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WM-GX221
US Model
Canadian Model
E Model
Chinese Model
SERVICE MANUAL
RADIO CASSETTE-CORDER
Sony Corporation
Personal Audio Company
Published by Sony Engineering Corporation
9-873-412-03
2004D16-1
© 2004.04
SPECIFICATIONS
Ver 1.2 2004.04
Model Name Using Similar Mechanism
New
Tape Transport Mechanism Type
MT-WMGX221-175
Frequency range
FM:
87.5-108 MHz (Italy and Saudi Arabia)
87.6-108 MHz (North, Central and South America)
87.6-107.9 MHz (Other countries)
AM:
526.5-1 606.5 kHz (Italy and Saudi Arabia)
530-1 710 kHz (North, Central and South America)
531-1 602 kHz (Other countries)
Frequency response
Playback: 40 - 15 000 Hz
Recording: 100 - 8 000 Hz (when
setting 2x REC TIME to NORM)
Input
Microphone (MIC) jack
Output
Headphones (i) jack
Load impedance 8 - 300
Power requirements
3 V DC batteries R6 (size AA)
× 2
External DC 3V power sources
Dimensions (w/h/d)
Approx. 112.0
× 82.5 × 38.0 mm
(4 1/
2 × 3
1/
4 × 1
1/
2 inches), excl.
projecting parts and controls
Mass
Approx. 190 g (6.8oz) (main unit
only)
Supplied accessories
Stereo headphones or earphones (1)
Stereo microphone (1)
Carrying case (1)
Design and specifications are subject to change without notice.
Battery life (Approx. hours)
(JEITA*)
Sony alkaline LR6(SG) ** Sony R6P(SR)
(using headphones/earphones)
playback
24
7
radio
48
15
mic recording
20
4.5
radio recording
12
3
(using the speakers)
playback
15
4.5
radio
26
6
radio recording
11.5
3
*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.


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2
TABLE OF CONTENTS
WM-GX221
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.
1. SERVICE NOTE ··············································································· 3
2. GENERAL ·························································································· 4
3. DISASSEMBLY ················································································ 5
3-1. Panel (Cabinet Front), Cabinet (Front) Assy ·································· 5
3-2. MAIN Board, Mechanism Deck (MT-WMGX221-175) ················ 6
3-3. HE901, HRP901, M601, Belts ························································ 7
3-4. SUB Board ······················································································ 7
4. MECHANICAL ADJUSTMENT ·················································· 8
5. ELECTRICAL ADJUSTMENT ······················································ 8
6. DIAGRAMS ······················································································ 10
6-1. Block Diagram ­ Tuner Section ­ ················································· 11
6-2. Block Diagram ­ Main Section ­ ················································· 12
6-3. Printed Wiring Boards ·································································· 13
6-4. Schematic Diagram ­ MAIN Board (1/2) ­ ·································· 14
6-5. Schematic Diagram ­ MAIN Board (2/2) ­ ·································· 15
6-6. IC Block Diagrams ······································································· 16
7. EXPLODED VIEWS ······································································ 17
7-1. Overall Section ············································································· 17
7-2. Cabinet (Front) Section ································································· 18
7-3. Mechanism Deck Block-1 (MT-WMGX221-175) ······················· 19
7-4. Mechanism Deck Block-2 (MT-WMGX221-175) ······················· 20
8. ELECTRICAL PARTS LIST ······················································· 21


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3
WM-GX221
SECTION 1
SERVICE NOTE
In this set, record/play mode is detected using the switch S704 (TAPE POWER).
S704 is mounted on the MAIN board. If MAIN board is removed, it becomes impossible to detect
record/play mode.
Where MAIN board is removed, when you measure operation and voltage of each part of the mechanism
deck, please turn on S704.
­ MAIN BOARD (SIDE A) --
S704


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4
WM-GX221
SECTION 2
GENERAL
This section is extracted
from instruction manual.
* There is a tactile dot beside VOL on the main unit to show the direction to turn up the
volume.
** The button/jack has a tactile dot.
PAUSE
z REC
FLUNCTION (TAPE/RADIO)
NORM/CrO 2/METAL·
FM ST/MONO
DX/LOCAL
ISS
Built-in microphone
DC IN 3V
SPEAKER/ i
i
x STO P
N PLAY**
VOL *
BAND (FM/AM)
SOUND BOOST
(OFF/ON)
TUNING
REC/BATT indicator
Tuning indicator
MIC (PLUG IN POWER)**
2x REC TIME
(NORM/DOUBLE)
AVLS (NORM/LIMIT)
mREW/REVIEW
MFF/CUE
· LOCATION OF CONTROLS


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5
WM-GX221
SECTION 3
DISASSEMBLY
Note : Disassemble the unit in the order as shown below.
Note :
Follow the disassembly procedure in the numerical order given.
3-1.
PANEL (CABINET FRONT), CABINET (FRONT) ASSY
two screws (B1.7
× 1.4)
1
2
screw (B1.7
× 1.4)
1
two screws (B1.7
× 1.4)
3
two screws
3
screw
3
screw (B1.7
× 1.4)
1
two screws (B1.7
× 9)
3
Remove solder.
(two places)
6
Remove solder.
(two places)
6
cabinet (front) assy
panel (cabinet front)
four claws
4
claw
4
two claws
4
flexible board
5
cabinet center
Panel (cabinet front), Cabinet (front) assy
MAIN board, Mechanism deck (MT-WMGX221-175)
HE901, HRP901, M601, Belts
SUB board
Set