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Curing a recalcitrant Commodore keyboard

T

his is the process that I've gone through quite a few times now with Vic and C64 keyboards, as well as Plus/4 and C16. The results are amazing; the keys feel as-new and make contact every time with a light tap.

The computer being worked on here is another Vic from my deep stash. Most of my computers were collected for peanuts at car boot sales in the 90s, although one of these Vics (I don't know which one - possibly this one) is my original one. 

This involves a complete disassembly, requiring a key-puller to remove the caps, and the correct screwdriver to separate the PCB from the mounting bracket. It's also necessary to desolder the two wires from the bottom of the mechanical shift-lock switch. 

Cleaning the keycaps is a time-consuming job. I soak and scrub all faces of the caps. The legend on the top  is moulded in, so giving those a hard rub with a mild abrasive can only improve them. But this doesn't apply to the graphics printed on the front of the keys. Treat those gently and don't let an abrasive or even alcohol near them. I have light-brighted some particularly yellowed keys but most of the time this hasn't been necessary.
The bracket is still pretty dirty even after a pass with the hoover. That's best cleaned when everything is removed. I've not been able to get the shift-lock switch out of this bracket, so try not to get water into that. 
I clean this side of the pcb thoroughly, finishing with alcohol. Those contacts want to be as bright and clean as possible. It's probably not necessary most of the time, but I always re-flow those soldered connections. I've had one dodgy keyboard in the past (not Commodore) which kept me guessing for a long time until I found that the trouble was dry joints, which was easily sorted with the touch of an iron. So I always do it now, it can't hurt.
This is the real magic. I take a 4B pencil and rub it on some very fine wet-and-dry. This produces a fine graphite powder. I gently rub the rubber contacts on this toothy graphitey surface. This takes any glaze off the surface of the rubber contacts, 'keys' the rubber and works in a bit of that graphite. Finally I use the blunt pencil to rub the graphite in some more and clear away the excess.

Here's the reassembly with the washed bracket and keys. Note that there's one spring which is stronger and longer than the others - that one's for the space bar. 

Here's the result, which I'm incredibly happy with. For the record, I've also just cleaned both halves of the case, replaced electrolytic caps and carried out Noel's composite improvement. 
And for no reason, here are my sixtyclone and Vicky Twenty which both have old keyboards that have had the same treatment. 




 

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