Re: Keypad problem ?


Joe Zeglinski
 

Hi Dominik,

Glad to hear that all is well, after the fix.

For the rest of us, perhaps, you could clarify, just in case we run into a
similar problem. In anticipation of other's questions, (Marj was not quite
clear on your post), perhaps we have a very slight misunderstanding in
translation - when you mention "silver" traces.

I have never seen "silver" used in PCB contacts or traces on circuit
boards - they are either gold plated or beryllium plated contacts, and circuit
traces were, until recently perhaps, always lead/tin solder. I wonder where
the "silver" comes in to play. Unless, silver is being used somehow to replace
solder, in order to meet Europe's ROHS pollution standard - an expensive
solution, but this board likely predates that requirement.

Also, circuit traces, even if they are the "old solder standard", are
almost always covered by a green layer of protective "conformal coating", on
good quality circuit board products, which must be standard for Astro Physics
products, surely.

So, I don't quite understand where your friend found anything "silver". Is
it possible that he is using our Polish term "srebny", which describes things
that are "silver coloured", in referring to the "colour" of solder (traces)?
Even so, I am surprised he could get to the solder trace without some effort
to scrape away the green conformal coating, painted over it.

Be that as it may, it would appear that there was a possible bad spot in
the "wave soldering" of the board, leaving a short segment of the original
"copper trace" on the etched PCB exposed, which obviously has corroded over
the last 5 years, or more. This break in the trace caused a loss of some
signal in the Keypad circuit, which your friend expertly cleaned and
resoldered - he has a good eye to have spotted it. Now everything is operating
normally.
If so, I wonder about the quality checks made by the original keypad
manufacturer.

Have I got this right?

Anyway, I probably just made a short story ... long ;-)
Best regards,
Joe (a.k.a. Jozef)

----- Original Message -----
From: "Dominik Wos" <dominik@derpal.com.pl>
To: <ap-gto@yahoogroups.com>
Sent: Tuesday, April 17, 2007 5:27 PM
Subject: [ap-gto] Re: Keypad problem ?


Czesc Jozefie,

U mnie wszystko OK. Dzieki :-)

So where the problem was ? According to my neighbour the plastic
keypad which is inside is very sensitive to corrosion (he
manyfactures electronics for agiculture machines and uses this kind
of products). The paths are made from silver. Accourding to him it is
a rather common problem esspecialy that I bought my mount second hand
and I belive it is 2002.

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