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21

3. Mode: Playback

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

parts adjusted.

Adjustment Location: Playback Head (Deck A)

Record/Playback/Erase Head (Deck B)

set

test tape
P-4-A100
(10 kHz, – 10 dB)

R-CH

oscilloscope

L-CH

R-CH

V

H

waveform of oscilloscope

in phase 45

°

90

°

135

°

180

°

good

wrong

AMP board
SPEAKER terminal (JK441)
L-CH

Mode: Playback

1. Insert the WS-48B into the deck.
2. Press the  H  button on the deck.
3. Confirm that the frequency counter reads 3,000 ± 90 Hz.

Sample value of Wow and Flutter: 0.3% or less W.RMS (JIS)

(WS-48B)

+
–

set

test tape
WS-48B 
(3 kHz, 0 dB)

AMP board
SPEAKER terminal (JK441)
L-CH, R-CH

frequency counter

reverse

forward

22

       RFDC signal waveform

Checking Location: BD81A board (Side B)

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

Ω

 impedance.

3. Clean the object lens by an applicator with neutral detergent when the

signal level is low than specified value with the following checks.

Procedure:
1.

Connect an oscilloscope to test point  (RFDCO) and  TP (VC)
on the BD81A board.

2.

Turn the power on.

3.

Put the disc (YEDS-18) in to playback the number five track.

4.

Confirm that oscilloscope waveform is clear and check RFDC
signal level is correct or not.

A clear RFDC signal waveform means that the shape “

◊

” can be

clearly distinguished at the center of the waveform.

+
–

BD81A board

TP (RFDCO)

TP (VC)

oscilloscope

VOLT/DIV: 200 mV
TIME/DIV: 500 ns 

level: 0.6 

±

 0.15 Vp-p

Procedure:
1.

Connect an oscilloscope to test point TP (RFACO) and  TP 
(VC) on the BD81A board.

2.

Turn the power on.

3.

Put the disc (YEDS-18) in to playback the number five track.

4.

Confirm that oscilloscope waveform is clear and check RFAC
signal level is correct or not.

A clear RFAC signal waveform means that the shape “

◊

” can be

clearly distinguished at the center of the waveform.

       RFAC signal waveform

Checking Location: BD81A board (Side B)

+
–

BD81A board

TP (RFACO)

TP (VC)

oscilloscope

VOLT/DIV: 200 mV
TIME/DIV: 500 ns 

level: 1.0 

±

 0.4 Vp-p

Procedure:
1.

Connect an oscilloscope to test point TP (FEO) and TP (VC)
on the BD81A board.

2.

Turn the power on.

3.

Put the disc (YEDS-18) in and press the         button and 
actuate the focus search. (actuate the focus search when
disc table is moving in and out)

4.

Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 2 

±

 1

Vp-p.

S-curve waveform

• 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

brightness to obtain best waveform.

Checking Location: BD81A board (Side B)

+
–

BD81A board

TP (FEO)

TP (VC)

oscilloscope

A

B

symmetry

within 2 

±

 1 Vp-p

H

23

Checking Location: BD81A board (Side B)

+
–

BD81A board

TP (TEO)

TP (VC)

oscilloscope

Traverse Waveform

0V

B

level: 1.0 

±

 0.5 Vp-p

Center of 
the waveform

A (DC 

voltage)

Traverse Waveform

0V

Tracking servo

Sled servo

ON

C (DC 
voltage)

Tracking servo

Sled servo

OFF

6.

Press the

button. (The tracking servo and sledding

servo are turned ON)

7. To exit from this mode, turn the power off.

Notes:

• Always move the optical pick-up to most inside track when

exiting from this mode. Otherwise, a disc will not be unloaded.

• Do not run the sled motor excessively, otherwise the gear can

be chipped.

Procedure:
1.

Connect an oscilloscpe to test point TP (TEO) and TP (VC) on
the BD81A board.

2.

Press three buttons

x

3.

Put the disc (YEDS-18) in to playback the number five track.

4.

Press the             button. If it plays, press the

H

 

(The tracking servo and the sledding servo are turned OFF)

5.

Check the level B of the oscilliscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than 

±

 10%

H

H

PLAY MODE/TUNING MODE

and

simulfaneously enter the CD test mode. 

Z

button again.

,

,

(SideB)

BD81A BOARD

TP

(RFACO)

TP

(VC)

TP

(FEO)

TP

(RFDCO)

TP

(TEO)

25

25

HCD-RG444

Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted.  (p: pF)

50 WV or less are not indicated except for electrolytics
and tantalums.

• All resistors are in 

Ω

 and 

1

/

4

 

W or less unless otherwise

specified.

•

f

: internal component.

•

C

: panel designation.

• X

: parts extracted from the component side.

• b

: Pattern from the side which enables seeing.

• Indication of transistor.

•

A

: B+ Line.

•

B

: B– Line.

•

H

: adjustment for repair.

• Voltages and waveforms are dc with respect to ground

under no-signal (detuned) conditions.

• Voltages are taken with a VOM (Input impedance 10 M

Ω

).

Voltage variations may be noted due to normal produc-
tion tolerances.
no mark : FM
(

 

) :  CD STOP

• Waveforms are taken with a oscilloscope.

Voltage variations may be noted due to normal produc-
tion tolerances.

• Circled numbers refer to waveforms.

• Signal path.

F

: TUNER

E

: PB (DECK A)

d

: PB (DECK B)

G

: REC (DECK B)

J

: CD

f

: AUDIO

C

B

These are omitted.

E

Q

B

These are omitted.

C

E

Q

Caution:
Pattern face side:

Parts on the pattern face side seen from

(SIDE A)

the pattern face are indicated.

Parts face side:

Parts on the parts face side seen from

(SIDE B)

the parts face are indicated.

– PANEL BOARD –

SUB-TRANS board

VIDEO OUT board

GAME JACK board

PANEL board

6 STREAM LED board

H/P JACK board

TRANSLATION  board

MAIN board

REM board

MOTOR (LD) board

SW board

SENSOR board

BD81A board

MOTOR (TB) board

DRIVER board

CONNECT board

SUB-WOOFER board

AMP board

TRANS board

Note: The components identified by mark 

0

 or dotted

line with mark 

0

 are critical for safety.

Replace only with part number specified.