Posted By
TLC
on 2009-06-13
15:37:48
|  Re: Cleaning the plus 4 keyboard
I'm writing from memory (I used to use a C-16 rather than a Plus/4; I only made this procedure on Plus/4 keyboards for few times and pretty long ago).
The flat cable connects to a socket on the mainboard; you can pull it off safely (putting it back will need more attention).
You can then separate the keyboard block from the top cover (also a matter of removing some screws).
To disassemble the keyboard,
1.) desolder, or cut wires that connect the shift lock key to the board (I'm not sure, but as I remember, even the Plus/4 keyboard has a shift lock switch connected to the board by wires),
2.) remove the screws that hold the board to the keyboard block,
3.) carefully remove the board -- you'll especially have to keep attention on not losing 1.) a small gold coated coil spring (about the size of the screws) somewhere in one of the corners. 2.) a couple of rubber bells (contacts) under the F and the cursor keys, at this point.
You can use domestic (neutral-ish) cleaning supplies to clean both the keyboard and the printed circuit board. This is to remove most of the dust and fat (which you'll find plenty of around and on the keys). Then dry them.
Clean all rubber gold plated contacts using alcohol. This ensures that all dust and fat is removed, whilst not dissolving the contacts  .
Carefully reassemble the keyboard. You might want to take pictures of the unit while disassembling, so that you'd have less doubts at this part . (Also, don't forget to put the small copper sheet spring, which is held by one of the screws, back to its place. The wires connecting shift lock will need to be soldered back (as far as I remember).
Thats's probably all...
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