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Ted Fletcher

Hmmm…. yes, that is certainly a problem with the power supply circuit; we did have some current capacity problems with the earlier P4 units and there were some modifications…. changes to component values.

The problem might be cured by replacing C21…. originally this was a 47uF 100V capacitor. On later versions I increased this to 100uF or higher.

If you still have problems, send me the unit and I will fix it free of charge…; no guarantees as I don’t know the current demand of those particular mics. But I would only charge just the cost of returning it to you. :)

(If you do change that capacitor, it’s worth changing the regulator transistor Q4 (2N5550) as well.)