Re: PG506 Repair - I had a Great Day today/


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The *Peak* voltage of a (true sinusoidal) AC signal is 1.4(something)
times the RMS voltage (the point that most AC signals, transformers, etc
are rated at) so the caps MUST be rated at more than 1.4 times what the
transformer output is. I would go with caps rated at at least twice the RMS
voltage.

My $.02 worth,

On Mon, May 3, 2021 at 1:26 PM Mark Vincent <orangeglowaudio@gmail.com>
wrote:

Rene,

I see you said you recapped the unit. For the caps in the primary power
section, they should be a low ESR high temp type, e.g. Nichicon ULD, UCY,
etc.

Mark. You may have used this type already. The one for the 120V supply
should be 200V. The heat will reduce with low ESR types provided the rated
voltage on the caps are high enough. If the voltage is lower than the peaks
of the unfiltered ac, it heats the caps up and causes higher power to be
dissipated in the driver transistors and transformer. For square wave
oscillation, the minimum rated voltage for caps is 1,5x the rated ac
voltage from a winding. It is possible the additional heat is from a ,1mfd
that is leaking that is on the -72V line.

Check VR210. If that is bad, the AMPL VAR, R225A, will not work right.
Michael Lynch is right about checking the diodes.

Mark





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