SONY M640V
Service Manual

M-640V/645V/647V SECTION 3 MECHANICAL ADJUSTMENTS
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. 3. Do not use a magnetized screwdriver for the adjustments. 4. The adjustments should be performed with the rated power supply voltage unless otherwise noted. Power supply voltage: 3 Vdc TAPE SPEED switch : 2.4 cm Torque Measurement
Mode Forward Fast Forward Torque Meter CQ-103M CQ-201M Meter Reading 0.49 � 1.27 mN � m (5 � 13 g � cm) (0.07 � 0.180 oz � inch) more than 2.95 mN � m (more than 30 g � cm) (more than 0.42 oz � inch) Rewind CQ-201M more than 2.95 mN � m (more than 30 g � cm) (more than 0.42 oz � inch)

SECTION 4 ELECTRICAL ADJUSTMENTS
Specified voltage: 3 V (DC) Test Tape
Type S-2-A030 WS-24 WS-12 Signal 3 kHz, � 20 dB 3 kHz, � 10 dB Used for Head Azimuth Adjustment Tape Speed Adjustment Tape Speed (cm/s) 2.4 2.4 1.2

Record/Playback/Erase Head Azimuth Adjustment
Setting: [VOL] control : mechanical mid [TAPE SPEED] switch : 2.4 cm/s [VOR] switch : OFF Procedure: 1. Mode: Playback
test tape S-2-A030 (3 kHz, �20 dB) set

level meter 16 � + �

Tape Tension Measurement
Mode Forward Tension Meter CQ-403M Meter Reading more than 20 g (more than 0.28 oz)

[EAR] jack (J101)

2. Turn the head azimuth adjustment screw to obtain the maximum reading on level meter.
Note: Several peaks may appear, but the maximum.

Adjustment Location: First remove the cover (AZ).
Remove the cover (AZ).

head azimuth adjustment screw

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