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Restoring a 2001 chiclet

Do you mean RIGHTmost sockets? (I1 and J1)? I thought I'd read that somewhere else.
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Yes, you are right. I'd mentally got I1 and J1 on the left for some reason. :oops:

do you know off the top of your head which legs that is? I'm old and forget such things...
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Check all 4 rails, they supply different components. It varies from chip to chip. For the 6550 ram's it's pin 17 according to the schematics on zimmers http://zimmers.net/anonftp/pub/cbm/schematics/computers/pet/2001/320008-2.gif

oh yes, and when it froze up, I think the cassette motor started up too, that is, it worked fine, then froze, then the motor started, then I switched it off. Does that suggest the PIA chip (facing towards the tape deck) needs attention?
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Possible, but check the voltages first.
 
Am getting 5.02 v from the regulators.
If I piggyback the video ram with any of the memory ram, the characters on the screen change, then revert when I remove the piggybacked ram. Does tha help at all?
"I feel your pain"
Yeah! It's so annoying. I wish I'd stuck with less memory but a working machine...
 
I think my next step is to remove the motherboard and check each Ram and ROM socket for bad connections.
Might be. A while, so in the meantime any input on my issues would be welcome!
Thanks guys
 
If I remove the video ram, the screen shows all left arrows in reverse (black on White)
Isn't it supposed to be a checkerboard?
Is that a clue?

I'll check the 6550's are getting power too.

I've checked all sockets in hij 123, videomram and character generator. all are maKing connections from top of chip leg to motherboard. More later...
 
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Good news.
Received Gubbish's excellent petvet.
Plugged in, and my pet now works with 32k!
Great. Thanks!!
Now, clearly then my issue is with ROM or RAM.
Question is, do I try to find out what the problem is, or leave it as is (so not risking damaging anything while checking)
My view? Leave as is.
 
Also using the petdisk. Excellent. Both recommended.
When I first connected it, I got device not found, I cleaned my cone toons.....and it worked fine!
If you have a pet and don't have a petdisk, well, get one.
 
Now that you have your PETvet installed, you could use it to pinpoint the bad RAM or ROM on your board by selectively setting different sections of ROM to pass through to the PET motherboard. When you get to a section that stops the computer from working, you've found the culprit. Let me know if you're interested in pursuing this and I can show you how to build different ROM settings to do this.

Also working on a 6502 assembler program for the PETvet to test the mainboard ROM and RAM and check against the onboard ROM contents. Will keep you posted as that develops. Real-life work is crazy for me for the next couple of weeks though, so probably won't get to it before the end of this month.

Have fun with your PET!
 
gubbish said:
Now that you have your PETvet installed, you could use it to pinpoint the bad RAM or ROM on your board by selectively setting different sections of ROM to pass through to the PET motherboard. When you get to a section that stops the computer from working, you've found the culprit. Let me know if you're interested in pursuing this and I can show you how to build different ROM settings to do this.
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I'm certainly interested. I don't want to hijack Chandler1's thread but now I've got to grips with my PetVet, that would be really useful to know how to do this. I assume it means rebuilding the ROM images or can you do it in real time via the serial cable?

Rob
 
I've just seen 700 odd views of this thread. I expect a lot was found on google searches. To anyone who gets here that way,and who may have viewed thisand other posts on the chic let repairing, they may feel a,little cheated that sem threads just stop when a solution is found, even if the solution isn't posted.
Anyway, my input on the matter is this.
Reseat the chips. Clean up all connections. Test the voltages to each rom and ram chip, and then buy a PetVet if you believe the problem is rom/ram, and especially if you are getting random characters on the screen.
I'm not an expert, or even a starter, so make your own choices, and good luck!
 
gubbish said:
Now that you have your PETvet installed, you could use it to pinpoint the bad RAM or ROM on your board by selectively setting different sections of ROM to pass through to the PET motherboard. When you get to a section that stops the computer from working, you've found the culprit. Let me know if you're interested in pursuing this and I can show you how to build different ROM settings to do this.

Also working on a 6502 assembler program for the PETvet to test the mainboard ROM and RAM and check against the onboard ROM contents. Will keep you posted as that develops. Real-life work is crazy for me for the next couple of weeks though, so probably won't get to it before the end of this month.

Have fun with your PET!
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Actually, I would be interested in finding exactly what the issue is, so whenever life allows (I know that feeling) please do expand.
Many thanks again!
 
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