[Amps] White Smoke

[Harold B. Mandel]

Dear Rich, 

Thanks for the reply.

The schematic of the xfmr, as supplied by PWD, shows the dual
primary windings "side by side" (however vertically) with the 
associated pin-outs corresponding to the original ALPHA 77
transformer plug. This means that the uppermost winding
has pin 6 on one side of the coil and pin 12 on the other, or lower
side of the coil. The lower set of primary windings has pin 9 at the
top and pins 7&10 both bonded to the lower coil wire.

This arrangement matches the pin out of the ALPHA xfmr plug
exactly, wherein the pins 9 & 12 are jumpered together for 240vac
service. 

Before connecting any a.c., a resistance check was made to 
verify continuity and lack of continuity between specific leads
just in case there was a primary-to-frame short, and to verify the
two primaries were indeed being connected correctly.

If a phase reversal occurred in winding the xfmr, the error was
embedded and the leads extended so that following the diagram
produced the damage. 

(Yes, no, Maybe???)

Thanks,
Hal

> >
> >         Doing a bench test of my new P.W.Dahl custom-wound
> > filament transformer with no loads attached the breaker was on
> > for under five seconds before the unit burned out.
> >
> >         A small puff of white smoke, a nasty smell and now
> > a fried transformer.  All the connections matched the PWD
> > schematic and the voltage was as specified for the primary
> > windings. The transformer had dual 120-vac windings that
> > jumper together just like the original ALPHA xfmrs so
> > 120 or 240 vac service could be selected.
> --  Were the dual 120vac windings connected in-phase or out of 
> phase?