Sony HCD-XGR90AV Service Manual page 19

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REC Bias Adjustment
Procedure:
1. Mode: Record
FUNCTION: VIDEO
MAIN board
MD(VIDEO) IN jack (J701)
L-CH, R-CH
1) 315 Hz
2) 10 kHz
AF OSC
attenuator
2. Mode: Playback
recorded
portion
set
3. Confirm playback the signal recorded in step 1 become speci-
fication values as follows.
If these values are out of specification values, adjust the RV321
(L-CH) and RV322 (R-CH) on the MAIN board to repeat
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L 13942296513
steps 1and 2.
Adjustment level: The playback output of 10kHz level difference
against 315 Hz reference should ±0.5 dB.
Adjustment Location: MAIN board
Adjustment Location: MAIN board
– MAIN BOARD (Component Side) –
RV392
TAPE SPEED
(HIGH)
RV301
REC LEVEL
(R-CH)
RV351
REC LEVEL
(L-CH)
RV321
REC BIAS
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(L-CH)
.
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DECK B


50 mV (– 23.8 dB)

blank tape
600 Ω CS-123
set
level meter
+
–
MAIN board
CN301 pin 1 (L-CH)
pin 3 (R-CH)
IC301
CN301
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REC Level Adjustment
Procedure:
1. Mode: Record
FUNCTION: VIDEO
MAIN board
MD (VIDEO) IN jack (J701)
L-CH, R-CH
315 Hz, 50 mV (– 23.8 dB)
AF OSC
attenuator
2. Mode: Playback
recorded
portion
3. Confirm playback the signal recorded in step 1 become speci-
fication values as follows.
If these values are out of specification values, adjust the RV351
(L-CH) and RV301 (R-CH) on the MAIN board to repeat steps
1 and 2.
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Specification values:
CN301 playback level: 47.2 to 53.0 mV (– 24.3 to – 23.3 dB)
RV391
TAPE SPEED
(NORMAL)
IC501
RV322
REC BIAS
(R-CH)
co
.
IN
OUT
MD (VIDEO)
HCD-XGR90AV
9 4 2 8
DECK B
600 Ω
set
level meter
+
set
–
MAIN board
CN301 pin 1 (L-CH)
pin 3 (R-CH)
0 5 8 2 9 9 4 2 8
m
9 9
blank tape
CS-123
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