Author Topic: CPC664 membrane repair attempt  (Read 699 times)

0 Members and 1 Guest are viewing this topic.

Offline repetto74

  • CPC664
  • ***
  • Posts: 92
  • Country: be
  • Liked: 6
  • Likes Given: 0
CPC664 membrane repair attempt
« on: 18:46, 04 August 19 »
Hi guys,

After having successfully repaired a CPC664 thanks to the help provided here I am now trying to fix the keyboard as many keys does not respond. All key caps have been cleaned, membrane cleaned but mostly half of the keys are not responding to keystrokes. I have re-soldered the keyboard connector and cleaned inside with contact cleaner.
Is there any guide on where I have to look on the membrane tracks? Any schematics or tutorial on how to check this? :D 
As per the picture this membrane looks quality made. tracks are trapped into a double plastic layer and only pads and ribbon connectors are exposed so chances that tracks get damaged is very low I think. There is a 74LS145 which may decode key strokes so wondering if that could fail. I have tested the AY chip and it does respond to inputs from the joystick so I may have to consider it as good.

My idea is to try to use some conductive coating (acrylic+graphite mixed together).
« Last Edit: 17:38, 08 August 19 by repetto74 »