In this detailed video from Reviving Retro, a problematic Commodore SX-64 lands on the repair bench. The initial complaint is a blank screen. However, the diagnosis quickly escalates. The display remains off, the drive LED stays lit, and the floppy drive spins endlessly. What starts as a simple fix soon turns into a full-blown Commodore SX-64 repair journey.
First, the host suspects the PLA chip. After testing, it turns out to be working. Focus shifts to the Kernal ROM. A diagnostic tool confirms it’s faulty and needs replacing. The SID chip is also tested and fails dramatically. Removing it allows the machine to at least boot—though with garbled visuals. A dead test cartridge reveals six RAM errors. The culprit is identified as UB6.
Solving Issues Step-by-Step
The RAM chip is replaced. But then, another issue appears—the screen stays black again. After some head-scratching, the host realizes the character ROM was inserted backward. Swapping it around solves the problem. The screen comes alive, confirming the fix.
Now it’s time to address the drive problem. The floppy drive spins nonstop, and its LED stays on. The host suspects the drive ROM or logic chips UE2 and UE3. Testing the ROM rules it out. The issue is with UE3, a 7707 logic chip. Replacing it with a reliable 7406 chip solves the problem. The drive returns to normal operation.
Final Restoration and Test
With the ROMs working, the SID removed, and new RAM in place, the SX-64 passes its tests. A final cartridge check confirms full functionality. The drive reads disks successfully. However, the eject spring may still need adjustment.
Throughout this Commodore SX-64 repair, the host demonstrates practical troubleshooting skills. Mistakes, like the reversed ROM, are shown unedited. These moments make the video even more valuable for beginners and veterans alike.
Conclusion
This video offers a hands-on guide to restoring a Commodore SX-64. It covers chip diagnostics, RAM replacement, ROM testing, and drive repair. Whether you’re fixing your own unit or learning the ropes, this repair walkthrough is worth watching.
