JVC A-X2 - Power Amplifier Idling Current Adjustment; Printed Circuit Board Assy and Parts List; TXX-241 A Power Amp., Volume Control

7. Power Amplifier Idling Current Adjustment Procedure
OO
Left Channel
R627
(—) (+)
Before turning on the power, turn the semi-fixed resistors
<R627 for L channel and R628 for R channel> of the power
amplifier circuit board fully counterclockwise.
Adjust the semi-fixed resistors (R627 and R628) so that the
voltage at the following test points of the power amplifier
circuit board is within a range of 10 mV — 14 mV after the
power is turned on.
L channle: Measure the voltage between test point (A) (emitter
of X619) and output at the test point ®).
R channel: Measure the voltage between test point © (emitter
of X620) and output at the test point ©.
© oo
Right Channel
R628
Fig. 8
3. Readjust resistors R627 and R628 about 5 minutes after the
power is turned on (the heat sink temperature must be suf-
ficiently high) so that the voltage at the test points becomes
12 mV.
Confirm that the voltage does not vary when the heat sink
temperature increases further.
Note: Be sure to perform the measurement with the probes
and cabinet of the measuring equipment separated
from the grounding terminals of A-X2 or of other
measuring equipment.
8. Printed Circuit Board Ass’y and Parts List
8-(1) TXX-241A Power Amp., Volume Control & Other Functions Split
A-X2
P.C. Board Ass’y
No. 2507
Fig. 9
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