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Commodore PET 2001-8 Video Problems

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dwatts00

Member
Joined
Oct 18, 2012
Messages
15
Location
Leicester, United Kingdom
Hi All,

I could really use your help pulling this poor Pet 2001-8 back from the brink, can anyone diagnose his ailment from the pictures?

2012-12-04 16.00.07.jpg2012-12-04 16.00.23.jpg

I desperately want to be able to program on it.

Thanks,


David Watts
 
Just as an added question, my PET has an added board above the base motherboard which shares power and connects to motherboard via the side ribbon connection. Does anyone know what that is? This video shows a PET without one -
 
Sorry, I don't really know much about this stuff and to be quite honest I don't know where to start looking. So no, I am not kidding. But I would be happy for you to enlighten me if anything I said seems implausible.
 
dwatts00 said:
Sorry, I don't really know much about this stuff and to be quite honest I don't know where to start looking. So no, I am not kidding. But I would be happy for you to enlighten me if anything I said seems implausible.
Click to expand...
You want to know what the mysterious extra board is, so you post a cheesy video of a stock PET that does not have one?

And two different pictures of yours, with no explanation whatsoever of why they're different, what you did, etc.

Not to mention your location; where's A,A ?
 
Sorry, just watched that video with sound. I can see how it is blatantly cheesy. Pretty embarrassing, I posted at work where I have no speakers on my pc.

Just updated my location, perhaps A,A is the default as I don't recall setting it. I promise I am not trying to troll anyone.

The two different pictures are of the screen about 10 seconds apart, it appears to alternate between horizontal lines and vertical waves. I have not tried messing with major yet except cleaning and reconnecting all of the ribbon cables (it had no effect).

It appears I didn't start my plea for help off well, sorry about that again.

I would really like to find out if anyone knows the prime candidates for a video fault like this in a PET. If any more pictures (in better light) are needed, inside and out, I will be happy to take some tomorrow.

Thanks for any help.

David
 
No problem. And thanks for adding your location; it helps if something has to be shipped and sometimes you even find someone helpful in the same town.

I suspect it may well have something to do with that extra board, but without at least a picture of it there's not much to go on.
 
Leicester in the UK.

I will take some detailed component pictures of the PET tomorrow and perhaps video the screen so that people can see the strange progression.

The machine comes from an engineering department at a university where it was used up until 1996 believe it or not, it apparently had a program on it to control so machinery too expensive to replace.
 
Could be interesting since often machines in that environment have been modified; without the special software the modifications are usually useless, and it can sometimes be a challenge to restore the computer to stock.

Forget the screen video for now; post a detailed picture of the extra board in case someone recognizes it and carefully note down the details of how it connects to the rest of the computer because you'll probably have to remove it, at least temporarily.

Good luck!
 
Hi David, not quite in the same town but I grew up about 20 miles away between Uppingham and Corby. I get back there about twice a year to see my folks but I am now in Switzerland.

Without seeing it, there is a good chance your board is a 32k expansion board. It was a common add-on to 2001 PET's and they were usually on a ribbon cable on the expansion port.

Awaiting pics, Rob
 
dwatts00 said:
Leicester in the UK.

I will take some detailed component pictures of the PET tomorrow...
Click to expand...

I agree with Mike, a close up photo of the main board will help us use the correct schematic and know the types of ROM and RAM chips used in your machine. Here are links to PET schematics and some good reference books to download especially "PET/CBM Personal Computer Guide" by Adam Osborne.

http://zimmers.net/anonftp/pub/cbm/schematics/computers/pet/index.html

http://www.bombjack.org/commodore/books-kim-pet-vic.htm



The machine comes from an engineering department at a university where it was used up until 1996 believe it or not, it apparently had a program on it to control so machinery too expensive to replace.
Click to expand...

I wonder if the external hardware used the IEEE-488 port. I have seen some surprising applications using PETs as controllers.
-Dave
 
Wow, small world. If you get back in June next year we are hoping to have a 50 years of computing event at the university (it is actually 65 but 50 years since we have awarded a computing prize to undergraduate students), that is why I hope to revive and program the PET.

I did grab a picture of the whole machine the other day, just posting it because it is quite frankly awesome looking.

thepet.jpg

I will get potential problem solving picture tomorrow.
 
dwatts00 said:
Hi All,

I could really use your help pulling this poor Pet 2001-8 back from the brink, can anyone diagnose his ailment from the pictures?


I desperately want to be able to program on it.

Thanks,


David Watts
Click to expand...
I would take good pictures so you can put the add on card back the way it was, then remove it. What happens?

My guess from the pictures is that you have a bad cap here and there, depends on what the display looks like after the daughter board is removed. There are specific symptoms and their solutions pretty well known for this model, I bet you'll get this fixed if you can make a few board repairs. That of course assumes the computer itself is ok.
 
Hi All,

I took some pictures of the inside and a couple of extra ones to show the manuals and the back of the machine.

All of the innards, the extra board and close up of the gold chips that say 'mostek mk4215p-3' on them.

View attachment 11225View attachment 11226View attachment 11227View attachment 11228

I am a little ashamed to say that I mostly don't know what I am looking at here.

I have asked some of the techy guys here if they will look at the PSU becuase it looks a little.... errmmm .... old to me. At home I wouldn't bother but I don't want to burn the office down or blow the fuses. They said they could check it with an Osciliscope and perform a PAT Inspection (Legal requirement apparently).

The other pictures are of the back of the machine including serial and model numbers and the manuals that came along with it.

View attachment 11229
 
dwatts00 said:
Hi All,

I took some pictures of the inside and a couple of extra ones to show the manuals and the back of the machine.

All of the innards, the extra board and close up of the gold chips that say 'mostek mk4215p-3' on them.

View attachment 11225View attachment 11226View attachment 11227View attachment 11228

I am a little ashamed to say that I mostly don't know what I am looking at here.

I have asked some of the techy guys here if they will look at the PSU becuase it looks a little.... errmmm .... old to me. At home I wouldn't bother but I don't want to burn the office down or blow the fuses. They said they could check it with an Osciliscope and perform a PAT Inspection (Legal requirement apparently).

The other pictures are of the back of the machine including serial and model numbers and the manuals that came along with it.

View attachment 11229
Click to expand...

Looks like this hasn't worked, I will re-upload the pictures tomorrow since they don't appear to be working.
 
dwatts00 said:
Looks like this hasn't worked, I will re-upload the pictures tomorrow since they don't appear to be working.
Click to expand...
LOL; of course the only one that worked is one we don't really need to see. ;-)

Sounds like some extra memory on that board but it could still be a memory expansion or graphics board; looking forward to the pics, and you might also tell us what the numbers are on the ROM chips in row H.
 
Well here goes.

I took some pictures of the inside and a couple of extra ones to show the manuals and the back of the machine.

All of the innards, the extra board and close up of the gold chips that say 'mostek mk4215p-3' on them.

chips-on-extra-board.jpgpet-extraboard.jpgpet-mainboard.jpg
 
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