Sony CFS-B31 Service Manual

SECTION 3
MECHANICAL ADJUSTMENTS
PRECAUTION
1. Clean the following parts with a denatured-alcohol-
moistened swab :
record/playback head pinch roller
erase head rubber belts
capstan idlers
2. Demagnetize the record/playback head with a head
demagnetizer. (Do not bring the head demagnetizer close to
the erase head.)
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, apply suitable locking compound to
the parts adjusted. ;
5. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
1. Torque Measurement
| Mode Torque Meter Meter Reading
30 — 70 g*cm
Playback COA (0.42 — 0.97 oz « inch)
Pee ; C0-102C 1.5—5.5 g*cm
aceSIOu 2 (0.021 — 0.076 oz « inch)
60 — 130 g + cm
-201B '
2. Tape Tension Measurement
| Mode | Tension Meter Meter Reading
CQ-403A more than 100g (3.53 oz)
SECTION 4
ELECTRICAL ADJUSTMENTS
TAPE SECTION
1. The adjustments should be performed in the order given in
the service manual. (As a general rule. playback circuit
adjustment should be completed before performing
recording circuit adjustment.)
2. The adjustments should be performed for both L-CH and R-
CH unless otherwise indicated.
« Switch location
FUNCTION sjiscaiveissciteneare TAPE
VOLUME iccsusseressvsainitoatonne MAX
TON Be vesiteeiccretaneseatssatetnentvans HIGH
Standard Output Level
SP OUT
Output level 0.775V (0 dB)
Test Tape
| Type | Sonat | Useditor
WS-48B 3 kHz, 0 dB Tape Speed Adjustment
P-4-A063 6.3 kHz, -10 dB Head azimuth adjustment
0 dB =0.775 V
Tape speed adjustment
Procedure :
Mode : playback speed checker
LFM-30 or
test tape digital frequency
WS-48B
counter
(3 kHz, 0 dB) 32Q
phones jack
Adjustment Values :
Speed checker Digital frequency counter
Frequency difference between the beginning and the end of the
tape should be within 1.5% (45Hz).
Adjustment Location :
tape speed adjustment
countrol inside motor

Sony CFS-B31 Specifications

General

Brand	Sony
Model	CFS-B31
Category	Cassette Player
Language	English