Adjustment - Pioneer A-A6-S Service Manual

1

6. ADJUSTMENT

6.1 Idle Current and DC offset Adjustment
A
1. Idle Current Adjustment
• Measurement Points:
Adjustment
•
• Procedure
B
• Adjustment Point and Measurement Points.... see fig1.
2. DC Offset Adjustment
• Measurement Points:
Adjustment
•
• Procedure
C
• Adjustment Point and Measurement Points.... see fig1.
+
8 Ω Speaker dummy connection.
D
DC offset RV703
VR: VR701
E
I
Caution when transistors (Q713, Q714, Q739 and Q746) are replaced
F
Please cover the leads of the transistors at Silicon bond for the variation prevention
of DC Offset when you have exchanged transistors.
54
1
2
AMP Lch Assy : R729
AMP Rch Assy : R774
Points: AMP Lch Assy : VR702
AMP Rch Assy : VR703
1 Turn on the power
2 Connect a digital voltmeter to both ends of resistor of the measurement point.
(70 mV of AMP Lch: R729 and AMP Rch: R774).
3 Perform aging for more than five minute.
4 Slowly turn the adjustment VR clockwise so that the voltage becomes in the
readjustment of 60 mV
AMP Lch Assy : SP terminal
AMP Rch Assy : SP terminal
Points: AMP Lch Assy : VR701
AMP Rch Assy : VR704
1 The voltage of SP terminal is adjusted to 0 ± 10 mV.
(8 Ω Speaker dummy connection)
Idle -TP
R729
Idle current RV703
VR: VR702
AMP Lch Assy
2
3
+
Refer to below
in exchange
Q714
Q713
Q746
Q739
Idle current
VR: VR703
J
[fig 1.]
A-A9-J
3
4
8 Ω Speaker dummy connection.
DC offset
VR: VR704
Idle -TP
R774
AMP Rch Assy
4