DOWNLOAD Sony BM-21 / BM-23 (serv.man3) Service Manual ↓ Size: 2.09 MB | Pages: 28 in PDF or view online for FREE

5

3

claw

2

two claws

qa

two claws

1

screw (M1.4)

AUDIO board

4

lever (lock)

9

lever (lock)

6

Remove the control panel block 

     assembly in the direction of the arrow.

7

control button assembly

qd

control panel 

      block assembly 

8

To attach the control panel block 

     assembly , align the three switch positions as shown.

qs

screw (M1.4)

control button assembly

5

control button assembly

0

claw

6

0

screw (M1.4 x 3)

1

 screw (M1.4 x 3)

4

battery case

5

three cabinet 

     upper cushions

8

Remove solder 

     from the seven points.

7

Remove soldering 

     from the five points.

6

harnesses

3

Remove the soldering.

qa

Remove the AUDIO board 

     in the direction of arrow.

9

 flexible board

     (CN101) (12core)

2

screw (1.7 x 2.5)

7

2

Set the holder panel 

      assembly to eject.

4

mechanism deck 

     (MB-23-101)

lock plate assembly

3

two screws (M1.4 

×

 3.0)

note : When attaching the mechanism deck,
          set the mechanism deck to stop and
          adjust the position of shaft-A and part
          

A

 of the lock plate assembly.

 

shaft-A

A

1

Remove the soldering.

4

holder panel assembly

1

While pressing the button (eject), insert

      the two claws of the holder panel assembly
      into the holes indicated by arrows 

A

.

2

Move the battery coil spring in the direction

      of the arrow and secure it with the screw.

3

two screws (M1.4 

×

 1.6)

A

A

claw

claw

8

FF

CQ-403A

more than 40 g

(more than 1.42 oz)

REW

CQ-403R

1. Clean the following parts with a denatured-alcohol-moistened

swab :

playback head

rubber belts

capstan

idlers

pinch roller

2. Demagnetize the playback head with a head demagnetizer.
3. Do not use a magnetized screwdriver for the adjustments.
4. The adjustments should be performed with the rated power

supply voltage (3V) unless otherwise noted.

FWD

CQ-102C

2.06 – 3.72 mN•m

(21 – 38 g•cm)

(0.30 – 0.52 oz•inch)

FWD

0.05 – 0.29 mN•m

Back Tension

(0.5 – 3 g•cm)

(0.01 – 0.04 oz•inch)

REV

CQ-102RC

2.06 – 3.72 mN•m

(21 – 38 g•cm)

(0.30 – 0.52 oz•inch)

REV

0.05 – 0.29 mN•m

Back Tension

(0.5 – 3 g•cm)

(0.01 – 0.04 oz•inch)

FF

CQ-201B

more than 60 g•cm

REW

(more than 0.84 oz•inch)

1. Power supply voltage : 3V

Switch position
TAPE SPEED Switch : 4.8 cm

1. Play back WS-48A (tape center portion) in FWD mode.

Adjust the RV601 so that the frequency counter reads 2,980

±

30 Hz.

2. Play back WS-48A (tape center portion) in REV mode.

Confirm that the reading of frequency counter is within 2.5 %
from the reading in step 1.

WS-48A

3 kHz, 0 db

Tape Speed Adjustment

J102

set

EAR

18 

Ω

test
WS-48A
(3 kHz, 0 dB)

frequency 
counter