cb29+@andrew.cmu.edu (Chad Kavanaugh Bisk) (06/25/89)
Fellow Amiga Users, I recently ran into a problem which I am hoping has a very simple solution. My Amiga 500 has started to act very weird and is becoming unusable, and I am hoping that someone can tell me why. First off, my current configuration is: Amiga 500 with rev 5 motherboard (Serial Number ~5000) Amiga 1080 color monitor Supra 501 memory expander and clock Supra external SCSI interface w/ autoboot ROMs Supra 45 Megabyte hard disk (Miniscribe disk and controller) Kickstart 1.3 in ROM AmigaDOS 1.3 I recently bought the hard drive, controller, 1.3 ROMs, and extra memory from Lightspeed Distribution and installed everything over the weekend. Installing the ROMs was the hardest part, requiring me to open the plastic case, remove the keyboard and the metal RF shielding, pull the old ROM and put in the new, and put it all back together. The hard drive was pre-formatted and autobooted the first time I turned it on. I was having a ball that night setting up my personal directory tree. For one day everything worked fine. The next day I had been using the A500 fine in the morning. I came back in the afternoon and the freakiness started. Everything autobooted fine and the workbench came up. Upon looking closely, I noticed that there was some extra garbage on the screen that was shadowing the disk icons. Some experimentation revealed that any vertical line and some other lines had a duplicate line drawn to one side or the other (it varied) at a varying distance. I broke the system down, removing the 501 card and the hard drive and interface. The problem was still there. Now I noticed that the "Insert Workbench" screen was totally screwed. About every inch across the screen, horizontally, there was a vertical line from top to bottom and the hand/disk icon had several shadows. These were not just screen shadow images, but were actually written in to graphics memory. The flood fill blue of the disk picture was restricted to the left tenth of the disk icon since it was blocked by one of the vertical lines. This resulted in a very scary looking boot screen (almost all black and white). However, the Amiga still booted normally from either floppy or hard drive. I even played Hex to sooth my nerves for a while. I love the music that it plays. I was listening to the intro music when the second weird thing started. The sound cut down to about 1/3 the normal volume. Further experimentation with other sound programs yielded a very reduced volume and occasional static bursts. I began to suspect a short. I opened up the Amiga and blew it out. I checked all the free wiring (capacitor and transistor leads) and the internal and side expansion connectors. Nothing obvious was found. I then powered up with the cover and shielding off and felt around for overheating chips or components. No luck. I put it back together and cursed Commodore hardware quality for a while. Then I left to ask for help from my fellow NetLanders to see if there was an obvious solution that I might be missing. My only recourse is to go to a local Authorized Commodore Repair place and pay some hefty repair bills that I'd rather not have to pay. -- Chad Bisk -- cb29@andrew.cmu.edu
cb29+@andrew.cmu.edu (Chad Kavanaugh Bisk) (06/30/89)
I've had many replies to my request for help on my hardware problem. Thanks to all those who took time to help me out. It turns out that I have two problems, not one. The cause of the graphics problems is still undetermined (although its not the 1.3 ROM as I replaced that with original 1.2 ROM and got the exact same effects; I think the blitter chip must have gone sour somehow). The cause of the sound problem turned out to be a loose power connector on the system board (the black socket where the power cable enters the A500). If I press down slightly on the power cord, the sound returns to normal. I also found that this clears up a problem I've been having with the internal floppy where sometimes it won't do anything (any disk attempted disk access causes the light to light, but no drive activity other than a near silent hum from the drive motor like it's stuck or something) until I physically jar the machine. I'll bet its the ground connection which is loose since it only seems to effect this and sound quality and static over the sound lines. At this point I'm thinking I had probably just better cut my losses and take it in to a local dealer before I break something else trying to fix it. Of course, maybe I'll play with it just a little bit more first ;-). Thanks again for all the help. -- Chad Bisk -- cb29@andrew.cmu.edu
lphillips@lpami.wimsey.bc.ca (Larry Phillips) (12/29/89)
In <7057@nigel.udel.EDU>, kes%saturn.ACC.COM@salt.acc.com (Kevin Stocksdale) writes: >I have a stock A500 (with an 2002 monitor bought Nov. 1987). >Every couple of months a problem arises which can be fixed by >re-seating various chips. > > Does anyone have any suggestions as to which chip may need >replacing? You might try getting some contact cleaner (I use a brand called 'Gold-Guard'). You remove the chip, spray a little on the socket contacts, and replace the chip. While you have the chip out, take a close look at the socket itself to make sure you don't have any crud in it, and that there are no 'compressed' contacts. If you find compressed contacts, the best bet is to replace the socket, either yourself, if you are up to it in skill level, or by a service tech. Next time this happens, try reseating only one chip at a time to see if you can narrow it down. If the contact cleaner does not do the job, it might require a chip replacement. -larry -- " All I ask of my body is that it carry around my head." - Thomas Alva Edison - +-----------------------------------------------------------------------+ | // Larry Phillips | | \X/ lphillips@lpami.wimsey.bc.ca -or- uunet!van-bc!lpami!lphillips | | COMPUSERVE: 76703,4322 -or- 76703.4322@compuserve.com | +-----------------------------------------------------------------------+
kes%saturn.ACC.COM@salt.acc.com (Kevin Stocksdale) (12/29/89)
I have a stock A500 (with an 2002 monitor bought Nov. 1987). Every couple of months a problem arises which can be fixed by re-seating various chips. When I turn the power on I hear the floppy drive click every couple seconds (to determine if a disk is present). The screen which prompts the user to insert the disk a.) does not appear. b.) takes a long time to appear. c.) sometimes appears with corrupted color and vertical lines. When the screen does not appear the machine fails to recognize when I insert a disk. And on occasion the red power LED will flash 11 times then it seems that the CPU gets reset and the process repeats itself (no disk click when this happens). Because of the frequency of occurence it would not be economical to send it out for repair. Besides, I can resolve the problem by pressing on a few chips. Does the 11 flashes of the power LED signify something (diagnostic code)? Does anyone have any suggestions as to which chip may need replacing? ================================================================ Kevin Stocksdale Advanced Computer Communications kes@saturn.acc.com 10220 Old Columbia Rd. 301-290-8100 Columbia Md. 21046 ================================================================
FelineGrace@cup.portal.com (Dana B Bourgeois) (12/31/89)
[line eater food] I hope that someone who knows can comment further on this but I seem to remember that when the machine is powered up the keyboard does some self-testing which is signaled by the flahsing keyboard LED. I believe the 11 flashes may very well be a significant clue to where the error is. And to what it is. Can someone verify and amplify? What are the different flashes and what do they mean? Or am I all wet? Dana @ cup.portal.com
casebolt%esdc.span@fedex.msfc.nasa.gov (01/04/90)
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From: Kevin Stocksdale <kes%saturn.ACC.COM@salt.acc.com>
Newsgroups: comp.sys.amiga
Subject: A500 hardware problem
Message-ID: <7057@nigel.udel.EDU>
Date: 29 Dec 89 15:39:24 GMT
To: amiga-relay@udel.edu
Sender: amiga-relay-request@udel.edu
I have a stock A500 (with an 2002 monitor bought Nov. 1987).
Every couple of months a problem arises which can be fixed by
re-seating various chips.
When I turn the power on I hear the floppy drive click
every couple seconds (to determine if a disk is present).
The screen which prompts the user to insert the disk
a.) does not appear.
b.) takes a long time to appear.
c.) sometimes appears with corrupted color and vertical lines.
When the screen does not appear the machine fails to recognize
when I insert a disk. And on occasion the red power LED will
flash 11 times then it seems that the CPU gets reset and the
process repeats itself (no disk click when this happens).
Because of the frequency of occurence it would not be economical
to send it out for repair. Besides, I can resolve the problem
by pressing on a few chips.
Does the 11 flashes of the power LED signify something (diagnostic
code)? Does anyone have any suggestions as to which chip may need
replacing?
================================================================
Kevin Stocksdale Advanced Computer Communications
kes@saturn.acc.com 10220 Old Columbia Rd.
301-290-8100 Columbia Md. 21046
================================================================
Last week I repaired a friends A500 with the exact same symptoms!! Open the
computer (if it is out of warranty) and check around the disk drive where the
frame of the drive sits against board... Commodore or who ever left the leads
a tad too long (and sharp). On my friends machine, there was a strip of mylar
insulating the drive from the board. The leads of the components were sticking
thru the mylar and shorting (intermittently) against the drive frame!!
Also check the other leads of the components on the main CPU board!
Alot of them are too long and are possible sticking thru the mylar and shorting
out on the RF (metal) shield! I also touched up a few solder joints..(I don't
recommend this unless you have soldered before!!!)
Just take a pair of cutters and cut the component leads back a little!
This fixed my friends problem and will probably cure your sick A500..
Let me know if this was the problem...
Richard Casebolt
205-544-2966bleys@tronsbox.UUCP (Bill Cavanaugh) (01/05/90)
Just a note: I used to stuff circuit boards for a living, and believe me, in a modern shop, the length of the leads isn't under human control after the first few boards. There are "assembly aids" that move the board until the place for the component is centered, point a lighted arrow at where the component should go (polarity is indicated), move the drawer containing the proper component under your hand, and, after the component is placed in the board, bend and trim the leads. The finished board is inserted into a "wave solder" machine, which passed the board over aeater , then a few microns over a pool of molten solder, which follows the heat up the contact to the board. Once the lead length is set, whether right or wrong, it's set for good. Sounds like for that production run, "wrong" is the operative word... :(