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Commodore SX-64

Computers in Collection

Purchased at 2018 Portland Retro Gaming Expo. Everything works! It’s just kinda broken/ugly.

20181122 Cleaned the keyboard, down to the membrane and PCB.

Membrane came apart with very careful peeling and a guitar pick to help in sticky places. The keyboard still has a problem with connecting between the membrane and PCB. There’s some residue on the PCB contacts, presumably carbon from the membrane. Several keys still don’t work because of that. And the metal plate that’s supposed to push the two layers together don’t seem to thread. Not sure if I stripped them or the screws are the wrong size. Probably the latter, because the screws seem very loose in the holes now. I’m entertaining using Z-axis tape to fix this once and for all.

20181123 Cleaned virtually all plastic parts. Cleaned and lubricated floppy drive. Cleaned CRT cover glass.

Interesting observations:

  • CRT is covered with glass that is tinted. Mine appears to have some small worn-through areas in the tinting.
  • CRT cover glass held with three clips that pop off with a flat-head screwdriver.
  • Back panel/heatsink/power supply can be held on with two screws, makes handling the disassembled unit much easier.
  • Removed two switches installed in the storage tray. One switch was wired to toggle between floppy drive IDs 8 and 9, via a jumper that was cut on the floppy controller PCB. The other disconnects write-protect detection.
  • Erratic keyboard connector on main chassis was due to two of the DB-25 connector pin sockets being pushed out of the housing a couple of millimeters. Pushed them back in, and all is working well (disregarding the issues with the keyboard itself).

20181204 Removed floppy write-enable switch, repaired wiring to detector. Replaced drive ID 8/9 switch, added heat shrink strain relief to switch pins. Reassembled case bits. Repaired keyboard interface between membrane and PCB using 3M 9703 Z-axis tape – and it works well! Some of the material on the membrane came off during the first attempt at Z-axis tape. But that thankfully did not destroy the interface. Whew.