DOWNLOAD Sony HCD-XB4K / LBT-XB4K / LBT-XB4KS Service Manual ↓ Size: 1.8 MB | Pages: 77 in PDF or view online for FREE

– 33 –

1. Insert the WS-48B into the deck A and the blank tape into the

deck B.

2. Press the REC button and

· button on the deck B.  Then

the deck B is at recording mode.

3. Set the deck A to playback mode.
4. Keep pressing the H. SPEED DUBB button in playback mode.

Then at HIGH speed mode.

5. Adjust RV652 on the AUDIO board do that frequency counter

reads 6,000 ± 90 Hz.

6. Take off the H. SPEED DUBB button.

Then at NORMAL speed mode.

7. Adjust RV651 on the AUDIO  board so that frequency counter

reads 3,000 ± 90 Hz.

8. Frequency difference between deck  A and deck B the begin-

ning of the tape should be within ± 1.5%.

Adjustment Location:  AUDIO board

Sample Value of Wow and flutter: 0.3% or less W.RMS

(WS-48B)

Procedure:
Mode:  Playback (FWD)

Screw
position

L-CH
peak

within
1dB

output
level

L-CH
peak

R-CH
peak

within
1dB

Screw
position

R-CH
peak

3. Mode:  Playback (FWD)

4. Repeat steps 1 to 3 in playback (REV) mode.
5. After the adjustments, apply suitable locking compound to the

pats adjusted.

Adjustment Location:  Record/Playback Head (Deck A and B)

and MAIN board.

reverse

forward

Note: Start the Tape Speed adjustment as below after setting to

the test mode.
In the test mode, the tape speed is high during pressing the
  H. SPEED DUBB button.

Procedure:
1. Turn the power switch on.
2. Press the SPECTRUM ANALYZER button, ENTER button

and   EFFECT button simultaneously.
To exit from the test mode, press the POWER button.

Mode:  Playback (FWD)

MAIN
board
CN207
set

test tape
P-4-A100
(10kHz, –10dB)

pin 

3

oscilloscope

L-CH

R-CH

V

H

waveform of oscilloscope

in phase 45

°

90

°

135

°

180

°

good

wrong

pin 

2

pin 

1

L

R

1. Mode:  Playback (FWD)
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 1dB of peak.

+
–

set

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

MAIN board
CN207 (Pin 

1

: L-CH)

(Pin 

3

: 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 adjustment
level as follows.
Adjustment Level:

CN207 PB 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 and MAIN boards

+
–

set

test tape
WS-48B 
(3 kHz, 0 dB)

MAIN board
CN207 (Pin 

1

 : L-CH)

(Pin 

3

 : R-CH)

frequency counter

– 34 –

Confirm playback the signal recorded in step 1 become adjustable
limits as follows.
If these levels do not adjustable limits, adjustment the RV341 (L-
CH) and RV441 (R-CH) on the AUDIO board to repeat steps 1 and
2.
Adjustable limits: Playback output of 315 Hz to playback output

of 10kHz:  0±0.5 dB

Adjustment Location: AUDIO and MAIN boards

Procedure:
1. Mode:  Record

2. Mode:  Playback

attenuator

set

Pin 

6

 (L-CH) of IC1501 on the MAIN board.

Pin 

#¶

 (R-CH) of IC1501 on the MAIN board.

1) 315 Hz
2) 10 kHz

50 mV (–23.8 dB)







Pin 

2

 (GND) of ICN207 on the MAIN board.

600 

Ω

blank tape
CN-123

AF OSC

[MAIN  BOARD] (Component Side)

Procedure:
1. Mode:  Record

RV1501

IC1501

CN205

CN207

RV1551

Record Level
Adjustment

IC301

IC201

1

3

Record Bias Current

Adjustment

Tape Speed Adjustment

(NORMAL)

RV651

®

(HIGH)

RV652

®

RV311

L 

®

RV411

R 

®

Playback Level

Adjustment

RV441 RV341

RV301

®

L

RV401

®

R

R

L

– DECK B –

– DECK A –











Playback Level
Adjustment

    

































[AUDIO  BOARD]  (Conductor Side)

2. Mode:  Playback

+
–

set

recorded
portion

MAIN board
CN207 (Pin 

1

: L-CH)

(Pin 

3

: R-CH)

level meter

Confirm playback the signal recorded in step 1 become adjustable
limits as follows.
If these levels do not adjustable limits, adjustment the RV1501
(L-CH) and RV1551 (R-CH) on the MAIN board to repeat steps 1
and 2.
Adjustable limits:

CN207 PB level:  47.3 to 53.1 mV (–24.3 to –23.3 dB)

Adjustment Location:  MAIN board

+
–

set

recorded
portion

MAIN board
CN207 (Pin 

1

: L-CH)

(Pin 

3

: R-CH)

level meter

set

Pin 

6

  (L-CH) of IC1501 on the MAIN board.

Pin 

#¶

  (R-CH) of IC1501 on the MAIN board.

315 Hz, 50 mV (–23.8 dB)

blank tape
CS-123

Pin 

2

  (GND) of CN207 on the MAIN board.

600 

Ω

attenuator

AF OSC

– 35 –

TUNER  SECTION

0dB=1µV

Note: As a front-end (FE1) is difficult to repair if faulty, replace

it with new one.

(Except Thai model)

AM RF  SSG

loop antenna

set

loop antenna

(Supplied accessories)

60 cm

AM ANTENNA

terminal (TM1)

30% amplitude

modulation by

400 Hz signal

Field strength dB (

µ

V/m) =SSG output level dB (

µ

V/m) –26 dB.

Band:  AM
Procedure:
1. Set the output of SSG so that the input level of the set be-

comes 55 dB.

2. Tune the set to  999 kHz.
3. Adjust RV42 to the point (moment) when the TUNED indica-

tor will change from going off to going on.

Adjustment Location :  TCB board

Note:  This adjustment should be performed after the AM Tuned

Level Adjustment due to the same adjustment element.

[TCB BOARD]  (Component Side)

RV41

FM Tuned Level

Adjustment

IC2

RV42

AM Tuned

Level

Adjustment

TM1

FE1

Band:  FM
Procedure:
1. Supply a 25dBµ 98 MHz signal from the ANTENNA termi-

nal.

2. Tune the set to 98 MHz.
3. If the TUNED indicator does not light, adjust RV41 to the

point (moment) when the TUNED indicator will change from
going off to going on.

Adjustment Location:  TCB board

Carrier frequency   : 98 MHz
Modulation              : AUDIO 1 kH, 75 kHz
                                 deviation (100%)

FM ANTENNA terminal
(TM1) (75 

Ω

 open)

75 

Ω

 coaxial

set

FM RF stereo signal
generator

– 36 –

BD board

TP (FEO)
TP (VC)

oscilloscope

+
–

Procedure:
1. Connect oscilloscope to test point TP (FEO).
2. Connect between test point TP (FOK) and GND 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 3 ± 1
Vp-p.

S-curve waveform

  CD SECTION

Note:
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  impedance.
4. Clean the object lens by an applicator with neutral detergent

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

Note:  Clear RF signal waveform means that the shape “≈” can

be clearly distinguished at the center of the waveform.

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

level:
1.3 

±

 0.3 Vp-p

A

B

symmetry

within 3 

±

 1 Vp-p

Procedure:
1. Connect oscilloscope to test point TP (RF). (GND terminal :

VC)

2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Confirm that the shape “≈” can be clearly distinguished at the

center of the waveform and check the RF signal level.

BD board

TP (RF)
TP (VC)

oscilloscope

+
–

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

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.

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

level:
1.3 

±

 0.3 Vp-p

BD board

TP (FEO)
TP (VC)

oscilloscope

+
–