aaron@proxftl.UUCP (Aaron Zimmerman) (08/17/88)
My 3b1's monitor (you know, that ugly GreenScreen...) has a sore case of the
bounceys. Sometimes it will decide to sort of vibrate up and down. That is,
the image shifts on the screen, kind of like there was a problem with the
vertical hold or something. The image will oscillate briskly with a maximum
amplitude of about a half an inch. Some days the image is perfectly still, but
others it's so jumpy that it's nauseating to read the text. Sometimes it
varies within a day, but for the most part it seems to make the decision on a
daily basis. I have a surge protector (though admittedly not a great one), but
surges seem an unlikely cause. I have to do something about this before I lose
my lunch on the keyboard one day.
Any suggestions would be most welcome. Also, is it possible to simply
*replace* the monitor? I would really prefer amber, anyway. Also, monochrome
monitors are so cheap, I ought to be able to just put a new one on for maybe
$75, which would probably be cheaper than the repairs... unless there's some-
thing simple wrong... or if the problem isn't in the screen, but in the video
chip or the CPU clock or something...
Help appreciated.
--
--
__ | Aaron | Proximity Technology | #include <disclaimer.h> |
| Charles | 3511 N-E 22nd Ave. | #include <cute_quote.h> |
__ | Zimmerman | Fort Ladeda, Fla | cat flames > /dev/null |jbm@uncle.UUCP (John B. Milton) (08/18/88)
In article <593@proxftl.UUCP> aaron@proxftl.UUCP (Aaron Zimmerman) writes: >My 3b1's monitor (you know, that ugly GreenScreen...) has a sore case of the >bounceys... I had this problem with my UNIXpc while it was still under service. A monitor change fixed the problem. To avoid that, you should first wiggle the video connector where it connects to the motherboard. If you can safely set all this up while the machine is running screen diagnostics, that would be better. If it is a loose or broken cable, you should be able to wiggle the cable until the screen really flips out and find out for sure. John -- John Bly Milton IV, jbm@uncle.UUCP, n8emr!uncle!jbm@osu-cis.cis.ohio-state.edu home: (614) 294-4823, work: (614) 459-7641; CP/M to MP/M, MS-DOS to OS/2
gil@limbic.UUCP (Gil Kloepfer Jr.) (08/19/88)
In article <593@proxftl.UUCP> aaron@proxftl.UUCP (Aaron Zimmerman) writes: |>My 3b1's monitor (you know, that ugly GreenScreen...) has a sore case of the |>bounceys. Sometimes it will decide to sort of vibrate up and down. This happened to me with a DEC VT220 Video Terminal several times. What happens is that (for some reason) the horizontal hold potientiometer inside the unit got flaky from being in the same position for a long period of time (add humidity and temperature variations). A really silly fix that worked was to shut the unit off and to work the pot back and fourth a couple of times with a screwdriver, putting the control back to its original position when finished. After performing this feat, you should readjust the pot (with the power on :-{) so that the screen is pleasing to the eye and doesn't produce any annoying high-pitched squeeks. I'm going to cross-post this one to sci.electronics to see if someone in electronic-land has a more permanent solution. +------------------------------------+----------------------------------------+ | Gil Kloepfer, Jr. | Net-Address: | | ICUS Software Systems | {boulder,talcott}!icus!limbic!gil | | P.O. Box 1 | Voice-net: (516) 968-6860 | | Islip Terrace, New York 11752 | Othernet: gil@limbic.UUCP | +------------------------------------+----------------------------------------+
darren@bacchus.UUCP (Darren Friedlein) (08/19/88)
In article <593@proxftl.UUCP> aaron@proxftl.UUCP (Aaron Zimmerman) writes: >My 3b1's monitor (you know, that ugly GreenScreen...) has a sore case of the >bounceys. Sometimes it will decide to sort of vibrate up and down. That is, I'm posting this because it may be of public interest - I had my screen replaced for this while it was under warranty, but the service man showed me how to fix the problem in the future: There are three pot-switches on the monitor board that are accessible by taking the cover off the screen. They are, well, cheap, and oxide builds up on the plates and causes the "bounceys". The solution is to rotate the pots back and forth a few times until the oxide is removed. If it gets too bad (mine are getting to that point) go to Radio Shack and get some more pots (or are they trimmers? I never know the difference...) and replace the existing ones. I think the crucial one is the closest to the speaker. Watch the one in the middle, though -- if the screwdriver you're using touches the pot and the chasis at the same time, the system will short and re-boot (neat, huh :-). >Any suggestions would be most welcome. Also, is it possible to simply >*replace* the monitor? I would really prefer amber, anyway. Also, monochrome >monitors are so cheap, I ought to be able to just put a new one on for maybe >$75, which would probably be cheaper than the repairs... unless there's some- >thing simple wrong... or if the problem isn't in the screen, but in the video >chip or the CPU clock or something... >__ | Aaron | Proximity Technology | #include <disclaimer.h> | > | Charles | 3511 N-E 22nd Ave. | #include <cute_quote.h> | >__ | Zimmerman | Fort Ladeda, Fla | cat flames > /dev/null | I know the monitor can be replaced, but since it's from AT&T, I don't think it will come cheap. I had a broken "u" key on my keyboard and AT&T wanted $179 to swap for a keyboard with a working "u" key. Well, I have a working "u" key now, but I couldn't see giving AT&T $179 for it, so I have no "Input Mode" key! No big sacrifice... Hope this helps! -darren ____ / \ | Rt 4, Box 416, Durham, NC 27703 _____|_____ Darren G. Friedlein data (bacchus) : 919/596-7746 / | \ voice : 919/596-9492 ( | ) \____/ __/ {mcnc|icus|ditka|ethos|gladys|bakerst}!bacchus!darren
gbh@juniper.uucp (Geoffrey B Hoese) (08/21/88)
>My 3b1's monitor (you know, that ugly GreenScreen...) has a sore case of the >bounceys. Sometimes it will decide to sort of vibrate up and down. I just moved into a new house, and now my screen has the bouncies too. But, it seems to only be happening in the afternoon - I put a voltmeter on the AC, and it seems low - i caught it down around 103 at the lowest, with moderate screen bouncing. I imagine the voltage is jumping up and down around there, with all the air conditioners running this time of year. The best cure for this would be a UPS, but as I can't really afford one right now, so i'm looking out for a good deal on a constant voltage transformer. Mind you, a surge protector won't help as this is the opposite problem - drops in voltage rather than rises. Something else to watch for, anyway.
hoffman@pitt.UUCP (Bob Hoffman) (08/25/88)
In article <593@proxftl.UUCP> aaron@proxftl.UUCP (Aaron Zimmerman) writes: >My 3b1's monitor (you know, that ugly GreenScreen...) has a sore case of the >bounceys. Sometimes it will decide to sort of vibrate up and down. One possible cause may be similar to that which afflicts many of our Zenith and DEC CRTs: bad solder connections. The symptoms are that the display will begin to vibrate or fold over itself. If left alone, the condition worsens until you have a single vertical or horizontal line, or no screen image at all. What is happening is that the solder holding a joint cracks, creating a high-resistance connection. Heat is generated by this resistance, causing the crack to widen. Eventually, the connection begins to arc, causing even more damage. Look at the solder side of the PC board which contains the high-voltage sweep components. The problem seems to affect the larger components on the board, particularly connectors, coils, and transformers. The bad connections look like a dark ring around the component pin. Also note any discolored areas of the PC board. These indicate excess heat in that area. It's not a bad idea to take a soldering iron and some good solder and re-flow the joint at each of the pins of those components. I have repaired many "dead" CRTs this way and have not had to replace any components. Simply re-flowing the solder connections fixed them. ---Bob. -- Bob Hoffman, N3CVL {allegra, bellcore, cadre, idis, psuvax1}!pitt!hoffman Pitt Computer Science hoffman@vax.cs.pittsburgh.edu
thad@cup.portal.com (08/28/88)
Seeing your mention about the 3B1 keyboard ($$$) just reminded me: CSS (Computer Surplus Store; on Sycamore Drive in Milpitas, CA; 408/280-7814) has some 20 (twenty) pallets FULL of brand-new but cosmetic-faulted 3B1 keyboards for $20 (twenty US$) each. The difference between the 7300 and 3B1 keyboard seems to be solely the presence of the writeable strip area above the function keys (on the 3B1 keyboard). For $20, I purchased one as a spare (and it works perfectly; just a small scratch on the side). NOTE: some of the keyboards had damaged keytops, but from some over 200 to pick from, "good" keyboards can be found. The "spare" I purchased had the date code 8639 (which was more recent than the one that accompanied my 3B1) but does NOT have the bar code strip on the underside; big deal! Hope this helps.
ebh@argon.UUCP (Ed Horch) (08/30/88)
In article <8513@cup.portal.com> thad@cup.portal.com writes: >Seeing your mention about the 3B1 keyboard ($$$) just reminded me: CSS >(Computer Surplus Store; on Sycamore Drive in Milpitas, CA; 408/280-7814) >has some 20 (twenty) pallets FULL of brand-new but cosmetic-faulted 3B1 >keyboards for $20 (twenty US$) each. A couple corrections: First, the number is really (408)434-0168. The number above has been disconnected. Second, they charged me $25.00, saying that the $20.00 price was for ten or more. They made no mention, however, of an additional shipping charge from CA to NJ. If there is anything else of note once the unit arrives, I'll post it. Thanks for the pointer... -Ed