Mechanical Adjustments; Electrical Adjustments - Sony HCD-EC68 Service Manual

HCD-EC68/EC78
SECTION 5

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 demag-
netizer. (Do not bring the head magnetizer close to the erase
head.)
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, appiy suitable locking compound to the
parts adjusted.
5. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
•
Torque Measurement
Mode Torque Meter
FWD CQ-102AS
FWD
CQ-102C
Back Tension
FF CQ-201AS
REV CQ-201B
•
Tape Tension Measurement
Mode Tension Meter
FWD CQ-403A
18
Meter Reading
2.0 – 8.0 mN • m
(20 to 80 g • cm)
(0.28 – 1.12 oz • inch)
0.15 – 0.6 mN • m
(1.5 to 6 g • cm)
(0.021 – 0.083 oz • inch)
5 – 17.7 mN • m
(50 to 177 g • cm)
(0.7 – 2.48 oz • inch)
5 – 17.7 mN • m
(50 to 177 g • cm)
(0.7 – 2.48 oz • inch)
Meter Reading
more than 80 g
(more than 2.82 oz)
SECTION 6

ELECTRICAL ADJUSTMENTS

DECK SECTION
(EXCEPT EC68: UK model)
1. Demagnetize the record/playback head with a head demagne-
tizer.
2. Do not use a magnetized screwdriver for the adjustments.
TEST TAPE
Tape Signal
P-4-A063 6.3 kHz, -10 dB
RECORD/PLAYBACK HEAD AZIMUTH ADJUSTMENT
Note: Perform this adjustments for both decks.
Procedure:
1. Mode: Playback
test tape
JACK board
P-4-A063
PHONES jack
(6.3 kHz, −10 dB)
(J492)
set
2. Turn the adjustment screw and check output peaks. If the peaks
do not match for L-CH and R-CH, turn the adjustment screw
so that outputs match within 1dB of peak.
within
L-CH
1dB
peak
Output
level
R-CH
peak
Screw
position
L-CH
peak
3. Mode: Playback
test tape
JACK board
P-4-A063
PHONES jack
(6.3 kHz, −10 dB)
(J492)
set
waveform of oscilloscope
in phase 45° 90° 135° 180°
good
4. After the adjustments, apply suitable locking compound to the
pats adjusted.
0 dB = 0.775V
Used for
Azimuth Adjustment
level meter
+
–
within
1dB
Screw
position
R-CH
peak
oscilloscope
V H
wrong