WM-FS420/FS420RS
US Model
Canadian Model
WM-FS420/FS420RS
AEP Model
E Model
WM-FS420
SERVICE MANUAL
RADIO CASSETTE PLAYER
SPECIFICATIONS
Model Name Using Similar Mechanism
NEW
Tape Transport Mechanism Type
MF-WMFS420-114
Radio Frequency
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 (AA)
× 2
Dimensions (w/h/d)
Approx. 108.4
× 125.7 × 47.2 mm
(4 3/8
× 5 × 1 7/
8
inches) incl.
projecting parts and controls
Mass
Approx. 280 g (9.9 oz)/Approx. 355 g (12.6 oz)
(incl. batteries and a cassette)
Supplied Accessories
· Stereo headphones or earphones (1)
· Belt clip (1)
· Battery charger (1) (FS420RS only)
· Rechargeable battery
NC-WMAA, 1.2 V, 700 mAh, Ni-Cd (2) (FS420RS only)
· Rechargeable battery carrying case (1) (FS420RS only)
Design and specifications are subject to change without notice.
Ver 1.2 2001. 03
Sony Corporation
Audio Entertainment Group
General Engineering Dept.
9-927-679-12
2001C1600-1
© 2001.3
-- 2 --
TABLE OF CONTENTS
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.
SECTION 1
GENERAL
This section is extracted
from instruction manual.
1. GENERAL ·········································································· 2
2. SERVICE NOTE ······························································· 3
3. DISASSEMBLY
3-1. Main Assembly ······························································ 4
3-2. Chassis Sub Assy ··························································· 5
3-3. Main Board and Mechanism Deck ································ 5
3-4. Belt ················································································ 6
3-5. Head, Magnetic (HP901) ··············································· 6
4. MECHANICAL ADJUSTMENT ·································· 7
5. ELECTRICAL ADJUSTMENT ···································· 7
6. DIAGRAMS
6-1. IC Block Diagrams ······················································ 10
6-2. Block Diagram ···························································· 11
6-3. Schematic Diagram ····················································· 13
6-4. Printed Wiring Board ··················································· 15
6-5. IC Pin Function Description ········································ 17
7. MEXPLODED VIEWS
7-1. Cabinet Assy Section ··················································· 18
7-2. Main Board Section ····················································· 19
7-3. Mechanism Deck Section-1
(MF-WMFS420-114) ·················································· 20
7-4. Mechanism Deck Section-2
(MF-WMFS420-114) ·················································· 21
8. ELECTRICAL PPARTS LIST ···································· 22
-- 3 --
SECTION 2
SERVICE NOTE
WATER PROOF SECTION
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
(spread grease, bond etc.)
· Sony grease SGL-601 : 7-651-000-10
Tapping screw (B)(1.4
× 4)
Tapping screw (B)(1.4
× 4)
Joint (AVLS)
Joint (VOL)
Knob (Hold)
Knob (Vol)
Ring. O
(Apply sony grease: SGL-601)
Ring (Dia. 2.5
× Dia. 4.5). O
(Apply sony grease: SGL-601)
-- 4 --
SECTION 3
DISASSEMBLY
Note :
Follow the disassembly procedure in the numerical order given.
Set
Main Assembly
Chassis Sub Assy
Main Board and Mechanism Deck
Belt
Head, Magnetic (HP901)
Note :
Disassemble the unit in the order as shown below.
3-1. MAIN ASSEMBLY
6
Remve the main assembly in the direction
of arrow.
(Be careful not to focibly pull the wire that connects
the main board and the headphone board.)
7
Remove the headphone
borad in the direction of arrow.
1
Stop ring (E 1.2)
5
Two screws (+B1.7
× 7)
3
Screw, tapping
2
Screw, tapping
4
Cassette sub assembly, holder
CAUTION WHEN ASSEMBLING THE MAIN ASSEMBLY
· Assemble the main assembly in a way that each switch mates with the corresponding knob each other.
DIR switch (S301)
POWER switch (S303)
DX/LOCAL switch
(S304)
Volume (RV301)
-- 5 --
3-2. CHASSIS SUB ASSY
Main board
2
Knob (DX-Local)
1
Two claws
3
Chassis sub assy
3-3. MAIN BOARD AND MECHANISM DECK
3
Screw (M1.4 ) Toothed Lock
1
Remove the solder (fouf points)
5
Stopper (MD)
4
Main board
2
Remove the solder
6
Mechanism deck