Sony TC-WE425 Service Manual page 12

Bias Consumption Current Adjustment
This adjustment should be performed when replacing the head assy
or the bias oscillator transformer (T131, T231).
Procedure:
blank tape
CS-413
set
LINE IN
no signal
1. Connect the digital voltmeter to test point TP431.
2. Set RV131 (L-CH), RV231 (R-CH) to mechanical center.
3. Set to FWD record mode.
4. Adjust T131 (L-CH), T231 (R-CH) so that the digital voltmeter
reading becomes minimum.
Adjustment Value: Maximum 220 mV
Adjustment Location: MAIN board (See page 13.)
Record Bias Adjustment
Setting:
REC LEVEL control : standard record position (See page 10.)
Procedure:
1. Record Mode
AF OSC
attenuator
600 Ω
LINE IN
1) 315 Hz
2) 10 kHz
2. Playback Mode
recorded
portion
set
Confirm that the 10 kHz playback output is 0 ± 0.5 dB relative to
the 315 Hz output. If necessary, adjust RV131 (L-CH), RV231 (R-
CH) and repeat the steps given above.
Adjustment Location: MAIN board (See page 13.)
DECK B
digital
voltmeter
+
–
R-CH L-CH
TP431
1 2 3
DECK B
blank tape
10 k Ω
CS-123
set
38.8 mV (–26 dB)
level meter
47 k Ω
+
–
LINE OUT
Record Level Adjustment
Setting:
REC LEVEL control : standard record position (See page 10.)
Procedure:
1. Record Mode
AF OSC
attenuator
2. Playback Mode
recorded
portion
Confirm playback the tape recorded become adjustment level as
follows.
If necessary, adjust RV161 (L-CH), RV261 (R-CH) and repeat the
steps 1 and 2.
Adjustment Value:
LINE OUT level : –26 ± 0.5 dB (36.7 to 41.1 mV)
Adjustment Location: MAIN board (See page 13.)
– 12 –
DECK B
blank tape
CS-123
10 k Ω
set
600 Ω
LINE IN
315 Hz, 38.8 mV (–26 dB)
level meter
47 k Ω
+
set
–
LINE OUT