W5M Power Xfrmr Question

Skipp Tullen skipp at TULLENSOUND.COM
Sun Jun 29 20:55:42 EDT 2008


Hmm, I'd try Hammond Manufacturing Company, Limited  in Guelph,  
Ontario. They make a variety of small power transformers, one of  
which may be suitable for your amplifier.

Good luck!

Skipp, K2PXQ

Skipp Tullen
Recording Engineer/Producer
Tullen Sound Recording
26 Altamont Court
Morristown, New Jersey 07960-5325
(voice: 973-539-8120)



On Jun 29, 2008, at 8:38 AM, Jack Crenshaw wrote:

> 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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