SX-64 Black Screen Issue

twoodland · May 29, 2019

Good day everyone,

I have a friend who contacted me recently. She dug her SX-64 out of storage that she bought new to run some games that she enjoyed playing some years before. She turned it on, and only gets a black screen (well, she described it as a white screen because she turned up the brightness when it didn't display anything).

I told her that I would look at it, so I drove over to check it out. I confirmed that it displayed a black screen, no garbage. When I took the cover off, the rail on the right (from looking from the back of the unit) was broken. I asked her if she or anyone had it apart, and she told me that to her knowledge it had never been opened. The inside looked all original and I did not see anything that had been replaced. I spent some time cleaning it and checking all of the wire and board connections. I started to re-seat the socketed chips. The CPU board is a Rev A and I noticed that the 6510 MPU (ceramic type - original?) had thermal grease on the legs. I took it out and saw that the rightmost bottom leg (2?) was bent under the chip not inserted into the socket. I carefully straightened the leg and re-inserted it into the socket. No Change in symptoms.

I tried taking out the SID, no change. I swapped out the PIA, no change. I swapped out the Kernal, no change. I am unable to locate a MPU to swap it out and I do not have the diagnostic cart & cables.

Does anyone know where I can get a replacement MPU? If I can get a replacement and if it does not fix the issue, what should I try next? Does anyone offer diagnostic services?