iz8dwf | Commodore SX-64 Executive repair. Yet another black screen. @iz8dwf | Uploaded August 2016 | Updated October 2024, 1 hour ago.
Commodore SX-64 Executive repair. Serial n. GA4011719.
Bad Kernel and Chargen ROMs. This time there was no need to use any particular test instrument to completely repair this computer. Of course having a good set of known good spare chips helps a lot.
Also, whenever one has an SX-64 on the bench, it's worth checking a PCB mistake that affects all (at least all I have seen) these machines: one of the 9V AC user port pins is connected to GND, on the original C=64 board, no 9V AC pin is connected to GND, so I break
the PCB track to eliminate this connection. If left connected, it could ruin some user port tools that expect no connection between 9V AC and GND and/or the SX-64 power supply (I never tried, but why taking the risk anyway?)
Replacement ROM with my own EEPROM board design here:
youtube.com/watch?v=kyXOuIfQgjw
Commodore SX-64 Executive repair. Serial n. GA4011719.
Bad Kernel and Chargen ROMs. This time there was no need to use any particular test instrument to completely repair this computer. Of course having a good set of known good spare chips helps a lot.
Also, whenever one has an SX-64 on the bench, it's worth checking a PCB mistake that affects all (at least all I have seen) these machines: one of the 9V AC user port pins is connected to GND, on the original C=64 board, no 9V AC pin is connected to GND, so I break
the PCB track to eliminate this connection. If left connected, it could ruin some user port tools that expect no connection between 9V AC and GND and/or the SX-64 power supply (I never tried, but why taking the risk anyway?)
Replacement ROM with my own EEPROM board design here:
youtube.com/watch?v=kyXOuIfQgjw
