Sony WMFS-421 Service manual

WM-FS421

SERVICE MANUAL

Ver 1.0 2001. 04

SPECIFICATIONS

• Frequency range

FM: 87.5 - 108 MHz AM: 530 - 1 710 kHz (North, Central and South America)

531 - 1 602 kHz (Other countries)

• Power requirements

3 V DC batteries R6 (size AA) × 2

• Dimensions (w/h/d)

Approx. 107.3 × 123.3 × 51.5 mm (4

excluding projecting parts and controls

• Mass

Approx. 282 g (10.0 oz) (main unit only)

• Supplied accessories

Stereo headphones or earphones (1) Belt clip (1)

Design and specifications are subject to change without notice.

Battery life (approximate hours) (JEITA*)

Sony alkaline LR6 (SG)** 32 40 Sony R6P (SR) 9 14

Tape Radio playback reception

E Model

Model Name Using Similar Mechanism NEW T ape Transport Mechanism T ype MF-WMFS421-114

⁄4 × 4 7⁄8 × 2 1⁄8 inches),

9-873-121-11

* Measured value by the standard of JEITA (Japan Electronics

and Information Technology Industries Association). (Using a Sony HF series cassette tape)

**When using Sony LR6 (SG) “STAMINA” alkaline dry

batteries (produced in Japan).

Note

•The battery life may be shorter depending on the operating condition, the surrounding temperature and battery type.

Sony Corporation

Personal Audio Company Shinagawa Tec Service Manual Production Group

RADIO CASSETTE PLAYER

WM-FS421

TABLE OF CONTENTS

1. GENERAL ·········································································· 2

2. SERVICE NOTE ······························································· 3

3. DISASSEMBLY

3-1. Main Assy······································································4 3-2. Chassis Sub Assy··························································· 5 3-3. MAIN Board and Mechanism Deck······························ 5 3-4. Belt ················································································ 6 3-5. Head, Magnetic (HP701)··············································· 6

4. MECHANICAL ADJUSTMENT ·································· 7

5. ELECTRICAL ADJUSTMENT ···································· 7

6. DIAGRAMS

6-1. IC Block Diagrams ······················································ 10 6-2. Block Diagram ···························································· 11 6-3. Printed Wiring Board··················································· 12 6-4. Schematic Diagram ····················································· 13 6-5. IC Pin Function Description········································ 14

7. MEXPLODED VIEWS

7-1. Cabinet Assy Section ··················································· 15 7-2. MAIN Board Section ·················································· 16 7-3. Mechanism Deck Section-1

(MF-WMFS421-114) ·················································· 17

7-4. Mechanism Deck Section-2

(MF-WMFS421-114) ·················································· 18

8. ELECTRICAL PPARTS LIST ···································· 19

SET

ENTER

PRESET +/–

Y (FS422ST/FS421 only)

Y (FS422ST/FS421 uniquement)

OFF

HOLD

SECTION 1

GENERAL

VOLUME

Display Afficheur

TUNING +, – FM, AM

Air outlet Evacuation d’air

This section is extracted from instruction manual.

Rubber cap Capuchon en caoutchouc

Notes on chip component replacement

• Never reuse a disconnected chip component.

• Notice that the minus side of a tantalum capacitor may be damaged by heat.

Flexible Circuit Board Repairing

• Keep the temperature of soldering iron around 270˚C during repairing.

• Do not touch the soldering iron on the same conductor of the circuit board (within 3 times).

• Be careful not to apply force on the conductor when soldering or unsoldering.

WATER PROOF SECTION

)

WM-FS421

SECTION 2

SERVICE NOTE

Note : In case the parts in the figure are removed for repair, treat them to protect from water drop following the instructions in the figure

• Sony grease SGL-601 : 7-651-000-10

(spread grease, bond etc.)

O Ring (Dia. 2.5 × Dia. 4.5) (Apply sony grease: SGL-601)

Tapping screw (B)(1.4 × 4)

Knob (Hold)

Joint (AVLS)

Tapping screw (B)(1.4

Joint (VOL)

O Ring (Apply sony grease: SGL-601

Knob (Vol)

WM-FS421

)

DISASSEMBLY

Note : Disassemble the unit in the order as shown below.

SECTION 3

Set

Main Assy

Chassis Sub Assy

MAIN Board and Mechanism Deck

Note : Follow the disassembly procedure in the numerical order given.

3-1. MAIN ASSY

Two screws (+B1.7 × 7)

(Be careful not to focibly pull the wire that connects the main board and the headphone board.)

Cassette sub assy, holder

Screw, tapping

Belt Head, Magnetic (HP701

Remve the main assy in the direction of arrow.

Remove the HEADPHONE

borad in the direction of arrow.

Stop ring (E 1.2)

CAUTION WHEN ASSEMBLING THE MAIN Assy

• Assemble the main Assy in a way that each switch mates with the corresponding knob each other.

HOLD •

(S701)

VOLUME

(RV301)

3-2. CHASSIS SUB ASSY

)

MAIN board

T wo claw

WM-FS421

3-3. MAIN BOARD AND MECHANISM DECK

MAIN board

Remove the solder

Chassis sub assy

Screw (M1.4 ) Toothed Lock

Remove the solder (four points

Stopper (L2)

Mechanism deck

WM-FS421

3-4. BELT

Belt

Belt threading

3-5. HEAD, MAGNETIC (HP701)

Capstan wheel assy(SP)

Two screws (M1.4)

Belt

Reel/Capstan motor

Capstan wheel assy(SP)

Head, magnetic (HP701)

SECTION 4

Test tape

WS-48A

(3 kHz, 0 dB)

Set

J301 (

)

Ω

digital frequency counter

+ –

MECHANICAL ADJUSTMENT

WM-FS421

SECTION 5

ELECTRICAL ADJUSTMENT

PRECAUTION

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

playback head pinch roller rubber belts capstan

2. Do not use a magnetized screwdriver for the adjustments.

Torque Measurement

Mode

FWD

Back T ension

FF, REW

Torque Meter

CQ-102C

CQ-201B

Meter Reading

2.0 to 4.1 N•m

(20 to 42 g•cm)

(0.27 to 0.58 oz•inch)

More tham 0.20 N•m

(More than 2.0 g•cm)

(More than 0.027 oz•inch)

More tham 4.9 N•m

(More than 50 g•cm)

(More than 0.69 oz•inch)

TAPE SECTION

Test T ape

Tape

WS-48A

Tape Speed Adjustment

Procedure:

Mode: Playback

Adjustment V alue: normal tape speed Adjust the tape speed adjustment R V601, so that the freqency counter reading becomes 3,000Hz.

Signal

3 kHz, 0 dB

0 dB = 0.775 V

Used for

Tape speed adjustment

Specification V alue:

Digital frequency counter

2,970 to 3,030 Hz

Frequency difference between the beginning and the end of the tape should be within 1.5 % (45 Hz).

Adjustment Location:

RV601

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