![background image](http://html.mh-extra.com/html/sony/mhc-grx90av/mhc-grx90av_service-manual_1330026016.webp)
– 15 –
4. After the adjustments, apply suitable locking compound to the
parts adjusted.
Adjustment Location: Playback Head (Deck A)
Record/Playback/Erase Head (Deck B)
3. Mode: Playback
Tape Speed Adjustment (Deck A)
Note: Set the test mode using the following method and begin tape
speed adjustment.
In the test mode, the speed will switch to double speed or
normal speed each time the HI-DUB button is pressed.
Procedure:
With the power turned ON, press the
p
button, ENTER/NEXT
button, and DISC 3 button simultaneously.
(The “CD TABLE INDICATOR” on the fluorescent display tube
will blink while in the test mode.)
To exit the test mode, press the
1/u
button.
1. Insert the WS-48B into deck B.
2. Press the
(
button of deck B.
3. Press the HI-DUB button and play the tape at double speed.
4. Adjust RV1001 of the LEAF SW board so that the reading of
the frequency counter becomes 6000 ± 180 Hz.
5. Press the HI-DUB button and play the tape at normal speed.
6. Adjust RV1002 of the LEAF SW board so that the reading of
the frequency counter becomes 3000 ± 90 Hz.
Adjustment Location: LEAF SW board
Sample Value of Wow and flutter
W.RMS (JIS) less than 0.3%
(test tape: WS-48B)
Playback Level Adjustment (Deck A, Deck B)
Procedure:
Mode: Playback
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.
Adjustment level:
CN301 playback level: 301.5 to 338.3 mV (–8.2 to –7.2 dB)
level difference between the channels: within ± 0.5 dB
Adjustment Location: AUDIO board
Adjustment Location
[LEAF SW BOARD]
test tape
P-4-A100
(10kHz, –10dB)
oscilloscope
set
Waveform of oscilloscope
in phase
45
°
90
°
135
°
180
°
good
wrong
MD OUT
Reverse
Foward
test tape
P-4-L300
(315Hz, 0dB)
level meter
set
MD OUT
RV1002
RV1001
RV1002(Normal Speed)
RV1001(High Speed)