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Re: Copland CTA 505 electrica scheme

Valeria, I have owned this amp for apprx. 4 years and love it!

The instructions for biasing the 2 12aw7 tubes are as follows:

The trim pot P3 in left channel and P103 in right channel
are adjustments for the phase splitter bias current.

Find the test point marked P L in left channel and P R in
right channel,they are located at the position of R10 and
R110 ( 22Kohms 3W resistors).

Place voltmeter probes over the resistors, or between
ground and the resistor legs were the test point marking
is.

Adjust the trimmers until you read 114,2 V. DC. in each
channel.

Please advise if I can be of further assistance.

Richard


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