Onkyo TX-8255 Service Manual page 35

ADJUSTMENT PROCEDURE
IDLING CURRENT ADJUSTMENT
[When]
1. Exchange Power transistor (Q521 - Q524).
2. Exchange Amplifier PC board (NAAF-8886).
[Procedure]
<Note> No load and No signal
Refer to <Fig-1> for the adjustment points and the test points.
1. Before idling adjustment, turn the trimming resistors fully to counter clockwise.
2. Connect the dc voltmeter to test points, using two 100 ohm resistors between the poles of the jig terminal and
the DC voltmeter terminals.
DC voltmeter
3. Connect the AC power cord to a wall outlet.
4. Press ON/STANDBY button to turn the power on.
5. Adjust the trimming resistors as the following procedure immediately after power on.
Channel Adjustment points
Left R587 R587
Right R588 R588
6. Wait for 4 - 6 minutes. (Heat running)
7. Re-adjust the trimming resistors as the following procedure.
Channel
Left and Right
Idling currents are stabilized in about 10 minutes after power on.
8. Disconnect the DC voltmeter.
9. Press ON/STANDBY button to turn the power off.
10. Disconnect the AC power cord.
<Fig-1>
100 ohms
Jig terminal
(1/4 watt)
Test points
P511 P511
P512 P512
Measured value
In case below 4.4 mV
In case 4.5 - 5.5 mV
In case over 5.6 mV
Amplifier PC board
(NAAF-8886)
RIGHT
P512 R588
Right ch
Test point
ID+
ID-
Adjustment value
2.5 mV 2.5 mV
Spec.
Adjustment value
( In a stable state)
4.5 mV 4.5 mV
Leave it as it is Leave it as it is 6 +/- 2 mV
5.5 mV 5.5 mV
LEFT
R587 P511
Left ch
TX-8255
Front side