Sony HCD-GN88D Service Manual page 21

REC BIAS ADJUSTMENT DECK B
Procedure:
In the MC test mode, the "REC memory mode" is convenient for
this adjustment. In the "REC memory mode" , when the REC starts
the input signal FUNCTION is switched to VIDEO automatically.
When the REC stops, the tape returns near to the recording start
position.
1. Press MD (VIDEO) button to select VIDEO. (This step is not
necessary if the above test mode has already been set)
2. Insert a tape into deck B.
[REC PAUSE/START]
3. After press
START]
button, then recording start.
4. Mode: Record
MAIN board
MD/VIDEO (AUDIO) IN (J117)

1) 315 Hz

2) 10 kHz

AF OSC
600 Ω
attenuator
5. Mode: Playback
MAIN board
CN301
recorded
Pin 1 (L-CH)
portion
Pin 3 (R-CH)
set
MAIN board
CN301 Pin 2 (GND)
6. Confirm the playback signal recorded in step 3 becomes
adjustable level as follows.
If these levels are not adjustable level, adjust the RV304 (L-
CH) and RV354 (R-CH) on the MAIN board to repeat steps 4
and 5.
Adjustable level: Playback output of 315 Hz to playback output
of 10 kHz: ±1.0 dB
Adjustment Location: MAIN board
REC LEVEL ADJUSTMENT DECK B
Procedure:
In the MC test mode, the "REC memory mode" is convenient for
this adjustment. In the "REC memory mode" , when the REC starts
the input signal FUNCTION is switched to VIDEO automatically.
When the REC stops, the tape returns near to the recording start
position.
1. Press MD (VIDEO) button to select VIDEO. (This step is not
necessary if the above test mode has already been set)
2. Insert a tape into deck B.
[REC PAUSE/START]
3. After press
START]
button, then recording start.
[REC PAUSE/
button, press
50 mV (–23.8 dB)
blank tape
CN-123
set
level meter
+
–
[REC PAUSE/
button, press
4. Mode: Record
MAIN board
MD/VIDEO (AUDIO) IN (J117)
315 Hz, 50 mV (–23.8 dB)
AF OSC
600 Ω
attenuator
5. Mode: Playback
MAIN board
CN301
recorded
Pin 1 (L-CH)
portion
Pin 3 (R-CH)
set
MAIN board
CN301 Pin 2 (GND)
6. Confirm the play back signal recorded in step 3 becomes
adjustable level as follows.
If these levels are not adjustable level, adjust the RV301 (L-
CH) and RV351 (R-CH) on the MAIN board to repeat steps 4
and 5.
Adjustable level:
CN301 PB level: 47.2 to 53.0 mV (–24.3 to –23.3 dB)
Adjustment Location: MAIN board
– MAIN BOARD (Component Side) –
HCD-GN88D
blank tape
CS-123
set
level meter
+
–
REC LEVEL
ADJUSTMENT
3 1
RV301
CN301
(L-CH)
(R-CH)
RV351
IC301
RV304
RV354
(L-CH) (R-CH)
REC BIAS ADJUSTMENT
21