Sony WALKMAN WM-GX680 User manual

WM-GX680/GX688
US Model
AEP Model
WM-GX680
E Model
Tourist Model
WM-GX688
Chinese Model
WM-GX680/GX688
SERVICE MANUAL
Sony Corporation
Personal Audio Company
Published by Sony Engineering Corporation
9-873-034-12
2002A1600-1
© 2002.1
Ver 1.2 2002. 01
RADIO CASSETTE-CORDER
Model Name Using Similar Mechanism WM-GX677
Tape Transport Mechanism Type MF-WMGX670-162
SPECIFICATIONS
Manufactured under license from Dolby Laboratories
Licensing Corporation.
“DOLBY” and the double-D symbol aare trademarks
of Dolby Laboratories Licensing Corporation.
Radio section
Frequency range
FM : 76.0 ~ 90.0 MHz (Tourist Model)
: 87.5 ~ 108 MHz (Other Models)
AM : 531 ~ 1710 kHz (Tourist, US Models)
: 531 ~ 1 602 kHz (Other Models)
Tape section
Frequency response
(Dolby NR off)
Playback: 40 - 15 000 Hz
Recording/playback: 100 - 8 000 Hz
Output
Headphones (iREMOTE) 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. 108.4 ×77.7 ×23.0 mm
(43⁄8×31⁄8×29⁄32 inches)
Mass
Approx. 148 g (5.3 oz)
Supplied accessories
Battery case (1)
Stereo headphones or earphones with
remote control (1)
Battery charger (1)
AC plug adaptor (1) (Saudi Arabian,
Tourist model)
Rechargeable battery (NC-6WM, 1.2 V,
600 mAh, Ni-Cd) (1)
Rechargeable battery carrying case (1)
Carrying pouch (1)
Stereo microphone (1)
Design and specifications are subject to
change without notice.
Photo: WM-GX688

—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 LINEWITH
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 assy········································································· 6
3-2. Belt ·················································································· 7
3-3. Lid block assy, cassette ··················································· 7
3-4. Ornament, reel ································································ 8
3-5. Main Board ····································································· 8
3-6. Motor (M601) ································································· 9
3-7. Holder (F) Assy······························································· 9
3-8. Lever (N)/(R)Assy, pinch ············································· 10
3-9. Head, magnetic (HP901)··············································· 10
4. MECHANICAL ADJUSTMENT ································ 11
5. ELECTRICAL ADJUSTMENT ·································· 11
6. DIAGRAMS
6-1. Block Diagram ······························································ 13
6-2. Schematic Diagram (1/3) ·············································· 16
6-3. Schematic Diagram (2/3) ·············································· 19
6-4. Schematic Diagram (3/3) ·············································· 21
6-5. IC Block Diagrams ······················································· 23
6-6. Printed Wiring Board (SIDE A)···································· 25
6-7. Printed Wiring Board (SIDE B) ···································· 27
6-8. IC Pin Function Discription ·········································· 29
7. EXPLODED VIEWS
7-1. Cabinet Block, Main Board ·········································· 31
7-2. Mechanism Deck Block················································ 32
8. ELECTRICAL PARTS LIST ······································· 33

—3 —
SECTION 1
SERVICE NOTE
[Service Mode]
Theservice mode enablestooperatethemechanismofWM-GX680/
688 while the MAIN board is opened.
Rotation of the idler gear (A) (S side) is detected using the photo-
reflector(PH1)intheWM-GX680/688. PH1islocatedontheMAIN
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) Removethe cabinets referringtosection“3.DISASSEMBLY”.
Open the MAIN board.
2) Connect the motor (M601) and the plunger solenoid (PM901)
totheMAINboardusingthe jumper wires. Whentheextension
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) andATS switch (S902-2).
4) Connect an AF oscillator to resistor (R43).
5) Connect DC 1.3V 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 pswitch (S3) to enter the STOP mode.
4) Press the FF PRESET+ switch (S4) and the REW PRESET–
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 pswitch (S3) to enter the STOP mode.
4) When the 9(REPEAT switch (S9) 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 (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 PRESET+ (S4), and REW PRESET–(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) —
p
(S3)
ENTER
(S10)
REC
(S11)
BAND
(S8)
MENU
(S6)
R43
(SIDE A)
Q15
(SIDE A)
SET
(S7)
(S1)
FWD
← STOP → REV
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 PRESET +
(S4)
REW PRESET –
(S5)
œ REPEAT
(S9)
F TUME
SWITCH
(S902-1)
ATS
SWITCH
(S902-2)
M601
M

—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(F)
Motor Pulley
Gear (REEL)(S side)
Gear
(REEL)(T side)
Gear (NR)
(FWD : Left side
REV : Right side)
Idler Gear(B)
Idler Gear (A)(S side)
Idler Gear
(A)(T side)
Insert Flywheel (R)
Cam Gear
Gear (Y)
Insert Flywheel (N)
Pulley (Reverse)
Clutch Assy(F)
Motor Pulle
y
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(F)
Motor Pulley
Gear
(REEL)(S side)
Idler Gear
(A)(S side)
Insert Flywheel (R)
Cam Gear
Gear (Y)
Gear (FR)
(REW : Right side)

—5 —
SECTION 2
GENERAL
•LOCATION OF CONTROLS
This section is extracted
from instruction manual.
x
VOL
VOL
HOLD
HOLD
Y•REPEAT
FF (AMS)
REW (AMS)
Y•x
REW
Plug in firmly.
iREMOTE
FF
PRESET –
RADIO OFF
SETMENU
TUNE/PRESET +
RADIO ON/
BAND•OFF
PRESET +
TUNE/PRESET – RADIO ON/BAND
ENTER
SOUND MODE MODE AVLS MODE a NR
PB TUNE FM PB
ENTER/COUNTER RESET
SET
MENU
Tape counter
HOLD HOLD

—6 —
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. CASE ASSY
3Screw (M1.4 ×2.0)
2Two screws
(M1.4 ×2.0)
1Lid, Battery
5Remove the case assy
in the direction of the arrow.
4Two screws
(M1.4 ×2.5)
knob (HOLD-B)
Claw
S11
S501
S2
Note: When assembling the
case assy, align the
knob (HOLD-B) with the
position of S2.
knob (ISS)
Note: When assembling the
case assy, align the
knob (ISS) with the
position of S501.
knob (REC)
Note: When assembling the
case assy, align the
knob (REC) with the
position of S11.
Set Case assy
Belt
Lid block assy, cassette Main board
Ornament, reel
Motor
(M601)
Holder (F)
assy
Lever (N)/(R) assy,
pinch
Head, magnetic
(HP901)

—7 —
3-2. BELT
3-3. LID BLOCK ASSY, CASSETTE
3Belt
Belt
2Terminal boar
d
(Battery ’)
1Remove solder from
the battery terminal board.
Belt threading
5Lid block assy, cassette
4Shaft
3Open the cassette lid
1Screw (M1.4 ×2.0)
2Two screws (M1.4 ×2.0)

—8 —
3-4. ORNAMENT, REEL
3-5. MAIN BOARD
1Ornament, reel
Remove the assembly while removin
g
the three claws and boss carefully.
Note:
Claw
Claw
SLIDER
8 Remove soldering
(two points)
from plunger solenoid.
6 Screw (B1.7 × 3)
tapping
5 Screw (B1.7 × 3)
tapping
3 Screw (1.4 × 1.6)
2 Screw (M1.4)
7 Screw (M1.4)
Toothed lock
1 Ats flexible board
4 Screw (M1.4)
9 Remove soldering
(four points) from
motor.
When assembling the MAIN board,
align the slider with the position of S1.
Note:
S1

—9 —
3-6. MOTOR (M601)
1Two screws (M1.4)
Toothed lock
2Motor (M601)
3-7. HOLDER (F) ASSY
4Screw (M1.4)
2Shaft
6Shaft
1Two screws (M1.4 ×1.6)
3Lever (B), lock
9Remove the holder (F)
assy in the direction
of the arrow.
5Lever (S), lock
8Flexible board
7Bracket (cassette) assy

—10 —
3-8. LEVER (N) / (R) ASSY, PINCH
3-9. HEAD, MAGNETIC (HP901)
Claw
Claw
Note: Be careful of the claw
1Remove the lever (R) assy, pinch
in the direction of the arrow.
2Remove the lever (N) assy, pinch
in the direction of the arrow.
Note: Be careful of the claw
1Two screws
(M1.4 ×7.2)
2Remove the head, magnetic (HP901)
in the direction of the arrow.

—11 —
SECTION 4
MECHANICAL ADJUSTMENT
SECTION 5
ELECTRICAL ADJUSTMENT
PRECAUTION
1. Specified voltage : 1.3 V (DC)
2. Switch and control position
MENU switch
HOLD : OFF
VOL : MAX
ISS : 1
TAPE SECTION
Tape Speed Adjustment
Procedure:
1. Enter the FWD playback mode.
2. Adjust RV601 so that the valueofthefrequencycounter reading
becomes 3,000 Hz.
Specification value:
Frequency counter
2,940 Hz –3,060 Hz
3. Check that the frequency deviation at the beginning and ending
of a tape is within 1.5 % (45 Hz).
PRECAUTION
1. Clean the following parts with a denatured-alcohol-moistened
swab:record/playback/erase head pinch roller
rubber belts capstan
2. Demagnetize the record/playback/erase head with a head
demagnetizer. (Do not bring a head demagnetizer close to the
erase head.)
3. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
•Torque Measurement
Signal
3 kHz, 0 dB
Used for
Tape Speed Adjustment
Tape
WS-48A
Test tape
WS-48A
(3kHz, 0dB)
Set
2REMOTE jack (J701)
16 ΩFrequency counter
+
–
[MAIN BOARD] —SIDE B —
‘
‘
’
RV601
L2
T2
TP6
TP5
IC2
13
241
12
T1
RV1
RV601 : Tape speed
adjustment
RV1 : FM VCO adjustment
T2 : AM IF adjustment
L2 : FM frequency coverage
adjustment
T1 : AM frequency coverage
adjustment
TP1
Adjustment Parts Location :
[MAIN BOARD] —SIDE A —
Mode
FWD
FWD
Back Tension
REV
REV
Back Tension
FF, REW
Torque Meter
CQ-102C
CQ-102C
CQ-102RC
CQ-102RC
CQ-201B
Meter Reading
1.47 to 2.45 mN•m
(15 to 25 g•cm)
(0.21 to 0.34 oz•inch)
Less than 0.20 mN•m
(Less than 2.0g•cm)
(Less than 0.028 oz•inch)
1.47 to 2.45 mN•m
(15 to 25 g•cm)
(0.21 to 0.34 oz•inch)
Less than 0.20 mN•m
(Less than 2.0g•cm)
(Less than 0.028 oz•inch)
More than 4.90 mN•m
(More than 50 g•cm)
(More than 0.69 oz•inch)

—12 —
[AM]
BAND switch : AM
[FM]
BAND : FM
•Repeat the procedures in each adjustment several times.
AM FREQUENCY COVERAGE ADJUSTMENT
Adjust for a maximum reading on level meter.
T1 531 kHz
Confirmation 1,710 kHz
FM VCO Adjustment
Procedure :
1. Connect frequency counter to the positions shown below.
2. Tune the set to 98 MHz.
3. Adjust RV1 so that the value of the frequency counter reading
becomes 19 kHz.
Specification Value :
Frequency counter
18,900 –19,100 Hz
TUNER SECTION
0.01µF
FM RF signal
generator
to ANT (TP1)
22.5kHz frequency deviation by 400Hz signal.
Output level : as low as possible
Put the lead-wire
antenna close to
the set.
30% amplitude modulation by 400Hz
signal.
Output level : as low as possible
AM RF signal
generator
16Ω
set +
–
level mete
r
2REMOTE jack (J701)
0.01µF
FM RF signal
generator
to ANT (TP1
)
Carrier frequency : 98MHz
Modulation : no modulation
Output level : 0.1V (100dB)
Frequency counte
r
1µF
+
–
100kΩ
TP5
(IC2 Pin !™)
TP6
(IC2 Pin 9)
0dB=1µV
Adjustment Location: MAIN board (See page 11)
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter.
T2 450 kHz
FM FREQUENCY COVERAGE ADJUSTMENT
Adjust for a maximum reading on level meter.
L2 76 MHz
Confirmation 108 MHz

WM-GX680/GX688
SECTION 6
DIAGRAMS
— 13 — — 14 — — 15 —
6-1. BLOCK DIAGRAM
• Waveform
Note on Printed Wiring Board:
•Y: parts extracted from the conductor side.
•b: Pattern from the side which enables seeing.
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ωand 1/4W or less unless otherwise
specified.
•f: internal component.
•C: panel designation.
•A: B+ Line.
•H: adjustment for repair.
• Power voltage is dc 1.5 V and fed with regulated dc power
supply from battery terminal.
• Voltages and waveforms are dc with respect to ground
under no-signal (detuned) conditions.
Main board (1/3)
no mark : FM/AM, TAPE STOP
( ) : FM
[ ] : AM
< > : TAPE PB
Main board (2/3), (3/3)
no mark : REC / PB
( ) : REC
[ ] : PB
• Voltages are taken with a VOM (Input impedance 10 MΩ).
Voltage variations may be noted due to normal produc-
tion tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
• Circled numbers refer to waveforms.
• Signal path.
E: PB
a: REC
F: FM
51.7kHz
1
TP32 20µsec/div
5V/div
2
IC2 !¶ VCO 5µsec/div
50mV/div
3
IC801 5PLAY BACK mode
75kHz
4
IC3 &¢ XOUT 5µsec/div
0.5V/div
5µsec/div
1V/div
14
B+1.5V
16
: FM
: PB (TAPE)
: REC (TAPE)
L-CH
1RF
AMP MIX
7
VCC
OSC
6
5
8
MIX OUT
IC1
FM RF/MIX
Q1,4
BUFFER
IF
AMP
Q7,14
L1
FM RF
D3
D2D1 L2
FM OSC
FM
FREQUENCY
COVERAGE
Q3
LOCAL/DX
CF1
10.7MHz 3IF AMP/
FM DET
X1
10.7MHz
7
IC2
IF AMP/MPX
22
AF
CF2
450KHz 6IF AMP/
AM DET
T2
AM IF
5
4
VCCRF OUT
MIX
OSC
RF OUT
T1
AM OSC
Q10
RF
AMP
L5
AM FERRITE-ROD
ANTENNA
LPF
Q5,6
2
24
21
20 MPX
PILOT
MPX
L
15
R
7
19
LP2B
18
LP2A
11
IF REQ
16
LPF1
Q11
Q9
Q13
Q12
17
RV1
FM VCO
RF OUT
10
IF OUT
Q18(2/2)
BUFFER
Q18(1/2)
BUFFER
MIC
J501
R-CH
REV
R-CH
L-CH
FWD
FWD
REV
Q508
HP901
Q503 Q502
ISS
1
2
3
S501
RF OUT
Q514Q510
BIAS
OSC
Q501
Q504-507
Q511,512
V✤REF
T501
MIC
REG
CONT D
27
43
CONT C
28
42
41
44
3
17
15
14
L
R
23
MIC IN L
21
RADIO IN L
20
MIC IN R
18
RADIO IN R
46
MONITOR L
47
MONITOR L
35
REC MUTE
32
REC/PLAY
33
FWD/REV
Q515
34
MIC/RADIO
IC501
REC AMP
OSC
6
BIAS REG
5
BIAS
7
VCC1
8
REG
Q509
VCC2
45
B+2.5V
B+1.5V
Q513
5
1
4
2
44
12
10
IC301(1/2)
PB AMP
ANS IN
F/R SW
Q304
Q19
+2.5V VCC
14
4
11
5
10
IC302
DOLBY
CONTROL Q305 Q303
V REF
Q302
IC3
SYSTEM CONTROL
Q2
BUFFER
DOLBY VCC CTL AVLS CTL
23 54
BAND AM/FM
30
MONO/ST
68
IF IN
64
AM IN
71
RV CTL 56
IMB/GRV CTL 57
AMP CTL 58
FM IN
70
DO
66
LOCAL/DX
65
F/R CTL(PLAY)
29
REC CTL
53
DOLBY CTL
59
F/R CTL(REC)
26
RADIO/MIC
25
M DATA I/O
47
SW
13
MUTE CTL 28
AMS IN 37
BEEP 49
PRE CTL 27
BST CTL 55
R DATA OUT 31
PW SW
42
IC301(2/2)
POWER AMP
PW IN L
28
REF OUT
3
BST OUT
33
PW NF L
29
PW IN C
28
PW IN R
27
PW NF R
26
VOL
RV301
PW OUT L 20
PW OUT R 22
PW OUT C 21
AGC IN 35
MT SW
41
AMS OUT
40
BEEP
39
PRE SW
45
BST SW
43
VCC 19
BIAS 18
RF OUT 17
M/N SW
46
REG
Q1352
RF OUT
IC4
EEPROM
DI 3
DO 4
SK 2
CS 1
M CLOCK
48
CS
46
XOUT
74
XIN
75
X2
75kHz
F TUME
S902
ATS SWITCH
R TUME
B+1.5V
TAPE SWITCH
U
V
W
MOTOR
M601
CAPSTAN/REEL
U19
W3
V1
V REF
7
IN+
10
CONTROL
IC601
MOTOR
START
8
OSC
5
DR
6
S901
Q601
TAPE SPEED
ADJ
RV601
Q16,17
D4
B+1.5V
PM901
PH1
PR-20
B+2.5V
Q15(1/2)
Q15(2/2)
REV
STOP
FWD
S1
HOLD
S3
ON
OFF
F/R SW 44
PHOTO CTL 38
PHOTO IN 39
HOLD SW 41
REPEAT
RADIO
OFF
FF
PRESET+
S4 S6
MENU
S5 S8S7
SET
S9 S11
REC
S10
S2
HOLD SENS 35
BATT DET 42
KEY IN 43
IC6
REG 32 B+2.5V
1
3
4
WAKE UP 67
IC5
CONP.
ND1
LCD
COM1
COM4
1
4
S1
S18
5
22
DC/DC
CONV.
IC801
1
25
D801
Q20
OR
Ni-Cd
(NC-6WM)
1.2V
IPC 1.5V
DRY BATTERY
SIZE "AA"
(IEC DESIGNATION R6)
Q804,805
DC/DC
CONV.
T801
Q801-803
D804
D803
D802
B+2.5V
B+VD
B+1.5V
DDC2 CTL 61
DDC1 CTL 40
REMO
DATA
VCC
GND
L-CH
COM
R-CH
D201
D301
D101
D302
D303, 304
F1
B+1.5V
REMOTE
J701
•Signal Path
R DATA IN 34
F TUME 32
TAPE 52
R TUME 33
S 1/2 CTL 24
MOTOR CTL 50
OSC CTL 36
MOTOR DIR 51
PM CTL 60
16
REW
PRESET- BAND
RADIO ON/ ENTER/
COUNTER
RESET
Caution:
Pattern face side: Parts on the pattern face side seen from
(Side A) the pattern face are indicated.
Parts face side: Parts on the parts face side seen from
(Side B) the parts face are indicated.

WM-GX680/GX688
SECTION 6
DIAGRAMS
— 13 — — 14 — — 15 —
6-1. BLOCK DIAGRAM
• Waveform
Note on Printed Wiring Board:
•Y: parts extracted from the conductor side.
•b: Pattern from the side which enables seeing.
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ωand 1/4W or less unless otherwise
specified.
•f: internal component.
•C: panel designation.
•A: B+ Line.
•H: adjustment for repair.
• Power voltage is dc 1.5 V and fed with regulated dc power
supply from battery terminal.
• Voltages and waveforms are dc with respect to ground
under no-signal (detuned) conditions.
Main board (1/3)
no mark : FM/AM, TAPE STOP
( ) : FM
[ ] : AM
< > : TAPE PB
Main board (2/3), (3/3)
no mark : REC / PB
( ) : REC
[ ] : PB
• Voltages are taken with a VOM (Input impedance 10 MΩ).
Voltage variations may be noted due to normal produc-
tion tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
• Circled numbers refer to waveforms.
• Signal path.
E: PB
a: REC
F: FM
51.7kHz
1
TP32 20µsec/div
5V/div
2
IC2 !¶ VCO 5µsec/div
50mV/div
3
IC801 5PLAY BACK mode
75kHz
4
IC3 &¢ XOUT 5µsec/div
0.5V/div
5µsec/div
1V/div
14
B+1.5V
16
: FM
: PB (TAPE)
: REC (TAPE)
L-CH
1RF
AMP MIX
7
VCC
OSC
6
5
8
MIX OUT
IC1
FM RF/MIX
Q1,4
BUFFER
IF
AMP
Q7,14
L1
FM RF
D3
D2D1 L2
FM OSC
FM
FREQUENCY
COVERAGE
Q3
LOCAL/DX
CF1
10.7MHz 3IF AMP/
FM DET
X1
10.7MHz
7
IC2
IF AMP/MPX
22
AF
CF2
450KHz 6IF AMP/
AM DET
T2
AM IF
5
4
VCCRF OUT
MIX
OSC
RF OUT
T1
AM OSC
Q10
RF
AMP
L5
AM FERRITE-ROD
ANTENNA
LPF
Q5,6
2
24
21
20 MPX
PILOT
MPX
L
15
R
7
19
LP2B
18
LP2A
11
IF REQ
16
LPF1
Q11
Q9
Q13
Q12
17
RV1
FM VCO
RF OUT
10
IF OUT
Q18(2/2)
BUFFER
Q18(1/2)
BUFFER
MIC
J501
R-CH
REV
R-CH
L-CH
FWD
FWD
REV
Q508
HP901
Q503 Q502
ISS
1
2
3
S501
RF OUT
Q514Q510
BIAS
OSC
Q501
Q504-507
Q511,512
V✤REF
T501
MIC
REG
CONT D
27
43
CONT C
28
42
41
44
3
17
15
14
L
R
23
MIC IN L
21
RADIO IN L
20
MIC IN R
18
RADIO IN R
46
MONITOR L
47
MONITOR L
35
REC MUTE
32
REC/PLAY
33
FWD/REV
Q515
34
MIC/RADIO
IC501
REC AMP
OSC
6
BIAS REG
5
BIAS
7
VCC1
8
REG
Q509
VCC2
45
B+2.5V
B+1.5V
Q513
5
1
4
2
44
12
10
IC301(1/2)
PB AMP
ANS IN
F/R SW
Q304
Q19
+2.5V VCC
14
4
11
5
10
IC302
DOLBY
CONTROL Q305 Q303
V REF
Q302
IC3
SYSTEM CONTROL
Q2
BUFFER
DOLBY VCC CTL AVLS CTL
23 54
BAND AM/FM
30
MONO/ST
68
IF IN
64
AM IN
71
RV CTL 56
IMB/GRV CTL 57
AMP CTL 58
FM IN
70
DO
66
LOCAL/DX
65
F/R CTL(PLAY)
29
REC CTL
53
DOLBY CTL
59
F/R CTL(REC)
26
RADIO/MIC
25
M DATA I/O
47
SW
13
MUTE CTL 28
AMS IN 37
BEEP 49
PRE CTL 27
BST CTL 55
R DATA OUT 31
PW SW
42
IC301(2/2)
POWER AMP
PW IN L
28
REF OUT
3
BST OUT
33
PW NF L
29
PW IN C
28
PW IN R
27
PW NF R
26
VOL
RV301
PW OUT L 20
PW OUT R 22
PW OUT C 21
AGC IN 35
MT SW
41
AMS OUT
40
BEEP
39
PRE SW
45
BST SW
43
VCC 19
BIAS 18
RF OUT 17
M/N SW
46
REG
Q1352
RF OUT
IC4
EEPROM
DI 3
DO 4
SK 2
CS 1
M CLOCK
48
CS
46
XOUT
74
XIN
75
X2
75kHz
F TUME
S902
ATS SWITCH
R TUME
B+1.5V
TAPE SWITCH
U
V
W
MOTOR
M601
CAPSTAN/REEL
U19
W3
V1
V REF
7
IN+
10
CONTROL
IC601
MOTOR
START
8
OSC
5
DR
6
S901
Q601
TAPE SPEED
ADJ
RV601
Q16,17
D4
B+1.5V
PM901
PH1
PR-20
B+2.5V
Q15(1/2)
Q15(2/2)
REV
STOP
FWD
S1
HOLD
S3
ON
OFF
F/R SW 44
PHOTO CTL 38
PHOTO IN 39
HOLD SW 41
REPEAT
RADIO
OFF
FF
PRESET+
S4 S6
MENU
S5 S8S7
SET
S9 S11
REC
S10
S2
HOLD SENS 35
BATT DET 42
KEY IN 43
IC6
REG 32 B+2.5V
1
3
4
WAKE UP 67
IC5
CONP.
ND1
LCD
COM1
COM4
1
4
S1
S18
5
22
DC/DC
CONV.
IC801
1
25
D801
Q20
OR
Ni-Cd
(NC-6WM)
1.2V
IPC 1.5V
DRY BATTERY
SIZE "AA"
(IEC DESIGNATION R6)
Q804,805
DC/DC
CONV.
T801
Q801-803
D804
D803
D802
B+2.5V
B+VD
B+1.5V
DDC2 CTL 61
DDC1 CTL 40
REMO
DATA
VCC
GND
L-CH
COM
R-CH
D201
D301
D101
D302
D303, 304
F1
B+1.5V
REMOTE
J701
•Signal Path
R DATA IN 34
F TUME 32
TAPE 52
R TUME 33
S 1/2 CTL 24
MOTOR CTL 50
OSC CTL 36
MOTOR DIR 51
PM CTL 60
16
REW
PRESET- BAND
RADIO ON/ ENTER/
COUNTER
RESET
Caution:
Pattern face side: Parts on the pattern face side seen from
(Side A) the pattern face are indicated.
Parts face side: Parts on the parts face side seen from
(Side B) the parts face are indicated.

○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○○
WM-GX680/GX688
—17 — — 18 —— 16 —
6-2. SCHEMATIC DIAGRAM (1/3) •See page 15 for Waveform. •See page 23 for IC Block Diagrams.

WM-GX680/GX688
— 19 — — 20 —
6-3. SCHEMATIC DIAGRAM (2/3) • See page 15 for Waveform. • See page 23 for IC Block Diagrams.

WM-GX680/GX688
—21 — — 22 —
6-4. SCHEMATIC DIAGRAM (3/3) •See page 15 for Waveform. •See page 23 for IC Block Diagrams. •See page 29 for IC PIN FUNCTION DESCRIPTION.

—23 — — 24 —
6-5. IC BLOCK DIAGRAMS
IC302 NJM2185AV-TE2IC2 TA2022AFN-EL
IC501 LA3235WIC1 TA7371AF-EL
GND
AFC DIODE(A)
RF IN
OFC DIODE(C) MIX OUT
VCC OSC RF OUT
1 2 3 4
5678
RF
REG
MIX
OSC
891014 13 12
21 3
A-CH BLOCK
11
7654
G2 G1 V/I
WEIGHT
BIAS
CIRCUIT
+
–
+
–
GM
SUM
V+
SW
VEXT OUTA
DCA
DETA
INA
GND
IREF
VREF
OUTB
DCB
DETB
INB
B-CH BLOCK: SAME AS A-CH.
37
38
39
40
41
42
43
44
45
46
47
48
24
23
22
21
20
19
18
17
16
15
14
13
123456789101112
3536 34 33 32 31 30 29 28 27 26 25
N.C.
REF
V REF
GND
REV REC L
REV REC R
FWD REC R
FWD REC L
VCC2
MONITOR L
MONITOR R
N.C.
GND
MIC IN L
NF L
RADIO IN L
MIC IN R
NF R
RADIO IN R
MIC OUT R
MIC OUT L
REC IN L
REC IN R
N.C.
N.C. REC MUTE MIC/RADIO FWD/REV REC/PLAY CONT F CONT A
(FWD)
PLAY(REV)
(REV)
PLAY(FWD) PLAY(FWD)
(REV) (REV)
PLAY(FWD)
PLAY
REC
CONT B CONT C CONT D CONT E N.C.
N.C.
MIC REG REF
MIC REG
REC BIAS REG REF
REC BIAS REG
OSC
BASE VCC1
VCCRF
ALC
GND
N.C.
SYSTEM CONTROL
V REF
REV
REC
AMP
FWD
REC
AMP
MONITOR
AMP
DET
MIC
REGULATOR REC BIAS REGULATOR
ALC
AMP
L
ALC
AMP
R
VCC2
( ):REC
VREF
OSC
VCC
GND
IF OUT IF REG
SP OUT
1 2
FM IF IN
MIX
3 4 5
AM IF IN
QUAD
AGC
6 7 8 9
10 11 12
ROUT LOUT ST IND
13 14 15
MPX IN PILOT IN DET OUT IW SW AM RF IN
20 21 22 23 24
LPF 2A LPF 2B
18 19
LPF1 VCO
16 17
STOP
PULSE
OSC AGCMIX
FM
IF
AF
AM
IF
AM
IF
FM DET
SWITCH
AM DET
DIVIDE
DECODE
PRE
VCO090
FM
AM
PILOT ST
IND
øø
IC301 TA2123AF (EL)
IC601 MM1279XVBE
PRE A PRE B
MIX
PW B
PW A
PW C
BST
MT TC
BASE
RF IN
PW GND
OUT B
OUT C
OUT A
VCC
RF OUT
VREF OUT
BST NF
BST OUT
PW IN C
LPF
EQ A
PW NF A PW IN A
PW IN B
PW NF B
3
IN A-R
5
PRE NF-A
6
PRE OUT A
7
MTL DRV A
8
MTL DRV B
9
PRE OUT B
10
PRE NF-B
11
AMS IN
12
IN B-R
4
IN B-F
2
IN A-F
1
21
20
19
18
17
GND
16
AMS DET
15
AMS MIX
14
AMS SW
13
22
23
24
38
C-AMP SW 37
PW SW 42
MT SW 41
F/R SW 44
BST SW 43
M/N SW 46
PRE GND 47
VREF IN 48
PRE SW 45
AMS OUT 40
BEEP 39
262728293031323334
DET
36
AGC IN
35
+
–
+ –
+ –
+ –
+
–
+
–
EQ B
25
RIPPLE
FILTER
AGC
DET
BEEP
VREF
SWITCH COMPARATOR
MTL DRV
V1
PW 2
W3
GND 4
OSC 5
DR 6
VREF 7
START 8
VSP 9
IN+ 10
PV
20
U
19
PU
18
GND
17
VCC
16
FC
15
TC1
14
TC2
13
RI
12
OUT
11
MOTIVE
CONTROL
CIRCUIT
MOTIVE/
OSC MOTIVE
LOGIC SOFT SWITCH
PRE DRIVER
INVERTER
BIAS
REFERENCE
VOLTAGE
SPEED
CONTROL
CURRENT
CONTROL
OUTPUT
BIAS
+
–

WM-GX680/GX688
—25 — — 26 —
6-6. PRINTED WIRING BOARD (SIDE A)
MAIN BOARD (SIDE A)
J701
REMOTE
1-680-657-
11
(11)
S501
ISS
RV301
VOL
J501
MIC
(PLUG IN POWER)
3
2
1
REV STOP FWD
Vcc
DATA
REMO
GND
12
A
B
C
D
E
F
G
H
I
J
K
3 4 5 6 7 8 9 1011121314151617
• Semiconductor Location
Ref. No. LocationRef. No. Location Ref. No. Location Ref. No. Location
D5 B-13
D101 D-14
D201 D-14
D301 D-15
D302 B-14
D303 B-15
D304 B-13
D305 I-13
D801 E-6
D802 G-4
D803 F-4
D804 F-5
IC302 G-15
IC501 E-11
IC801 E-5
Q9 E-9
Q15 D-7
Q20 D-9
Q304 H-15
Q305 I-14
Q501 J-6
Q502 K-14
Q503 J-14
Q504 J-8
Q505 I-10
Q506 I-8
Q507 I-9
Q509 F-12
Q510 J-7
Q511 I-10
Q512 J-9
Q515 F-10
Q801 F-4
Q802 D-3
Q803 E-3
Q804 D-4
Q805 D-4

WM-GX680/GX688
—27 — — 28 —
6-7. PRINTED WIRING BOARD (SIDE B)
1-680-657- 11
(11)
MAIN
BOARD
(SIDE B)
S901
(-1)
R TUNE
(-2)
TAPE DETECT
(-1)
F TUME
(-2)
ATS
L5
AM FERRITE-ROD
ANTENNA
91
REC
HOLD
REW PRESET–
FF
PRESET+
RADIO OFF REPEAT
RADIO ON/BAND
SET
MENU
PM901
(PLUNGER)
(BATTERY CASE)
DRY BATTERY
SIZE "AA"
(IEC DESIGNATION R6)
1PC 1.5V
S902
BATTERY PACK
(Ni-Cd)
NC-6WM 1.2V
M601
(CAPSTAN/REEL MOTOR)
V
U
W
VCC
L CH
L CH
FWD
FLEXIBLE
R CH
R CH
HP901
REV
FWD
REV
1
2
3
4
5
6
7
8
9
(LIQUID CRYSTAL DISPLAY)
ENTER/COUNTER
RESET
S2
ON OFF
12
A
B
C
D
E
F
G
H
I
J
K
3 4 5 6 7 8 9 101112131415
•Semiconductor Location
Ref. No. LocationRef. No. Location
D1 B-5
D2 C-5
D3 H-4
D4 D-6
D6 E-3
IC1 C-4
IC2 F-5
IC3 E-9
IC4 D-10
Ref. No. Location Ref. No. Location
IC5 E-10
IC6 E-10
IC301 H-9
IC601 F-11
Q1 E-7
Q2 E-7
Q3 C-3
Q4 C-5
Q5 E-6
Q6 E-6
Q7 C-3
Q8 D-8
Q10 D-3
Q11 F-6
Q12 G-7
Q13 G-3
Q14 C-3
Q16 D-5
Q17 D-5
Q18 H-6
Q19 H-7
Q301 G-11
Q302 H-7
Q303 H-7
Q508 I-2
Q513 G-7
Q514 I-8
Q601 E-11