On Dec 18, 0:07, Johnny Billquist wrote:
> On Mon, 17 Dec 2001, Pete Turnbull wrote:
> > Domestic ones I've seen won't. Apart from the soaking -- that's the
point
> > of using it, obviously. Very few things are intolerant: some relays,
> > transformers, a few types of switches, etc, usually just because they
take
> > too long to dry out. And core mats, of course, because they're very
> > fragile and extremely hard to repair.
>
> Don't forget old transformers, which often use something looking very
much
> like paper for isolation.
Agreed. That's why my PDP-8/E's H740 power supply got a different
treatment. It still got washed, though.
> > > Grab a bottle of isopropanol, some swabs, and start working.
> >
> > Doesn't work well on smoke-damaged boards, Coke, etc, and water is far
> > cheaper and safer (for the user, too).
>
> It works, but it requires more work.
It doesn't work very well. It's almost impossible to get all the crud out
from under ICs, DIL switches, or sockets. IPA does not do a good job on
smoke-damaged boards.
> > TTL may be
> > much less sensitive than old CMOS and even modern CMOS and TTL
> > replacements, but it is still sensitive and can be damaged by ESD.
It's
> > not so likely to be damaged when soldered into a complete circuit, but
it's
> > possible. I've had at least two QBus boards damaged by ESD through
> > careless handling.
>
> Eh? Q-bus cards, even the oldest you can find, are LSI stuff. You won't
> find much of anything even *that* modern in a PDP-8. Actually, much Q-bus
> stuff is really modern compared to what I'm thinking of...
Plenty of QBus cards use TTL, basic 74 series, not just LS. I just pulled
a few out to check. In the faulty ones I referred to, it was some TTL
PROMs in one of them that had gone (lost several bits), and I can't
remember what was wrong with the other one. Nevertheless, even original 74
series TTL is static-sensitive, and the worst part is that things can be
degraded by ESD without failing completely. That's why modern circuits
include extra ESD protection.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Mon Dec 17 2001 - 20:06:20 GMT