W5M Power Xfrmr Question

[Jack Crenshaw]

Yeah, the power transformer in that amp is pushed very hard, and it has 
a history of failure.  I had to replace one years ago, and I've since 
seen several other W5M's with replacement trannies.  These days, I'm not 
sure where one would go to get one.

Jack Crenshaw

John Schmitz wrote:
> I recently completed rebuilding a W5M Mono Block and am extremely pleased
> with the sound quality of it. There seems to be just one problem. After
> running for several hours the power transformer gets HOT. I mean really hot!
> It seems way to hot for normal. All the supply voltages and ripple are very
> good. Sound remains outstanding even when the transformer is excessively
> hot. I tried letting it sit on, idling with no input signal for several
> hours and it still occurs. I thought maybe there might be shorted windings
> internally but voltages are right on. I calculated the idle current through
> the finals using ohms law across the 330 ohm common kath resistor and come
> up with 97milliamps, this seems reasonable. My next step is to measure
> secondary current flow by inserting an amp meter in the ground return center
> tap of the secondary. I'm expecting to see about 140ma, but I have not done
> this yet. My question is:
>
> Is the power transformer in these amps a weak point? Is it normal for the
> transformers to run so incredible hot or do I have a tired old transformer
> that has seen better days.
>
> John Schmitz
>
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