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

Mark Vincent


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.


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