What's your specialty?

From: Tothwolf <tothwolf_at_concentric.net>
Date: Fri Feb 8 20:03:33 2002

On Fri, 8 Feb 2002, Tony Duell wrote:

> > Sounds like the same reasons I write code. My favorite stuff to work on
> > are old boards full of nothing but logic gates and such. Modern gear
>
> Mine too... Which is why I like the PDP11/45, PERQ, PDP8/e, etc.

Sounds like I need to learn more about DEC's older systems.

> > Or, the part is so expensive, that replacement would cost more than the
>
> Sometimes even then I just replace the part.... It may depend on what
> I have in stock -- if I have the part then I'll use it to get running
> again as soon as I can.

If I actually have the part, I'd repair a board, but if I have to go out
and pay more for the part than a whole board, I might not.

> > whole board. In those cases, I pack the board away in a box with a note to
> > myself as to what is wrong with it and why I didn't repair it. I've later
>
> Yes, I've got a number of boards like that. Mostly HP
> calculator-related (these machines have a lot of custom chips for a
> good reason). Things like an HP45 logic board with 'bad A&R' written
> on it (A&R == Arithmetic and Registers == the data path of the CPU)

I have a few myself, but the number has shrunk in the last few years as I
started repairing more of them. The next big investment I need to make is
in a hot-air soldering station. It would allow me to repair a number of
boards and drives I currently have packed away.

> > repaired some boards like this, when the parts that were needed eventually
> > turned up.
>
> Alternatively they can be useful as a source of other custom parts...

Especially when you have other functioning units that are in use in
equipment.

> > I'm the same way. If it isn't potted in epoxy, I can repair it. I've
>
> Hmm, I'm not that good yet... I don't have the equipment to rebuild
> CRTs at home, for example :-)

I don't yet have that equipment either, but it is certainly on my list ;)

I hope eventually to also have the equipment and space to repair older
hard drives.

> > repaired a few small bits of stuff that were potted, but larger stuff is
> > somewhat difficult to unpot w/o damage. I've heard there are some solvents
> > that will soften the compound to allow it to be removed, do you know what
> > those might be called?
>
> I am told glacial ethanoic (acetic) acid is one thing that's sometimes
> used. I've not tried it though.

I guess I'll have to do some research and find a suitable
victim^Wsubject^Wboard that I've stored away somewhere to test on.

-Toth
Received on Fri Feb 08 2002 - 20:03:33 GMT

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