One of my recent purchases on eBay was a Commodore PET 8032 which I planned to repair and bring back to life.
After opening up the PET I discovered it was hacked together from old parts. 4032 main board with some random ROM chips inserted with a 8032 CRT. Trying to find a replacement 8032 board is almost impossible unless you want to pay crazy money.
After pouring through the schematics, this got me thinking. I probably have most of the components already. Why not build your own main board. Looking through Google it seems no one has been crazy enough to do this yet. There is a modern replica of the 2001, but nothing for the 8032.
There are a few versions of the Commodore PET. The Universal Dynamic PET is probably the best choice as it’s compatible with the 8032 CRT.
The first hurdle was creating a replica of the PCB. With no bare PCB’s available to easily trace the one way to do this was to use hi res photos of the PCB and the schematic and reverse engineer the PCB. First was to create the schematic in KiCad and then use the image feature with the photos to replicate the exact traces on the PCB. This was trickier than I thought as tracing the bottom copper layer was easy, but the top layer was a challenge especially trying to guess how the traces ran underneath chips.
It also doesn’t help that the PCB and schematic doesn’t match 100%. I found a few design flaws on the PCB!
Took a few days to re-create the schematic in KiCad and then a few weeks to fo the PCB.
Once I’ve build the main board, and hopefully confirmed working, I’ll post a link to the gerbers.
Next step is gathering all the parts and seeing if everything fits.
First thing I’ve ordered is the heatsink. The closest I can find online is a C shape piece of aluminium 34.9mm x 25.4mm x 3.2mm which I’ll cut to length.
20 Jan 2024
All of the componets have been ordered. Some of the MOS chips are more difficult to find but managed to get them on eBay.
PCB has now been poplated, heat sink and regulators fitted. Starting to take shape and almost ready for initial testing.
Pingback: Repair Guides - Retro Electronics