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Posted by DoN. Nichols on April 28, 2008, 5:30 pm
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> I'd have to agree with the majority - the former owner has already
> tried swapping boards, so odds are it's not a board. Bad power SCR or
> Triac in the output sections, bad potentiometer or cabling in the
> controls, bad safety switch, open coupling capacitor, bad
> opto-isolator, etc.
>
> Do a methodical search and you'll find it.
>
> That, and/or make like Jimmy Durante and follow your schnoz - if a
> component has met an electrically violent end, the nose knows. Stuff
> your proboscis in there and take a deep sniff, and track down the
> crispy critter.
Well ... resistors and perhaps caps (depending on the type) will
show up -- including pots.
But SCRs and the like tend to fail in such a way that the smoke
does not really escape, but is rather trapped where it does no good --
and gives no clues to the nose. (Though it may cook the insulation off
the wiring, which you can smell. (If the wiring has Teflon insulation,
you better hope that you *don't* smell it cooking. :-)
And I have seen high voltage silicone insulation get the wire
zapped from inside it without opening at all -- the insulation just
turns limp in certain areas. Not too sure how many welders would be
using that insulation -- it was rather uncommon and expensive when I was
using it at work -- and we were normally routing 45KV with it, a bit
beyond what you would see in the typical welder. :-)
Enjoy,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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> tried swapping boards, so odds are it's not a board. Bad power SCR or
> Triac in the output sections, bad potentiometer or cabling in the
> controls, bad safety switch, open coupling capacitor, bad
> opto-isolator, etc.
>
> Do a methodical search and you'll find it.
>
> That, and/or make like Jimmy Durante and follow your schnoz - if a
> component has met an electrically violent end, the nose knows. Stuff
> your proboscis in there and take a deep sniff, and track down the
> crispy critter.