Sony wm ex 55 service manual

Page 2

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SECTION 1
SERVICING NOTE

This set detects reel rotation by PH701 (photo
sensor). Reel rotation cannot be detected when the
main board is removed, because PH701 is mounted on
the main board. As a result, the auto-off circuit and
tape end detection will misoperate. And, up and down
of head and power supply of playback circuit cannot
operate when the main board is removed, because S
703 (NR switch) is mounted to the main board (S703
is linked to on and off of the plunger solenoid.)
Therefore, operation check of the mechanism deck
and voltage check can be performed by the method
shown below.

- AUDIO Board (Side A) -

FF/REW mode
1) Switch position S703 : STOP (Center)
2) Apply the square wave signal to the PH701.
3) Press the « or » key.

PLAY mode
1) Switch position S703 : STOP (Center)
2) Apply the square wave signal to the PH701.
3) Press the > key.
4) Turn on S703 a few seconds later.

SQUARE WAVE

OSCILLATOR W

G)

L___J SQUARE WAVE
20 Hz

0 dB (1 V) '

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noun-gym

Ell-33