Restoring rubber keyboard on a logic analyzer

Electronics Plus sales at
Thu Apr 26 11:32:42 CDT 2018

Easier solution is to apply some conductive light lube. Radio Shack used to
carry it, and I repaired a LOT of remote controls with it!


-----Original Message-----
From: cctalk [mailto:cctalk-bounces at] On Behalf Of Peter
Coghlan via cctalk
Sent: Wednesday, April 25, 2018 4:17 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Restoring rubber keyboard on a logic analyzer

> I have a Philips logic analyzer (PM3585) which is about 20 years old at
this point.  It seems to be basically functional except for the keyboard,
which unfortunately is a critical part.
> This is one of those molded rubber type, with a circuit board behind the
rubber that has contact areas made of carbon film (at least they are black
in color) and on the back of each key a small cylindrical bump also coated
with carbon. Some of the buttons work but most don't seem to even if I press
> I've disassembled the keyboard, which was easy enough.  Inspection shows
no damage and no signs of corrosion or contamination.  I wiped everything
with isopropyl alcohol anyway.  The result is no change in behavior.
> Any suggestions for what to do next?

I had a similar problem with an old VCR remote control.  The problem seemed
to be that the bumps on the back of the keys lost their conductivity (and
cleaning them made them worse).

My solution was to glue pieces of aluminium foil to the back of the keys.
It was tedious but it seemed to sort it out.

Peter Coghlan.


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