20 Apr
2007
20 Apr
'07
10:43 a.m.
From: Warren Wolfe <wizard at voyager.net>
On Tue, 2007-04-17 at 13:13 -0400, Barry Watzman wrote:
---snip---
Hi
It is a common problem when dissimilar metals are in contact. I recall
working on a piece of equipment that someone had installed all gold
surfaced sockets. The parts were all solderplated pins. As you can guess,
it didn't work as expected. There were a lot of bad contacts.
As I've posted in the past, I've a solution that has worked well for me
over the years. I put silicon grease on the pins. This isn't heat sink
grease. That has fillers. The stuff I found works well is DoweCorning #4.
It is available at many electrical shops and places like McMaster-Carr.
Even though it is an insulator, it improves the electrical contact and
slows corrosion. I've used this on things like pinball machines and
computers( many of which are still running after many years ).
There are products that many HiFi shops have as well for this
purpose. I've never tried these but I'm sure they would work
as well.
Dwight
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The H-9 was flakey even when it was introduced.
It was not a reliable
product, and will probably be difficult to get working. Probably bad
ICs
or, worse, bad IC sockets.
On Navy ships, a large chunk of zinc is connected to the steel hull
at some point. Then, when oxidation, and other electro-chemical
degradation takes place, this "sacrificial anode" is where essentially
all the corrosion takes place. Every now and then, the remnants of the
zinc are removed, and a new block is attached. (It's VERY easy and
cheap to replace a block of zinc - repairing a thinning, corroding hull
is quite another matter.)
Somehow, I think the header pins on the H-9 were acting as
sacrificial anodes in that machine. You're probably in a MUCH better
position to answer this than I am. An H-9 was the first terminal I
OWNED to use with my IMSAI 8080. Previously, I had borrowed a Teletype
ASR-33, with the punch and all... whatever the exact model is. Anyway,
after about two or three days, I would literally have to take the damned
thing apart, and clean off all the headers (with long pins) by which all
the various boards were interconnected.