bad keys on terminals

[Allison]

>
>Subject: Re: bad keys on terminals
>   From: "Dave Dunfield" <dave06a at dunfield.com>
>   Date: Tue, 12 Sep 2006 05:31:07 -0500
>     To: "General Discussion: On-Topic and Off-Topic Posts"	<cctalk at classiccmp.org>
>
>
>Dave
>
>BTW: I have similar vintage PETs with identical keyboards in
>which the conductive rubber is fine ... anyone know what
>conditions accelerate the deterioration of conductive rubber?
>

Ozone and other airborne contaminants.  I have a old (30 years old)
peice of black conductive foam that is stored in a large jar with 
cmos parts and some dessicant is in perfect condition.  A peice 
from the same block exposed to the air died (crumbled) over 15 
years ago.  

I've also had several keyboards with foam backed pads (Cherry?)
die on me.  Same problem, either the glue dies or the foam.


Allison