[Milsurplus] 1MC system and B+ problem

[J. Forster]

Yes.

Bring the line voltage down to where it is supposed to be, around 110 VAC.
>From what I'l told it is running 130 - 135 VAC.

-John

=================



> I had the thrill yesterday of sounding the general alarm on the
> WWII-vintage 1MC system aboard MASSACHUSETTS.  500W from 4 push-pull,
> parallel 838s.  "This is just a test, DANG DANG DANG....."
>
> Rather annoying problem with a second PA unit that we were trying to get
> running again.  After isolating a leaky filter cap and everything
> downstream from the rectifier, we were still blowing fuses when we put the
> B+ on.  We could run the HV transformer alone, disconnected from the 866A
> rectifiers or even with either side of the transformer connected, but with
> both sides of the transformer connected to the rectifiers we got a lot of
> current as indicated by bright purple flash in the rectifiers before the
> HV primary fuse blew.
>
> We suspect an arc in the rectifier filament transformer, which shows no
> sign of leakage from the rectifier winding to the case or any of the other
> windings under test with an ohmmmeter.
>
> The next step is to try replacing the filament transformer, which also
> runs the 838s, with a seperate winding for each 838 filament.  Weighing in
> at something like 50lb and located just above the deck, this is what we
> call fun.
>
> Anyone have any other suggestions?
>
> RF
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