Calibrations And Adjustments - Classe Audio CA-201 Service Manual

Calibrations and Adjustments

Bias adjustment:
Note: Bias adjustment should be made without any load connected to the amplifier's output, and no signal
connected to the amplifier's input.
1. Connect a multimeter to R4 leads and set the multimeter to mV scale.
2. Turn trimpot RV1 counterclockwise until it reaches 0 . A click should be heard.
3. Turn on amplifier, and let it warm up for 15 minutes on idle.
4. Adjust trimpot RV1 to get a 14mV reading.
5. Let the amplifier warm up for a 24 hours period with signal and load.
6. Remove signal and load, and reconnect the multimeter, setted to mV scale, to R4 leads. Note the
reading.
7. Connect the multimeter to R4, R5, R6 and R7 leads. Note the readings.
8. Input the results into this formula:
((96 – mV
9. Connect the multimeter to R8 leads, and adjust RV1 to match the reading to the formula result.
10. Results should be around 24mV.
DC offset:
Note: DC offset adjustment should be made without any load connected to the amplifier's output, and no
signal connected to the amplifier's input.
On these units, DC offset can't be adjusted. Measure DC offset using a voltmeter connected to the output
posts, scale setted to mV. DC offset should be less than 10mV.
PRO-SVR_LEGACY
– mV – mV – mV
R4 R5 R6
) ÷ 4) + mV
R7 R4
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