Calibrations And Adjustments - Classe Audio CA-100-101 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 R120 leads and set the multimeter to mV scale.
2. Turn trimpot RV102 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 RV102 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 R120 leads. Note the
reading.
7. Connect the multimeter to R120 and R122 leads. Note the readings.
8. Input the results into this formula:
((48 – mV
9. Connect the multimeter to R120 leads, and adjust RV102 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.
1. Connect a multimeter to the output binding posts and set the multimeter to mV scale.
2. Adjust trimpot RV101 in order to reach 0mV. It is easier to turn the trimpot ½ turn at a time, and let
DC offset stabilize in order to get an accurate reading.
3. A tolerance of ± 1mV is acceptable.
PRO-SVR_LEGACY
– mV ) ÷ 2) + mV
R120 R122 R120
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