From: Spehro Pefhany
Subject: Re: Touch panel resistance???
References: <3DE45788.EDC5C68B@math.ucr.edu> <3DE5C1ED.E1C12A20@math.ucr.edu>
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Date: Thu, 28 Nov 2002 14:19:14 GMT
NNTP-Posting-Date: Thu, 28 Nov 2002 09:19:14 EST
On Wed, 27 Nov 2002 23:12:45 -0800, the renowned "Prof. Le Baron O.
>Thanks for the reply. I think I did not make myself clear
>in the post. This is a flat, very thin, membrane type
>switch with about 20 different switches built in to turnY
>lights on and off, enter numerals, etc. It is only about
>1/16 in. thick and is in the form of a sandwich of plastic
>layers. The conductors are put on with some sort of ink--
>maybe like the defrosters you see on the rear windows of
>cars these days.
Polyester screen printed with conductive inks, with a
spacer between layers.
> I am pretty sure it can not be taken apart
>without destroying it. I want to simulate the switch closure
>to be sure this is the problem. The switches are arranged in
>a matrix and the MCU controller cycles through constantly to
>see if any two lines are being shorted together.
Yes, that's quite normal. You *might* be able to get it apart
if you pull the spacer sheet from the backingPulling it from
the front will surely destroy the graphics, if nothing else.
But if the conductive ink is worn off, there's not much you
can (easily) do about it anyhow. The inks are hard to get,
and require oven curing.
>The best price I have found to replace is about $80 with tax
>and shipping. (Best was at Sears, BTW, even though it was not
>sold by them. It is a Whirlpool. About 10 years old. Magnetron
>is holding up fine.)
You can buy a nice (?) Samsung stainess-steel microwave for
not much more than that. Maybe ask around in sci.electronics.
repair, perhaps you can salvage one from a microwave with a
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