C64 Diagnostic cartridge build

Time to make a C64 Diagnostic Cartridge using a Visible Solar System donor cart. Refer to my previous post about making a C64 Dead Test Cartridge if you need instruction on how to open it.

After opening the cartridge, see the front & back pictures.

DSC_0165 DSC_0167

The chip itself is partly soldered onto an adapter board, which is then soldered onto the cartridge PCB. The first step is to desolder the chip/adapter board from the cartridge PCB. I used my desolder station for that.




Now its time to program a chip. I used a 27C64 chip and programmed it with a MiniPro TL866 programmer.

I am going to program with the C64 Diagnostic Kit 326070-1 (Rev 586220/588220) rom. The file to use is diag-c64_586220 (zip)

To use a 27C64 chip some modification is required. See diagram below (from http://blog.worldofjani.com/?p=757)



To make the adapter I soldered some socket pins to the PCB, and used wires to join relevant points together. I place a couple of gaps in the socket pins in line with the adapter requirements.


Now we actually need to change the jumpers for the cart to work. The jumpers are labelled J1, J2 etc and need to be “open” or “closed”

For this cart the jumper settings are:

J1: Closed
J2: Open
J3: Open
J4: Closed
J5: Open

Either solder bridge the jumper pads to go from open to closed, or scraped away the small bridge to go from closed to open.

OK so we are ready to put back into the cartridge. I cut out part of the case because using the socket pins puts the chip up too high to fit in the case. There are neater ways to do this using adapters, but this works for me.




Note that the tests you can do with the cartridge are limited without the diagnostic harness. I will make a harness in the future.

See in the screenshot below some of the tests that have failed, this is due to the lack of a harness. However it is still useful for the tests it can successfully complete.





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