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– 9 –

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.

4. After the adjustments, apply suitable locking compound to the

parts adjusted.

Procedure :
Mode : Playback

3. Mode : Playback

1. Insert the WS-48B into the deck, and playback.
2. Adjust the VR770/RELAY board so that the frequency counter

reading becomes 3000 ± 90 Hz.

Adjustment Location : RELAY board

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

Procedure :
Mode : Playback

oscilloscope

MD OUT (JK301)

set

MD OUT (JK301)

test tape
P-4-A100
(10kHz, –10dB)

L

R

Waveform of oscilloscope

good

wrong

in phase

45 

°

90 

°

135 

°

180 

°

L-CH
peak

R-CH
peak

screw
position

output
level

within
1dB

L-CH
peak

R-CH
peak

screw
position

within 1dB

+
–

MD OUT (JK301)

set

frequency counter

test tape
WS-48B
(3kHz, 0dB)

 FWD side

REV side

Adjustment screw

level meter

MD OUT (JK301)

set

test tape
P-4-L300
(315Hz, 0dB)

Deck is VR703 (L-CH) and VR704 (R-CH)
so that adjustment within the following adjustment level.

Playback level: 301.5 to 338.3 mV (–8.2 to –7.2 dB) level dif-
ference between the channels: within ±0.5 dB

Adjustment Location : TAPE PREAMP board

– 10 –

2. Mode : Playback

2. Mode: Playback

Confirm playback the signal recorded in step 1 become adjustment
level as follows.
If these levels do not adjustment level, adjustment the VR701 (L-
CH) and VR702 (R-CH) on the TAPE PREAMP board to repeat
steps 1 and 2.

Adjustment level : Playback output of 10kHz level diffrence

against 315Hz reference should be ±0.5 dB.

Adjustment Location : TAPE PREAMP board

Procedure :
1. Mode: Record

Confirm playback the signal recorded in step 1 become adjustment
level as follows.
If these levels do not adjustment level, adjustment the VR705 (L-
CH) and VR706 (R-CH) on the TAPE PREAMP board to repeat
steps 1 and 2.

Adjustment level :
Playback level : 47.2 to 53.0 mV (–24.3 to –23.3 dB)
Adjustment Location : TAPE PREAMP board

[RELAY BOARD] (Component Side)

Procedure :
1. Mode : Record

level meter

MD OUT (JK301)

set

recorded
position

AF OSC

attenuator

600

Ω

set

MD IN (JK301)
1) 315Hz
2) 10kHz

blank tape
CS-123

50 mV (–23.8 dB)

}

AF OSC

attenuator

600

Ω

set

MD IN (JK301)
315Hz 50 mV (–23.8 dB)

blank tape
CS-123

VR770

level meter

MD OUT (JK301)

set

recorded
position

VR704

VR703

VR706

VR705

VR701

VR702

IC703

1

21

22

42

[TAPE PREAMP BOARD] (Component Side)

– 11 –

Procedure:
1. Connect oscilloscope to test point TP (RF).
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Adjust RV101 so that the waveform is clear.

(Clear RF signal waveform means that the shape “

◊

” can be

clearly distinguished at the center of the waveform.)

5. After adjustment, check the RF signal level.

• RF signal

VOLT/DIV: 200 mV
TIME/DIV: 500 nS

Procedure :
1. Connect oscilloscope to test point TP (FEO).
2. Connect between test point TP (FOK) and Ground by lead wire.
3. Turn Power switch on.
4. Put disc (YEDS-18) in and turned Power switch on again and

actuate the focus search. (actuate the focus search when disc
table is moving in and out.)

5. Check the oscilloscope waveform (S-curve) is symmetrical be-

tween A and B. And confirm peak to peak level within 2.4 ± 0.7
Vp-p.

S-curve waveform

6. After check, remove the lead wire connected in step 2.

 • Try to measure several times to make sure than the ratio of

A : B or B : A is more than 10 : 7.

• Take sweep time as long as possible and light up the bright-

ness to obtain best waveform.

Procedure :
1. Connect oscilloscope to test point TP (RF) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Confirm that oscilloscope waveform is clear and check RF sig-

nal level is correct or not.

Clear RF signal waveform means that the shape “

◊

” can be

clearly distinguished at the center of the waveform.

RF signal waveform

1. CD Block is basically designed to operate without adjustment.

Therefore, check each item in order given.

2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10M

Ω

 impedance.

4. Clean the object lens by an applicator with lens cleaning liquid

when the signal level is low than specified value with the fol-
lowing checks.

5. Adjust the focus bias adjustment when optical block is replaced.

–

+

oscilloscope

 BD board

TP (RF)
TP (VC)

level : 1.3 

±

 0.3 Vp-p

–

+

oscilloscope

 BD board

TP (FEO)
TP (VC)

symmetry

A

B

within 2.4 

±

 0.7 Vp-p

–

+

oscilloscope

 BD board

TP (RF)
TP (VC)

level : 1.3 

±

 0.3 Vp-p

VOLT/DIV : 200 mV
TIME/DIV : 500 nS

– 12 –

Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Turn Power switch on.
3. Put disc (YEDS-18) in to play the number five track.
4. Press the “

P (Pause)” button. (Becomes the 1 track jump mode)

5. Confirm that the oscilloscope waveform is symmetrical on the

top and bottom in relation to 0Vdc, and check this level.

1 track jump waveform

Specified level: •                     x 100 = less than ± 7%

• A + B = 300 ± 100 mVp-p

6. Remove the lead wire connected in step 1.

This gain has a margin, so even if it is slightly off.
There is no problem.
Therfore, do not perform this adjustment.
Please note that it should be fixed to mechanical center position
when you moved and do not know original position.

A – B

2 (A + B)

[BD BOARD] — Component Side —

–

+

oscilloscope

 BD board

TP (TE)
TP (VC)

A

B

0V

LEVEL : 300 

±

 100 mVp-p

RF

RV101

RV103

TEO

VC

FEO

RV102

TEI

FEI

FOK

IC101

IC104

GND

PCK

IC102