XM-1004GX
8
Bias Adjustment
Note :
The Bias adjustment should be performed only if any of
Q108 and Q110 for VR101, Q208 and Q210 for VR201,
Q308 and Q310 for VR301, and Q408 and Q410 for VR401
are replaced.
Setting :
Procedure:
1. Rotate variable resistors VR101 (FRONT L-CH), VR201
(FRONT R-CH), VR301 (REAR L-CH) and VR401 (REAR R-
CH) full counterclockwise as seen from the pattern side to
minimize the bias current.
2. The input signal is with no signal.
3. Connect the stabilized power supply between B+ and REM
terminals and gradually increase the voltage to 14.4 V while
checking for any abnormal current.
4. Adjust VR101 (FRONT L-CH), VR201 (FRONT R-CH), VR301
(REAR L-CH) and VR401 (REAR R-CH) so that the digital
voltmeter connected between the respective test points reads
4.5±1 mV.
SECTION 3
ELECTRICAL ADJUSTMENT
– AMP BOARD (COMPONENT SIDE) –
VR101
BIAS ADJUSTMENT
(FRONT L-CH)
VR201
BIAS ADJUSTMENT
(FRONT R-CH)
VR301
BIAS ADJUSTMENT
(REAR L-CH)
VR401
BIAS ADJUSTMENT
(REAR R-CH)
+
_
Stabilized
Power supply
Digital
Voltmeter
B+,REM terminals
set
GND terminal
test points
Adjustment Location :
Test Point Location :
– AMP BOARD (CONDUCTOR SIDE) –
TP302
TP402
TP101
TP102
TP201
TP202
TP401
TP301
RV Ref. No.
Test points
VR101
TP101 and TP102
VR201
TP201 and TP202
VR301
TP301 and TP302
VR401
TP401 and TP402
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