WhitakerAudio J C Whitaker 20 W Stereo Audio Amplifier, Руководство пользователя

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• Disconnect the audio (program) source and wait about 30 seconds for RYL401 to open, as
indicated by a rising voltage on pin #2 of CONN402.
• Connect an audio signal generator to the right channel input. Set the output of the
generator to produce 1 kHz. Set the generator level for zero output.
• Slowly increase the generator output until the voltage at pin #2 of CONN402 goes to zero.
A value of 0.03 V rms is typical.
• Reduce the generator output by 2 dB. After about 30 seconds, the voltage on pin #2 of
CONN402 should begin to increase.
This test confirms the threshold sensitivity of the silence detection circuit, typically achieved
with the sensitivity controls (R402 and R408) set at mid-point.
– Potentiometer R418 sets the trip point for the bias sense circuit. With the amplifier
operating normally at a bias voltage of –30 V, slowly turn R418 counterclockwise until
the amplifier shuts down. Be very careful while performing this adjustment as high
voltages are present on the power management PWB and elsewhere.
– After the trip point has been identified, turn R418 1/4-turn clockwise. Reapply power and
check for proper operation. If the amplifier unexpectedly trips off, turn R418 further
clockwise.
– If a variable ac voltage supply is available, slowly lower the input ac voltage to the
amplifier from the nominal 120 V ac to 110 V ac, and then to 100 V ac. The amplifier
should continue operate normally down to about 100 V ac (maximum output power will,
of course, be considerably lower at low ac input levels).
Preliminary tests have now been completed. Next, detailed performance measurements should
be made.