The only rational course of action at this point would be to give up
and dump the amp at the offical Heath Disposal Site (which is
conveniently located at my house). :-)
I would check the rectifier diodes to see if they are shorted. If not,
I would then disconnect all of the power transformer outputs and test
it by itself. If it is ok, then check the downstream circuitry for
shorts. Isolate components to make it as foolproof as possible -
ideally checking each one by itself. If it were me, I would replace
the transformer anyway since it's been smoked - even if was not the
root problem.
Michael
--- Heath Albritton <halbritt@harm.org> wrote:
>
> I've received an SB-220 from a friend in non-working condition with
> the advice
> that the filter caps were bad and that I should get the replacements
> from
> Harbach, which is exactly what I did. After installing the new caps
> from
> Harbach and powering up the amp on 240VAC the amp did nothing more
> than throw
> the circuit breaker. After a couple of attempts while trying to
> troubleshoot
> various things the smoke escaped from the transformer. As I
> understand it,
> this sort of behavior is non-optimal and probably indicates that
> there is a
> problem with the plate transformer.
>
> In retrospect, I realized that I probably should've tested the old
> filter caps
> before I had ordered replacements. After checking them with the cap
> meter,
> they all tested good. At this point, my main question is what is the
> best path
> to determining and resolving the problem with the plate transformer.
> Can
> anyone give me specifications on what the resistance should be on the
> primary
> and secondary? I assume that my problem is a short somewhere and
> that I should
> be able to determine that with an ohm-meter. Assuming that there is
> a short in
> the transformer, is there anyway to get the smoke back in? Is it
> possible to
> fix by hand? I suspect that even if it is possible to rewind it by
> hand that
> it would probably take more effort than it was worth. I've seen
> original (used
> or NOS) transformers for sale for around $150 and I know that Peter
> Dahl makes
> one that runs about $255. What would be the wisest course of action
> at this
> point. Any advice would be appreciated.
>
>
> Thanks,
>
> Heath Albritton (KG6GTX)
> _______________________________________________
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> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
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