Servicing Note - Sony WM-EX422 Service Manual

This set detects the rotation of the idler gear (A) (side S) using the
photo reflector (PH751). The PH751 is mounted on the MAIN
board, therefore the idler gear (A) (side S) cannot be detected with
the MAIN board removed. As a result, the motor (M601) cannot
be controlled, causing malfunction.
Further, the MD switch (S601) is also mounted on the MAIN board,
and with the board removed, the mechanism position cannot be
detected and the operation is not changed over.
Therefore, when the voltage check is executed with the MAIN
board removed, follow the procedure provided below.
1. Setting
1) Refer to "3. DISASSEMBLY", and remove the MAIN board.
2) Connect the MAIN board to the motor (M601) using jumper
wires. These can be connected easily with the use of the
extension tool (Part No. 1-769-143-11) (ten in one set).
3) Connect the AF oscillator to the TP52 and the BT401 (BATT–
).
4) Supply 1.5 V to the battery terminals using the regulated power
supply.
2. Preset state
To set the PLAY, FF, REW modes, the preset state must be set.
1) Check that the slider (NRA) and the MD switch (S601) are set
to the center position. If not, set the preset state as follow.
2) Move the MD switch (S601) to the side, which the slider (NRA)
is facing.
3) The slider (NRA) will move when the regulated power supply
switch is set to OFF once and then set to ON. Move the MD
switch (S601) according to this timing and set to the center
position.
— MAIN Board (Component Side) —
SECTION 1
SERVICING NOTES
3. FF, REW modes
1) Check that the preset state is set.
2) Input the square wave or sine wave to the TP52 and the BT401
(BATT–).
3) Press the
4. PLAY mode
1) Check that the preset state is set.
2) Input the square wave to the TP52 and the BT401 (BATT–).
3) Press the Y button will move the slider (NRA) once towards
the side REV and then to the side FWD. Move the MD switch
(S601) according to this timing will set the PLAY mode (side
FWD). Press the Y button another time for a second and
move the MD switch (S601) according to the movement of
the slider (NRA) will set the PLAY mode (side REV).
If the above fails, perform from preset again.
Note 1:
When using headphones, the timing for move the
Note 2:
switch (S601) can be determined from the beep sound.
— MAIN Board (Conductor Side) —
[FF] [REW]
button or button .
RVS
REW
FF
FWD
connect to themotor (M601)
WM-EX422
MD
battery terminal #
AF oscillator
square wave
2 Hz, 2 VdB
2Vp-p
battery
terminal 3
3