Read Sony HCD-H991AV / MHC-991AV / MHC-G99AV Service Manual online
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2. Turn the adjustment screw and check output peaks. If the peaks
do not match for L-CH and R-CH, turn the adjustment screw so
that outputs match within 1 dB of peak.
that outputs match within 1 dB of peak.
L-CH
peak
peak
R-CH
peak
peak
screw
position
position
output
level
level
within
1dB
1dB
within 1dB
L-CH
peak
peak
screw
position
position
R-CH
peak
peak
3. Mode: Playback
Tape Speed Adjustment (Deck A)
Note: Start the Tape Speed adjustment as below after setting the
test mode.
The tape speed can be changed with the HIGH SPEED
DUBBING button during the test mode.
The tape speed can be changed with the HIGH SPEED
DUBBING button during the test mode.
Method :
1. Turn the power switch on.
2. Press the DISPLAY/DEMO button, MENU 1 button and
1. Turn the power switch on.
2. Press the DISPLAY/DEMO button, MENU 1 button and
TUNER/BAND button simultaneously.
Procedure :
Mode: Playback
Mode: Playback
frequency counter
+
–
–
main board
CN403 Pin 3 (L-CH)
CN403 Pin 3 (L-CH)
Pin 1 (R-CH)
test tape WS-48B
(3kHz, 0dB)
(3kHz, 0dB)
1. Insert the WS-48B into the deck A to playback.
2. Press the HIGH SPEED DUBBING button. Then at HIGH
2. Press the HIGH SPEED DUBBING button. Then at HIGH
SPEED mode.
3. Adjust the RV652 on the MD board so that the frequency
counter reading becomes 6,000
±
30 Hz.
4. Press the HIGH SPEED DUBBING button again to be set the
NORMAL SPEED mode.
5. Set to the playback mode.
6. Adjust the RV651 on the MD board so that the frequency
6. Adjust the RV651 on the MD board so that the frequency
counter reading becomes 3,000
±
15 Hz.
Frequency difference between deck A and deck B the beginning
of the tape should be within
of the tape should be within
±
1.5%.
Adjustment Location: MD board
Playback Level Adjustment (Deck A, Deck B)
Procedure:
Mode: Playback
set
main board
CN403 Pin 3 (L-CH)
CN403 Pin 3 (L-CH)
Pin 1 (R-CH)
level meter
Deck A is RV311 (L-CH) and RV411 (R-CH), deck B is RV301
(L-CH) and RV401 (R-CH)
so that adjustment within the following adjustment level.
(L-CH) and RV401 (R-CH)
so that adjustment within the following adjustment level.
Adjustment level:
CN403 playback level: 301.5 to 338.3 mV (–8.2 to –7.2 dB)
level difference between the channels: within
level difference between the channels: within
±
0.5 dB
Adjustment Location: MD board
test tape P-4-L300
(315Hz, 0dB)
(315Hz, 0dB)
4. After the adjustments, apply suitable locking compound to the
parts adjusted.
Adjustment Location: Playback Head (Deck A)
Record/Playback/Erase Head (Deck B)
Waveform of oscilloscope
45˚
90˚
135˚
180˚
wrong
good
in phase
main board
CN403
Pin 3 (L-CH)
CN403
Pin 3 (L-CH)
Pin 2 (GND)
L
R
oscilloscope
Pin 1 (R-CH)
test tape
P-4-A100
(10kHz, –10dB)
P-4-A100
(10kHz, –10dB)
set
Adjustment screw
FWD side
REV side
set
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