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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 16th Apr 2018, 11:20 am   #21
Omegaman
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Default Re: Transformer Failure - why?

Could C25 have been the cathode bypass cap for the output valves?
It's common to take the heater centre tap to the cathode of the output valves to raise the noise floor.
Maybe when it was modified to fixed bias, this cap was overlooked and still in circuit but the resistor removed?
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Old 16th Apr 2018, 3:34 pm   #22
ronbryan
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Default Re: Transformer Failure - why?

I think that biassing the heaters to a positive potential above the cathodes is a trick to prevent hum.

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Old 16th Apr 2018, 3:38 pm   #23
HamishBoxer
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Default Re: Transformer Failure - why?

Thanks folks for that explanation.
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