Subj : Re: Commodore Pet keyboard repair
To   : James Harris
From : cbmeeks
Date : Wed Jan 10 2018 12:17:32

On Wednesday, January 10, 2018 at 12:17:06 PM UTC-5, James Harris wrote:
> To my surprise, I find I have a Pet which works - all apart from the
> keyboard, that is. So I have a query about fixing it.
>
> So far, I have removed the keyboard and found that the PCB contacts work
> if shorted with something conductive. Therefore the problem is with the
> little black pads that a keystroke presses against the PCB. I have tried
> these things:
>
> * cleaning with isopropyl alcohol
> * cleaning with contact cleaner
> * abrading with a pen eraser
>
> The latter was not really effective as there is too much give in the
> part of the key which supports the pad so I would say that the operation
> failed to abrade the pad successfully.
>
> Where I am now is that a few pads work but most do not. I have tried
> putting two meter test prods on the pads to measure resistance and found
> that some only become conducive with significant pressure. I guess that
> the rubber of some of them has become too hard with age.
>
> So what can I do to fix them? Any ideas?
>
>
> One idea I've had so far is to apply some conductive matter to the pads.
> I have tried a product called Keypad Fix on a remote but found it dries
> to be too inflexible and crumbles on use, albeit that that was on larger
> contacts.
>
> Another option is conductive paint such as
>
> https://uk.rs-online.com/web/p/solder-pastes/8352699/
>
> A further option is to cut tiny copper-film discs and stick them to the
> existing pads.
>
> Any of those good options? Other suggestions welcome.
>
>
> --
> James Harris

I have seen the 8-bit Guy use that keypad fix (or whatever it was called) 
before and it seemed to work.  However, I highly doubt he tested it much beyond 
the making of the video and who knows how long it would last.

I like the idea of using some copper foil or discs.  Perhaps epoxy a small 
copper pad on the bottom and try that?

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