Sony TC-WE635 Service Manual page 13

Bias Consumption Current Adjustment
This adjustment should be performed when replacing the head assy
or the bias oscillator transformer (T131, T141),(T231, T241).
Setting:
REC LEVEL knob : standard recording position (See page 11.)
Procedure:
blank tape
CS-413
set
LINE IN
no signal
1. Connect the digital voltmeter to test point TP331 ( DECK A)
and TP441 (DECK B).
2. Set DECK A: RV131 (L-CH), RV231 (R-CH) and DECK B:
RV141 (L-CH), RV241 (R-CH) to mechanical center.
3. Press the · button to playback.
4. Adjust DECK A: T131 (L-CH), T231 (R-CH) and DECK B:
T141 (L-CH), T241 (R-CH) so that the digital voltmeter
reading becomes minimum.
Adjustment Value: Maximum 220 mV
Adjustment Location: MAIN board (See page 14.)
Record Bias Adjustment
Setting:
REC LEVEL knob : standard record position (See page 11.)
Procedure:
1. Set to test mode (See page 11.)
2. Insert a tape into deck B, press the REC r button and then
press the · button to start recording.
AF OSC
10 k Ω
attenuator
600 Ω
LINE IN
1) 315 Hz
2) 10 kHz
3. Record Mode
recorded
portion
set
4. Playback Mode
5. Confirm playback the signal recorded in step 2 become adjust-
ment level as follows.
If the selevels do not adjustment level, adjust DECK A: RV131
(L-CH), RV231 (R-CH) and DECK B: RV141 (L-CH), RV241
(R-CH) to repeat steps 3 and 4.
DECK A DECK B
digital
voltmeter
R-CH L-CH
TP331 (DECK A)
1 2 3
TP441 (DECK B)
DECK A DECK B
blank tape
CS-123
set
50 mV (–23.8 dB)
level meter
47 k Ω
LINE OUT
Adjustment level:
The palyback output of 10 kHz level difference against 315 Hz ref-
erence should be ± 0.5 dB.
Adjustment Location: MAIN board (See page 14.)
Record Level Adjustment
Setting:
REC LEVEL knob : standard record position (See page 11.)
Procedure:
1. Set to test mode (See page 11.)
2. Insert a tspe into deck B, press the REC r button and then
press the · button to start recording.
3. Record Mode
AF OSC
attenuator
4. Playback Mode
recorded
portion
5. Confirm playback the signal recorded in step 2 become adjust-
ment level as follows.
If the selevels do not adjustment level, adjust the RV101 (L-CH)
and RV201 (R-CH) to repeat steps 3 and 4.
Adjustment Value:
LINE OUT level : –23.8 ± 0.5 dB (47.2 to 53.0 mV)
Adjustment Location: MAIN board (See page 14.)
– 13 –
DECK A DECK B
blank tape
CS-123
10 k Ω
set
600 Ω
LINE IN
315 Hz, 50 mV (–23.8 dB)
level meter
47 k Ω
set
LINE OUT