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CBM PET 8296 RESTORATION

Desperado

Desperado

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Nov 25, 2017
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Good evening everyone, this time I really need help to try to restore this Cbm 8296 that I bought for a few bucks. Today it was delivered and as soon as I opened it, I noticed that some ICs are missing and that some power wires are disconnected. The keyboard cable is also disconnected. Is it a possible job in your opinion? Where do you recommend starting? Thank you very much!
 

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If you get something tampered with like this, the best move before you start is to put everything back to original as possible and replace any missing parts. If you find mods that are not standard, undo them, but keep a record of what was there. For example if you find mods with link wires, check for associated cut tracks. Keep in mind some people cut tracks by drilling out vias.
Then, as usual start from the beginning, make sure the power supplies are working properly and work your way through the computer in the usual way fault finding it.
 
The first issue I think you may have is that looks like the 8296-d motherboard and not a 8296 … so the power supply is wrong and also a resistor link for the video has to be changed. You can convert it to 8296 by adding components to the power supply circuit but not sure worth it. Do not plug in the transformer unless you have checked voltages are correct for the 8296-d spec input

The 8296-d has in built dual floppy drives… seems this board was moved from one of those into this. If plugged into the transformer incorrect voltages may have been applied across the board … who knows
 
AndyG said:
The first issue I think you may have is that looks like the 8296-d motherboard and not a 8296 … so the power supply is wrong and also a resistor link for the video has to be changed. You can convert it to 8296 by adding components to the power supply circuit but not sure worth it. Do not plug in the transformer unless you have checked voltages are correct for the 8296-d spec input

The 8296-d has in built dual floppy drives… seems this board was moved from one of those into this. If plugged into the transformer incorrect voltages may have been applied across the board … who knows
Click to expand...
Ops....thanks for the warning! Is there any way to tell for sure if this is an 8296 or 8296D board?
 
Well I can say 100% the board is for the 8296-d. Cannot say If anyone modified the transformer ....
 
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The power input pins on the motherboard are shifted compared to the 8296 as it has a different power supply. Not by drawings so cannot tell the voltages but it is different
 
Yep ... the case and mounting position for the power supply are different for the 8296-d
 
Google it and you will see

I know as I got a 8296-d but the previous owner swapped out the ram chips and made a right mess of the board. So I converted a 8296 to 8296-d spec by removing components on the power input side and changing the resistor link for the video which is inverted. Know idea what's been done to the board you have.
 
Thanks, but is it possible to insert the power supply on this case or is it not convenient?
 
Doubt you will find the correct power supply anywhere so may have to put on together which up to you. I recommend finding another 8296 board
 
Would it be possible to use a PC power supply? What voltages would it need to supply to make this card work?
 
Need to check the drawings. Am not near them .. in my head think 5v and 12v but needs checking to be sure. You also need 2 PLA chips which you can get on eBay and usual EPROMs to build the basic and edit rom set. Also a character rom and replace the two missing IC's that have green sockets. Seems this board has been harvested for IC's which puts a question mark on it.
 
I'm afraid the only solution, the simplest one, is to resell the computer as is. More experienced people will be able to get it working again.
 
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