Collection policy was Re: No space for vinatge computers in

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Mon May 26 17:30:00 2003

> > Even then you'd not be totally lost without a schematic if you knew the
> > type of valve that was supposed to go there (quite likely to be a double
> > triode, actually). The heater connections should be darn obvious, and you
> > can easily distinguish grid from anode from cathode with a little
> > practice. The only problem would be keeping the right anode/grid/cathode
> > together.
> I'm not that good with vacuum tube circuitry, but if the computer is based
> on digital logic or microprocessor technology and the parts are available,
> I'd at least have a go at fixing it. Now I've developed a trick for getting

I'll go further than that -- I'd have a go at fixing just about anything.
Being able to get the right spares and having the original schematics and
service manuals helps, but it is not essential (as I have proved many
times :-))

> the parts that are to be replaced out of the PCB without FUBARing it...

The best way I've found for pin-through-hole DIPs is to suck off all the
solder I can with a good solder sucker [1], and then to press the leads
inwards towards the body of the chip on the component side to break the
remaing bit of solder. The chip then comes out without damage.

[1] A smear of petroleum jelly (vaseline, etc) on the O-ring of a solder
sucker really improves it!

> Valve overheats, base was (hypothetically) made of crappy materials, base
> cracks, then the heat of the valve cracks it in half or whatever.

I have _never_ seen this happen, and I run a lot of valved equipment still..

Anyway, if this happened, I suspect you'd still be able to see how the
parts should fit together, and thus would be able to record which wires
went to each pin.

-tony
Received on Mon May 26 2003 - 17:30:00 BST