Mechanical Adjustments; Electrical Adjustments; Tape Deck Section; Tuner Section - Sony XR-4890 Service Manual

SECTION 4

MECHANICAL ADJUSTMENTS

1. Clean the following parts with a denatured-alcohol-moistene
swab:
playback head pinch roller
rubber belt capstan
idlers
2. Demagnetize the playback head with a head demagnetizer.
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 power supply
voltage unless otherwise noted.
• Torque Measurement
Mode Torque Meter
Forward CQ-102C
Forward
CQ-102C
Back Tension
Reverse CQ-102RC
Reverse
CA-102RC
Back Tension
FF, REW CQ-201B
• Tape Tension Measurement
Mode Tension Meter
Forward CQ-403A
Reverse CQ-403R

TAPE DECK SECTION

Tape Speed Adjustment
Setting:
Meter Reading
Procedure:
30 – 65 g•cm
(0.42 – 0.90 oz·inch)
1. Put the set into the PB mode.
2. Adjust adjustment resistor for inside capstan motor so that the
0.5 – 4.5 g•cm
(0.01 – 0.06 oz·inch)
30 – 65 g•cm
(0.42 – 0.90 oz·inch)
Specification: Constant speed
0.5 – 4.5 g•cm
(0.01 – 0.06 oz·inch)
60 – 200 g•cm
(0.83 – 2.78 oz·inch)

TUNER SECTION

Meter Reading
The tuner section has no adjustment.
more than 90 g
(more than 3.18 oz)
more than 90 g
Adjustment Location:
(more than 3.18 oz)
– SET UPPER VIEW –
Tape Speed Adjustment
– 14 –
SECTION 5

ELECTRICAL ADJUSTMENTS

test tape
WS-48A
(3 kHz, 0 dB)
set
LINE OUT
reading on the speed checker or frequency counter becomes in
specification.
Speed checker
–1.5 to +2.5%
0 dB=0.775 V
speed checker
or
frequency counter
10 k Ω
–
+
Frequency counter
2,955 to 3,075 Hz
0 dB=1 µV
TU 1