HCD-VX90AV, MHC-VX90AV - Sony Audio Service Manual (repair manual). Page 14

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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

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 TYPE 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

W.RMS (JIS) less than 0.3%
(test tape: WS-48B)

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

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)