-gui.ntli.net> Date: Tue, 25 Jan 2005 09:42:21 GMT From: Tristram Scott Subject: Re: SGI Octane power issues LindseyWetteland@gmail.com wrote: [snip] > > When I first got the Octane (a week or so ago) it powered on and > functioned fine. Suddenly it started turning off on its own > (it behaved as if someone yanked the power cord - no nice shutdown > messages in Irix, etc). Now it rarely turns on. > > SOMETIMES, (talking like once in 200 times or so) it will power on, > but rarely stays on more than four to five minutes. There does not > appear to be any rhyme or reason as to why it turns on sometimes for > a little bit. > [snip] Sounds to me like classic symptoms of worn out electrolytic capacitors in the power supply. If you have some spare time, and feel confident working with a soldering iron, you could try and replace all the electrolytics on the high voltage board. They are very cheap, and readily available. Tony Mantler has instructions for doing this for an Indigo2. http://www.apia.dhs.org/i2ps/ The concept should be the same for the Octane. You will find the Octane power supply is (slightly) easier to dismantle than that of the Indigo2. Do remember, though, that there are lethal voltages inside the power supply, even when it is switched off. If you don't know what you are doing, leave it alone and buy another. -- Dr Tristram J. Scott Energy Consultant ////////////////////////////////////////////////////////////////////////////// Newsgroups: comp.terminals NNTP-Posting-Host: c-76-106-151-252.hsd1.fl.comcast.net NNTP-Posting-Date: Thu, 24 Jul 2008 21:58:51 +0000 (UTC) References: Message-ID: <8a029197-dd82-4b32-ad72-b3df2282dbed@u6g2000prc.googlegroups.com> Date: Thu, 24 Jul 2008 14:58:51 -0700 (PDT) From: ChucksterInJax Subject: Re: Looking for schematic for a Zenith Z-29 Terminal On Jul 16, 7:12 pm, ChucksterInJax wrote: > > Last month I won a Zenith Z-29 terminal off of eBay. Received it > without damage, but, when I powered it up, a puff of smoke came out > of the top vent. Looks like a resistor has fried and I can't tell > what the values were. > > I am now looking for a schematic or service manual for the Z-29 > terminal. Does anybody have one or know where I can obtain one? I believe I found the problem without the schematic. The charred component was not a resistor, but a solid tantalum capacitor between the output of a 7805 5V regulator and ground. The datasheets for the 7805 have a diagram with a 0.33 uF tantalum on the input and a 0.1 uF on the output. Should be an easy fix. //////////////////////////////////////////////////////////////////////////////