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WM-GX670/GX674
US Model
AEP Model
UK Model
Australian Model
WM-GX670
Chinese Model
E Model
WM-GX670/GX674
SERVICE MANUAL
RADIO CASSETTE CORDER
Sony Corporation
Personal Audio Company
Published by Sony Engineering Corporation
9-926-924-12
2002A1600-1
© 2002.1
Ver 1.2 2002. 01
Manufactured under license from Dolby Laboratories
Licensing Corporation.
"DOLBY" and the double-D symbol
aare trademarks
of Dolby Laboratories Licensing Corporation.
Model Name Using Similar Mechanism
WM-EX677
Tape Transport Mechanism Type
MT-WMGX670-162
SPECIFICATIONS
Radio section
Frequency range
FM: 65 ­ 74/87.5 ­ 108MHz (Eastern
Europe)
87.5 ­ 108MHz (other countries)
AM: 530 ­ 1,710kHz (North, Central,
and South America)
531 ­ 1,602kHz (other countries)
Tape section
Frequency response
(Dolby NR off)
Playback: 40 ­ 15,000Hz
Recording/playback: 100 ­ 8,000Hz
Output
Headphones (
2 REMOTE) jack
Load impedance 8 ­ 300
Input
Microphone (MIC) jack
General
Power requirements
1.5V
Rechargeable battery
One R6 (size AA) battery
Dimensions (w/h/d)
Approx. 108.4
× 77.7 × 23.8 mm
(43/8
× 31/8 × 15/16inches), incl.
projecting parts and controls
Mass
Approx. 250g (8.9oz)
Approx. 315g (11.2oz) incl.
rechargeable battery and a cassette
Supplied accessories
Battery case (1)
Stereo earphones with remote control (1)
Battery charge (1)
AC plug adaptor (1) (except for European,
Australian, Saudi Arabian, Chinese, Hong Kong,
U.S.A., Canadian, and Korean model)
Rechargeable battery (NC-6WM, 1.2V, 600mAh,
Ni-Cb) (1)
Rechargeable battery carring case (1)
Carrying pouch (1)
Stereo microphone (1)
Design and specifications are subject to change without notice
Photo: WM-GX670


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-- 2 --
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.
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK
! OR DOTTED LINE WITH
MARK
! ON THE SCHEMATIC DIAGRAMS AND IN THE PARTS
LIST ARE CRITICAL TO SAFE OPERATION. REPLACE THESE
COMPONENTS WITH SONY PARTS WHOSE PART NUMBERS
APPEAR AS SHOWN IN THIS MANUAL OR IN SUPPLEMENTS
PUBLISHED BY SONY.
TABLE OF CONTENTS
1. SERVICE NOTE ······························································· 3
2. GENERAL ·········································································· 5
3. DISASSEMBLY
3-1. Case Block Assembly ····················································· 6
3-2. Belt (F2) ·········································································· 7
3-3. Cassette Lid Assembly ···················································· 7
3-4. Reel Ornament Assembly ··············································· 8
3-5. Main Board ····································································· 8
3-6. Motor (F2) (M901) ························································· 9
3-7. Holder Assembly ····························································· 9
3-8. Pinch Lever (N)/(R) Assembly ····································· 10
3-9. Magnetic Head (HP901) ··············································· 10
4. MECHANICAL ADJUSTMENT ································ 11
5. ELECTRICAL ADJUSTMENT ·································· 11
6. DIAGRAMS
6-1. Block Diagram ······························································ 13
6-2. Printed Wiring Board ···················································· 16
6-3. Schematic Diagram (1/2) ·············································· 19
6-4. Schematic Diagra (2/2) ················································· 22
6-5. IC Block Diagrams ······················································· 25
6-6. IC Pin Function Discription ·········································· 27
7. EXPLODED VIEWS
7-1. Cabinet Block, Main Board ·········································· 29
7-2. Mechanism Deck Block ················································ 30
8. ELECTRICAL PARTS LIST ······································· 31


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-- 3 --
p
(S3)
ENTER
(S10)
REC
(S11)
BAND
(S8)
MENU
(S6)
R43
(SIDE A)
Q15
(SIDE A)
SET
(S7)
(S1)
FWD
STOPREV
Battery terminal
'
Battery terminal
`
Square-wave
(sine wave)
10 Hz, -3.5 dB
AF OSC
Plunger (PM901)
Short
Short
TAPE DETECT
SWITCH
(S901-2)
R TUME
SWITCH
(S901-1)
FF AMS
(S4)
REW AMS
(S5)
oeREPEAT
(S9)
F TUME
SWITCH
(S902-1)
ATS
SWITCH
(S902-2)
M601
M
SECTION 1
SERVISE NOTE
[Service Mode]
The service mode enables to operate the mechanism of WM-GX670/
GX674 while the MAIN board is opened.
Rotation of the idler gear (A) (S side) is detected using the photo-
reflector (PH1) in the WM-GX670/GX674. PH1 is located on the
MAIN board, therefore the rotation of the idler gear (A) (S side)
cannot be detected by PH1 when the MAIN board is removed. As
a result, the motor cannot be controlled and cannot run correctly.
To repair the machine after the MAIN board is removed while the
main power is turned on, follow the procedures as described below.
1. Setting
1)
Remove the cabinets referring to section "3. DISASSEMBLY".
Open the MAIN board.
2)
Connect the motor (M601) and the plunger solenoid (PM901)
to the MAIN board using the jumper wires. When the extension
jig (1-769-143-11) (10 wires as a set) is used, they can be
connected easily.
3)
Short the TAPE DETECT switch (S901-2), R TUME switch
(S901-1), F TUME switch (S902-1) and ATS switch (S902-2).
4)
Connect an AF oscillator to resistor (R43).
5)
Connect DC 1.3 V from external regulated power supply to
`
and
' terminals of the battery.
2. PRE-SET status
The PLAY, FF and REW modes can be entered only from the PRE-
SET status.
1)
Check that the slider (NR) is in the center position (S1), and
the FWD/REV switch is also in the center position. When
these switches are not in the center position, set them to the
PRE-SET status as follows.
2)
Move the FWD/REV switch (S1) to the same position as the
slider (NR) is set.
3)
The slider (NR) can be moved when the main power of the
regulated power supply is turned OFF once then back ON.
Move the FWD/REV switch (S1) to the center position in
synchronism with the timing when the slider (NR) is moved.
3. FF, REW modes
1)
Check that the PRE-SET status is set.
2)
Connect square wave or sine wave to resistor (R43). (See
illustration below.)
3)
Press the
p switch (S3) to enter the STOP mode.
4)
Press the FF AMS switch (S4) and the REW AMS switch
(S5).
4. PLAY mode
1)
Check that the PRE-SET status is set.
2)
Connect square wave or sine wave to resistor (R43). (See
illustration below.)
3)
Press the
p switch (S3) to enter the stop mode.
4)
When the
9(REPEAT switch (S9) of the MAIN board is
pressed, the slider (N/R) moves once to the F side then moves
to the R side. When the FWD/REV switch (S1) is pressed in
the synchronism with the above timing, the machine can enter
the PLAY (R side) mode. Press the
9(REPEAT switch
(S9) again, and move the FWD/REV switch (S1) in the
synchronism with the motion of slider (NR). It enables the
machine to enter into the PLAY (F side) mode.
Note 1: When you fail to enter the PLAY mode, re-start from step
1) PRE-SET status.
Note 2: Regarding the
9(REPEAT (S9), p (S3),
FF AMS (S4), and REW AMS (S5) switches, use these
switches of the remote control unit as much as possible.
Note 3: If a headphones are used, the beep sound shows the timing
of the FWD/REV switch (S1).
­ MAIN BOARD (SIDE B) --


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-- 4 --
[ Slider (NR) ]
[ Tape drive mechanism ]
Tape drive mechanism in PLAY mode
Tape drive mechanism in FF mode
Tape drive mechanism in REW mode
Slider (NR)
Center
F side R side
Insert Flywheel (N)
Pulley (Reverse)
Clutch Assy
Motor Pulley
Gear (REEL)(S side)
Gear
(REEL)(T side)
Gear (NR)
(FWD : Left side
REV : Right side)
Idler Gear
Idler Gear (A)(S side)
Idler Gear
(A)(T side)
Insert Flywheel (R)
Cam Gear
Gear (Y)
Insert Flywheel (N)
Pulley (Reverse)
Clutch Assy
Motor Pulley
Gear
(REEL)(T side)
Idler Gear
(A)(T side)
Insert Flywheel (R)
Cam Gear
Gear (Y)
Gear (FR)
(FF : Left side)
Insert Flywheel (N)
Pulley (Reverse)
Clutch Assy
Motor Pulley
Gear
(REEL)(S side)
Idler Gear
(A)(S side)
Insert Flywheel (R)
Cam Gear
Gear (Y)
Gear (FR)
(REW : Right side)


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-- 5 --
SECTION 2
GENERAL
12
3
4
5
6
7
8
9
!TM
!
1
5
3
4
2
2
1
3
4
6
5
· LOCATION OF CONTROLS
· LOCATION OF REMOTE CONTROL
(WM-GX670 model)
· LOCATION OF REMOTE CONTROL
(WM-GX674 model)
1 2 REMOTE jack
2 REW, AMS button
3 " ", REPEAT button
4 FF, AMS button
5 OPEN knob
6 Battery case
7 Display window
8 HOLD c knob
9 SET button
!º MENU button
!¡ BAND, PADIO ON button
!TM ENTER, COUNTER RESET button
!£ REC button
!¢ p, RADIO OFF button
! VOL knob
!§ ISS (1, 2, 3) knob
!¶ MIC (PLUG IN POWER) jack
1 FF, PRESET+ button
2 " " · p, RADIO ON/BAND OFF button
3 HOLD knob
4 REW, PRESET­ button
5 VOL knob
1 HOLD button
2 DISPLAY window
3 MENU button
4 JOG lever
5 REC button
6 VOL knob