26 Oct
2004
26 Oct
'04
3:12 p.m.
I've popped it open and some of the ICs (mostly
TTL) have corrosion on
the leads. I have a few opening questions for others who have
restored hardware in similar condition: should I remove the corrosion
on IC leads, or do I run the risk of 'removing' the leads. The
circuit boards look really good, so worst-case I will replace some of
the chips.
What is the opinion about this kind of servicing? The chips in
question are all (so far as I have investigated) common 7400 series
(some Schottky) TTL gates. Do people consider it as 'damaging' to the
'credentials' of a piece of classic hardware to replace chips with
others with significantly different date codes?
Well, I don't go around replacing good chips :-). But I do feel that if
at all possible my classics have to work, and that means replacing parts
if necessary. My rule (of course) is to replaced the least amount
possible -- that it to replace a chip rather than the entire board. And
no, I don't care about date codes, or even families (in other words I
might put a 74LS-series chip in place of a plain 74-series one if it
would work). In fact I have an HP9810 calculator (1972 vintage) with the
odd 74Fxxx chip in the processor for that reason.
This is going to be a long term project for me, I
fear, because I want
to do it right. This machine has a built-in CRT display so I might be
All I can say here is that it often takes me a couple of months before
powering up a new toy. Better to be patient now than to have to track
down irreplaceable parts...
My MDS800 is the older one without the built-in terminal. I don't have
the Intel terminal for mine, I just use a PC running a terminal emultor
forced to do some (something I almost always refuse to
do these days)
video monitor troubleshooting.
Ah :-). Monitors actually are not that bad to work on.
-tony