Greetings all,
I am Resuscitating my 3 pcs APT Holman power amps, the usual oxidized relay contacts and discovered an intermittent dual PCB mount RCA jack, resoldered the PCB traces. Works fine.
re the trimpot adjustments, Seeking the recommended procedure to set offset and bias trimpots. Suggest to replace original 1 turn trimpots with multiturn?
First preheat amp at modest load? 10W?
Adj offset to 0 DC out +/- 10...20 mv?
Adj Bias: preset pot for 20 ma quiescent current
Set generator for 1 W output power at 1 kHz?
Use THD analyzer, observe residual THD products.
Trim bias control for lowest zero crossing distortion?
Readjust offset after bias?
Have original user manual, but not service manual.
MANY THANKS
Jon PAUL
Crypto-Museum
I am Resuscitating my 3 pcs APT Holman power amps, the usual oxidized relay contacts and discovered an intermittent dual PCB mount RCA jack, resoldered the PCB traces. Works fine.
re the trimpot adjustments, Seeking the recommended procedure to set offset and bias trimpots. Suggest to replace original 1 turn trimpots with multiturn?
First preheat amp at modest load? 10W?
Adj offset to 0 DC out +/- 10...20 mv?
Adj Bias: preset pot for 20 ma quiescent current
Set generator for 1 W output power at 1 kHz?
Use THD analyzer, observe residual THD products.
Trim bias control for lowest zero crossing distortion?
Readjust offset after bias?
Have original user manual, but not service manual.
MANY THANKS
Jon PAUL
Crypto-Museum
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