RICK@QUCDNAST.BITNET (08/31/89)
The following (slightly editted) was sent to me by a local friend of mine. It seems to have stumped the service type at the local dealer. If anyone has an inspired suggestion to make, his address is nosworth@qucdn.bitnet or nosworth@queensu.ca ---------------------------------------------------------------------- 1. about a year or so ago, i noticed that my screen would "jump" periodically -- it would suddenly shift up or down for a brief moment. i thought this was due to statitic building up on the monitor-screen, because i had recently attached a plastic "flicker-reducer" to it (the static seemed high). i bought some anti-static spray, but it didn't seem to do much good. 2. about four months ago, a new problem occurred wwith my display. fairly often, a rastor-line would "spark" accompanied by an audible "pop". this was getting very annoying (made watching the screen for long periods of time quite unpleasant). still, i assumed the problem was with my monitor (and it was getting worse). 3. in the first week of august, the thing totally died on me. on a cold boot, the kickstart screen (i have a 500, btw) would either not appear (with the internal drive trying in vain to access the startup disk), or it would be a complete mess (parts of the 'hand n'disk' shifted all over the place, colours haywire, etc). i took it in for servicing, was told my denise chip was bad, and replaced it for $100 (ouch!). when i brought it home, it was working better than ever: the screen didn't jump and the scan-lines didn't spark, so i assumed that these had been symptoms of a dying denise. 4. well, that didn't last for long...the jumps and sparks were soon back to haunt me. then, about a week and a half ago, something else happened. i started up vt100 (after having used it an hour earlier without event), and found that it wouldn't work. neither would my other term programs (and i tried a cold-boot, starting with a different workbench disk, backups of the term programs, everything!). the script file would cause the terminal to dial out, but nothing would appear on the screen (even the phone number which is usually displayed). the lights on the modem indicated that it was receiving data from the mainframe (or bbs) and that it was trying to send this to the amiga. the weird thing is that typed-in characters wouldn't show up on the screen when the terms were running so i couldn't try the at commands. my feeling is that the modem is fine, but i haven't been able to check on someone else's system yet. the service tech checked the two control chips, and they seem to be okay. he seems to think that it has something to do with the serial port control chip (paula?), but can't figure out why it's all going 'boom' at the same time. 5. and during the past week, a few other weird things have happened. a few times, when i tried to warm/cold boot off sonix, the screen display would be unbearably slow (the pointer would be seconds behind the mouse, etc) and the program wouldn't load. then yesterday, i was working with microfiche and wordperfect when i ran low on ram. i saved my work to disk after which the display started to degrade and got worse as i moved the mouse. fine, i thought, my chip ram must have been stomped. however, a cold-boot yielded the familiar messed-up kickstart requester again (sometimes it didn't even get that far, so i'd tap the machine to get it 'moving'). i left the machine off for an hour, and when i returned, it could boot again (though the display and serial/modem problems are still there). it was been ok since then, but i doubt this will last for long. so there it is. any idea what's going on? i have had an isobar surge-protector installed for over a year now, so the machine should be getting a pretty "clean" current. why are all these problems happening in quick succession? what is the common denominator? or is it just incredibly bad luck? ------------------------------------------------------------------- that's the story. thanks in advance. "Are you police officers?" "No, ma'am. We're musicians."
galvey@sts.sts.UUCP (09/01/89)
Rick, I have had the same "jump" occur on my system for some time now. I also have a friend with a 2000 (and a 1084 monitor) that has similar things happen. He has informed me that, after talking to a "Amiga Service Guru" at the local dealer, the "jump" & "POP" you experienced was propably caused by HI-VOLTAGE DISCHARGE in your monitor (1084?). It was explained that the hi voltage line going to the CRT (picture tube) runs very close to some other metal components inside the monitor. I have not taken my monitor apart yet to check this out, but having some previous experience working with Television Repair, I can understand why the screen jumps & you hear a "POP". This all happens when too much static builds up INSIDE THE MONITOR between the hi voltage line (anode, wire, etc) and some other metal (usually the chassis) surface. Since color monitors use hi voltage anywhere between 20 to 30 THOUSAND VOLTS, you will HEAR when a discharge takes place! I also heard that, in some cases, this spark can get back TO THE COMPUTER and cause all kinds of NASTIES!!! (such as the blown chips your friend experienced). It is well known in the electronics industry that ESD (Electro Static Discharge) of just a FEW thousand volts can cause component failures or DEGRADING of components, which may be the cause of the continued problems with the computer. The service guru suggested getting inside the monitor and use ELECTRICAL TAPE to wrap around the hi voltage line. When I was still working in TV repair, we used this trick all the time when hi voltage lines would get bent and get close to the chassis. One note: the tape should say something on it's label about insulation value (1kVolts per layer ?). I would also suggest that the hi voltage cable be moved as far away from all metal (including circuits) inside the monitor. CAUTION: CRTs can hold a charge for quit a while (they are BIG capacitors) so if you are not experienced with this type of thing, take it into the shop and have the service tech do it for you. I hope this helps you guys out. Send me something back to let me know what happens, maybe I will finally tear my monitor appart and do it myself! Later, Greg A.
jdm@gryphon.COM (John Mesiavech) (09/01/89)
In article <8908311544.AA28591@jade.berkeley.edu> RICK@QUCDNAST.BITNET writes: > >The following (slightly editted) was sent to me by a local friend of >mine. It seems to have stumped the service type at the local dealer. If >anyone has an inspired suggestion to make, his address is >nosworth@qucdn.bitnet >or >nosworth@queensu.ca >---------------------------------------------------------------------- {long description of bad monitor symptoms deleted for brevity} Sir; Tell your friend that his problem is NOT in his Amiga. Repeating, NOT in the Amiga. Those symptoms he had when the problems first started are diagnostic of a bad main controller board in the MONITOR. Most likely, when the problems caused his system to die, a transistor in the monitor's controller board blew and took the Denise with it, by backlashing through the monitor cable. Th secondary problems he had after getting the Denise repaired (and yes, that dealer WAY overcharged him....Denise chips are $65 from CBM, quantity one, unless CBM changed price again.) Again, the secondary problems sound like something from the monitor putting tolerable-but-just-barely signals into the video port. It almost sounds as if something enabled XCLOCKEN...but the 1080 monitor cable doesn't have that particular pin wired. Something in the connector, maybe? I would advise your friend to check his system with another monitor and cable. It may solve his probblems (or ast least locate 'em) John -- 0-=-=-=-=-=-=-=-=-> All disclaimers apply; I didn't write this <-=-=-=-=-=-0 | ----------------------|------------------- | | "I want a New Duck | John Mesiavech | | One that won't try to bite | net.soldier.of.fortune | | One that won't chew a hole in my socks | {backbone}!gryphon!jdm | | One that won't Quack all night" | Go Purdue! (by req) | | Weird Al Yankovic, "I Want a New Duck" | | 0-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-0