Sony XR-1790 Service Manual ▷ View online
– 9 –
MAIN BOARD, HEAT SINK
BRACKET (MD)
4
five screws
(PTT2.6
(PTT2.6
×
8)
1
two screws
(PTT2.6
(PTT2.6
×
6)
5
heat sink
2
two screws
(ground point)
(ground point)
3
MAIN board
1
two screws
(P2.6
(P2.6
×
4)
1
two screws
(P2.6
(P2.6
×
4)
2
bracket (MD)
– 10 –
MOTOR ASS’Y (CAPSTAN/REEL) (M901)
CASSETTE HANGER (X)
1
two screws
(P2
(P2
×
3)
4
motor ass’y (CAPSTAN/REEL)
(M901)
(M901)
3
belt
2
belt
1
Remove the claw toward
direction.
direction.
2
Remove the return link
toward direction.
toward direction.
5
cassette hanger (x)
3
boss
3
boss
4
two claws
1
Remove the claw toward
direction.
direction.
– 11 –
CASSETTE HOLDER (X)
A
1
Push an arrow
A
part.
2
Removal the cassette holder (x)
to direction of the arrow.
to direction of the arrow.
– 12 –
SECTION 3
MECHANICAL ADJUSTMENTS
Mode
Tension Meter
Meter Reading
Forward
CQ-403A
more than 60 g
Reverse
CQ-403R
(more than 2.12 oz)
• Tape Tension Measurement
1. Clean the following parts with a denatured-alcohol-moistened
swab:
playback head
pinch roller
rubber belt
capstan
idler
2. Demagnetize the playback head with a head demagnetizer.
3. Do not use a magnetized screwdriver for the adjustments.
4. The adjustments should be performed with the power supply
3. Do not use a magnetized screwdriver for the adjustments.
4. The adjustments should be performed with the power supply
voltage (14.4 V) unless otherwise noted.
• Torque Measurement
Mode
Torque Meter
Meter Reading
Forward
CQ-102C
25 – 55 g•cm
(0.35 – 0.76 oz•inch)
Forward
CQ-102C
1.5 – 4 g•cm
Back Tension
(0.02 – 0.06 oz•inch)
Reverse
CQ-102RC
25 – 55 g•cm
(0.35 – 0.76 oz•inch)
Reverse
CQ-102RC
1.5 – 4 g•cm
Back Tension
(0.02 – 0.06 oz•inch)
FF, REW
CQ-201B
50 – 150 g•cm
(0.69 – 2.08 oz•inch)
SECTION 4
ELECTRICAL ADJUSTMENTS
TAPE DECK SECTION
0 dB= 0.775 V
1. The adjustments should be performed in the order given in
this service manual.
2. The adjustments should be performed for both L-CH and
R-CH.
Test Tape
PB Head Azimuth Adjustment
Procedure:
1. Put the set into the FWD PB mode.
1. Put the set into the FWD PB mode.
2. Turn the screw and check the output peak value. Adjust the
screw so that the peak value in channels L and R coincides
within 2 dB.
within 2 dB.
3. Check the phase in the FWD PB mode.
Type
Signal
Used for
P-4-A063
6.3 kHz, –10 dB
head azimuth adjustment
WS-48A
3 kHz, 0 dB
tape speed adjustment
screw
position
position
L-CH
peak
peak
within
2 dB
2 dB
output
level
level
L-CH
peak
peak
R-CH
peak
peak
within
2 dB
2 dB
angle
R-CH
peak
peak
test tape
P-4-A063
(6.3 kHz, –10 dB)
P-4-A063
(6.3 kHz, –10 dB)
L-CH
R-CH
speaker out terminal
oscilloscope
V
H
+ +
–
–
Screen pattern
in phase
good
wrong
45
°
90
°
135
°
180
°
4
Ω
4
Ω
set
level
meter
test tape
P-4-A063
(6.3 kHz, –10 dB)
P-4-A063
(6.3 kHz, –10 dB)
set
speaker out terminal
4
Ω
+
–
–
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