Sony WMGX-780 Service manual
WM-GX780/GX788
SERVICE MANUAL
Ver 1.1 2003. 10
Photo: WM-GX788
US Model
AEP Model
WM-GX788
E Model
Chinese Model
WM-GX780/GX788
Tourist Model
WM-GX788
Model Name Using Similar Mechanism NEW
Tape Transport Mechanism T ype MF-WMGX788-162
SPECIFICATIONS
Radio section
Frequency range
FM:
87.5 - 108 MHz
530 - 1 710 kHz (North, Central,
AM:
and South America)
531 - 1 602 kHz (other
countries/regions)
Tape section
Frequency response
Playback: 40 - 15 000 Hz
Recording/playback: 100 - 8 000 Hz
Output
Headphones (i) jack
Load impedance 8 - 300 Ω
Input
Microphone (MIC) jack
General
Power requirements
1.5 V
Rechargeable battery
One R6 (size AA) battery
Dimensions (w/h/d)
Approx. 77.1 × 108.0 × 22.5 mm
1
(3
⁄8 × 43⁄8 × 29⁄32 inches) excl. projecting
parts and controls
Mass
Approx. 152 g (5.4 oz) (main unit only)
Supplied accessories
AC power adaptor (1)
Battery case (1)
Stereo headphones or earphones with
remote control (1)
Charging stand (1)
AC plug adaptor (1) (Saudi Arabian
model only)
Rechargeable battery (NH-14WM(A),
1.2 V, 1 350 mAh (min), Ni-MH) (1)
Rechargeable battery carrying case (1)
Carrying pouch (1)
Stereo microphone (1)
Design and specifications are subject to
change without notice.
9-877-201-02
2003J16-1
© 2003.10
RADIO CASSETTE-CORDER
Sony Corporation
Personal Audio Company
Published by Sony Engineering Corporation
WM-GX780/GX788
TABLE OF CONTENTS
1. SERVICE NOTE······························································· 3
2. GENERAL ··········································································5
3. DISASSEMBLY
3-1. Case Block Assy ····························································· 6
3-2. Button Rec, Button Assy················································· 7
3-3. Cassette Lid Assy···························································· 7
3-4. Ornament Block Assy Reel, Flexible Retainer ··············· 8
3-5. MAIN Board, Belt (F0) ·················································· 8
3-6. Motor (M901) ·································································9
3-7. Bracket (cassette) Assy, Holder (FA) Assy ····················· 9
3-8. Pinch Lever (RA) Assy, Pinch Lever (NA) Assy ·········· 10
3-9. Magnetic Head (HP901) ··············································· 10
4. MECHANICAL ADJUSTMENT ································ 11
5. ELECTRICAL ADJUSTMENT ··································11
6. DIAGRAMS······································································12
6-1. Block Diagram ······························································ 13
6-2. Printed Wiring Board (Side A) ······································ 14
6-3. Printed Wiring Board (Side B)······································ 15
6-4. Schematic Diagram (1/2) ·············································· 16
6-5. Schematic Diagram (2/2) ·············································· 17
6-6. IC Block Diagrams ······················································· 18
6-7. IC Pin Function Discription ·········································· 19
7. EXPLODED VIEWS
7-1. Case Section·································································· 21
7-2. Main Section ································································· 22
7-3. Mechanism Deck Section (MF-WMGX788-162) ········ 23
8. ELECTRICAL PARTS LIST ······································· 24
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE WITH
MARK 0 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 .
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.
UNLEADED SOLDER
Boards requiring use of unleaded solder are printed with the leadfree mark (LF) indicating the solder contains no lead.
(Caution: Some printed circuit boards may not come printed with
the lead free mark due to their particular size)
: LEAD FREE MARK
Unleaded solder has the following characteristics.
• Unleaded solder melts at a temperature about 40 ˚C higher than
ordinary solder.
Ordinary soldering irons can be used but the iron tip has to be
applied to the solder joint for a slightly longer time.
Soldering irons using a temperature regulator should be set to
about 350 ˚C .
Caution: The printed pattern (copper foil) may peel away if the
heated tip is applied for too long, so be careful!
• Strong viscosity
Unleaded solder is more viscous (sticky , less prone to flow) than
ordinary solder so use caution not to let solder bridges occur
such as on IC pins, etc.
• Usable with ordinary solder
It is best to use only unleaded solder but unleaded solder may
also be added to ordinary solder.
2
SECTION 1
SERVICE NOTE
[Service Mode]
The service mode enables to operate the mechanism of WM-GX780/
GX788 while the MAIN board is opened.
Rotation of the idler gear (A) (S side) is detected using the photoreflector (PH701) in the WM-GX780/GX788. PH701 is located on
the MAIN board, therefore the rotation of the idler gear (A) (S side)
cannot be detected by PH701 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. DISASSEMBL Y”.
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 (S303), REV TUME switch
(S503), FWD TUME switch (S502) and ATS switch (S302).
4) Connect an AF oscillator to resistor (R712).
5) Connect DC 1.3 V from external re gulated power supply to ‘
and ’ terminals of the battery.
2. PRE-SET status
The PLA Y, FF and REW modes can be entered only from the PRESET status.
1) Check that the slider (NR) is in the center position (S801), 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 (S801) 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 (S801) to the center position in
synchronism with the timing when the slider (NR) is moved.
WM-GX780/GX788
3. FF, REW modes
1) Check that the PRE-SET status is set.
2) Connect square wave or sine wave to resistor (R712). (See
illustration below.)
3) Press the x switch (S703) to enter the STOP mode.
4) Press the FF PRESET+ switch (S708) and the REW PRESET–
switch (S707).
4. PLAY mode
1) Check that the PRE-SET status is set.
2) Connect square wave or sine wave to resistor (R712). (See
illustration below.)
3) Press the x switch (S703) to enter the STOP mode.
4) When the nNREPEAT switch (S709) of the MAIN board
is pressed, the slider (NR) moves once to the F side then moves
to the R side. When the FWD/REV switch (S801) is pressed
in the synchronism with the above timing, the machine can
enter the PLAY (R side) mode. Press the nNREPEAT
switch (S709) again, and move the FWD/REV switch (S801)
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 nNREPEAT (S709), x (S703),
FF PRESET+ (S708), and REW PRESET– (S707)
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 (S801).
REV TUME
SWITCH
(S503)
Short
TAPE DETECT
SWITCH
(S303)
Battery terminal
ENTER
(S702)
SET
(S705)
MENU
(S706)
– MAIN BOARD (SIDE B) —
Plunger (PM901)
#
REC
(S710)
RADIO ON/
BAND
(S704)
R710
(Side A)
Y
REPEAT
(S709)
REW/PRESET–
(S801)
FWD
←
STOP→REV
(S707)
OSC
Sine wave
10 Hz, -3.5 dB
FF/PRESET+
(S708)
ATS
SWITCH
(S302)
FWD TUME
SWITCH
(S502)
Battery terminal
x
RADIO OFF
(S703)
Short
M
3
M601
3
WM-GX780/GX788
y
[ Slider (NR) ] [ Tape drive mechanism ]
Tape drive mechanism in PLAY mode
Gear (NR)
(FWD : Left side
REV : Right side)
Idler Gear
(A)(T side)
Gear
Idler Gear(B)
F side
Center
Slider (NR)
(REEL)(T side)
Cam Gear
R side
Gear (Y)
Idler Gear (A)(S side)
Gear (REEL)(S side)
Motor Pulley
Clutch Assy(F)
Tape drive mechanism in FF mode
Idler Gear
(A)(T side)
Gear
(REEL)(T side)
Cam Gear
Gear (Y)
Gear (FR)
(FF : Left side)
Clutch Assy(F)
Motor Pulle
Insert Flywheel (N)
Insert Flywheel (R)
Tape drive mechanism in REW mode
Gear (FR)
(REW : Right side)
Cam Gear
Gear (Y)
Idler Gear
(A)(S side)
Clutch Assy(F)
Pulley (Reverse)
Gear
(REEL)(S side)
Motor Pulley
Insert Flywheel (N)
4
Pulley (Reverse)
Insert Flywheel (R)
Pulley (Reverse)
Insert Flywheel (N)
Insert Flywheel (R)
• LOCATION OF CONTROLS
FF/CUE
REW/REVIEW
Y•REPEAT**
VOL*
SET
MENU
HOLD
WM-GX780/GX788
SECTION 2
GENERAL
Plug in firmly.
i
x
ISS
MIC**
HOLD
VOL
REW –
FF +
Y•x
This section is extracted
from instruction manual.
ENTER
SET
MENU
RADIO ON/BAND
TUNE/PRESET –/+
RADIO OFF
MENU
SET
REC
x
FF +
REW –
RADIO ON/BAND
OFF
SPEED
CONTROL
MENU
SET
COUNTER RESET
ENTER/
HOLD
Tape counter
HOLD SOUND
MODE
5
WM-GX780/GX788
DISASSEMBLY
Note : Disassemble the unit in the order as shown below.
SET
CASE BLOCK ASSY
SECTION 3
CASSETTE LID ASSY
ORNAMENT BLOCK ASSY REEL,
FLEXIBLE RETAINER
MAIN BOARD, BELT (F0)
MOTOR (M901)
BRACKET (CASSETTE) ASSY,
HOLDER (FA) ASSY
PINCH LEVER (RA) ASSY,
PINCH LEVER (NA) ASSY
MAGNETIC HEAD (HP901)
Note : Follow the disassembly procedure in the numerical order given.
3-1. Case Block Assy
7
Remove the case block assy
in the direction of the arrow.
BUTTON REC,
BUTTON ASSY
knob (iss)
4
two screws
(M1.4)(EG)
S501
Note: On installation case block assy
adjust the S501 and knob (iss).
2
claw
5
3
battery lid
6
two screws
(M1.4)(EG)
screw
(M1.4)(EG)
1
Open the battery lid.
6
3-2. Button Rec, Button Assy
)
)
2
5
knob (hold)
button rec
1
rec spring
3
torion spring (hold
4
button assy
WM-GX780/GX788
3-3. Cassette Lid Assy
5
cassette lid assy
3
Slide the knob (open)
in the direction of the arrow.
4
shaft
2
two screws
(M1.4)(EG)
1
screw (M1.4)(EG
7
WM-GX780/GX788
f
3-4. Ornament Block Assy Reel, Flexible Retainer
2
claw
3
claw
5
ornament block assy reel
4
boss
1
claw
3
claw
1
claw
3-5. MAIN Board, Belt (F0)
8
6
screw (M1.4)
9
belt (F0)
7
flexible retainer
6
screw (M1.4)
3
Remove two solders
of plunger solenoid.
MAIN board
4
Remove four solders
of leaf switch.
5
two screws
2
Remove three solders o
ATS flexible board.
1
Remove four solders of motor.
7
flexible board (head)
8
3-6. Motor (M901)
)
1
two screws (M1.4)
2
motor (M901)
3
motor retainer (F1
WM-GX780/GX788
3-7. Bracket (cassette) Assy, Holder (FA) Assy
3
screw (M1.4)
8
holder (FA) assy
6
flexible board (head)
7
shaft
5
bracket (cassette) assy
4
shaft
2
lock lever (B)
1
two screws
(M1.4
×
1.6)
9
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