Sony XR-3750 / XR-3758 / XR-3759 / XR-7750 / XR-C350 / XRS-888 Service Manual ▷ View online
– 17 –
GEAR (LDG-FT)
2 guide (C)
1 three claws
GUIDE (C)
4 Align hole in the gear (LDG-D) with
¢ mark on the lever (LDG-A).
gear (LDG-FB)
hole
gear (LDG-D)
gear (LDG-A)
3 Move the lever (LDG-B)
in the arrow direction.
1 gear (LDG-A)
2 tension spring (lever LDG)
5 gear (LDG-FT)
6 polyethylene washer
– 18 –
SECTION 5
ELECTRICAL ADJUSTMENTS
TEST MODE
This set have the test mode function. In the test mode, FM Auto
Scan/Stop Level and AM (MW) Auto Scan/Stop Level adjustments
can be performed easier than it in ordinary procedure.
Scan/Stop Level and AM (MW) Auto Scan/Stop Level adjustments
can be performed easier than it in ordinary procedure.
<Set the Test Mode>
1. Set the “OFF” mode.
2. Push the preset 4 button.
3. Push the preset 5 button.
4. Press the preset 1 button for more than two seconds.
5. Then the display indicates all lights, the test mode is set.
1. Set the “OFF” mode.
2. Push the preset 4 button.
3. Push the preset 5 button.
4. Press the preset 1 button for more than two seconds.
5. Then the display indicates all lights, the test mode is set.
<Release the Test mode>
1. Push the “OFF” button.
1. Push the “OFF” button.
SECTION 4
MECHANICAL ADJUSTMENTS
1. Clean the following parts with a denatured-alcohol-moistened
swab:
playback head
pinch roller
erase head
rubber belts
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
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
Torqu Meter
Meter Reading
Forward
CQ-102C
35–65 g•cm
(0.49–0.90 oz•inch)
Forward
CQ-102C
0.5–5.0 g•cm
Back Tension
(0.01–0.07 oz•inch)
Reverse
CQ-102RC
35–65 g•cm
(0.49–0.90 oz•inch)
Reverse
CA-102RC
0.5–5.0 g•cm
Back Tension
(0.01–0.07 oz•inch)
FF, REW
CQ-201B
60–200 g•cm
(0.83–2.78 oz•inch)
Mode
Torqu Meter
Meter Reading
Forward
CQ-403A
more than 60 g
Reverse
CQ-403R
(more than 2.12 oz)
•
Tape Tension Measurement
– 19 –
TUNER SECTION
0 dB=1 µV
Cautions during repair
When the tuner unit is defective, replace it by a new one be-
cause its internal block is difficult to repair.
cause its internal block is difficult to repair.
FM Auto Scan/Stop Level Adjustment
Setting:
Setting:
SOURCE button: FM
See the adjustment location from on page 21 for the
adjustment.
adjustment.
0 dB=0.775 V
TAPE DECK SECTION
Tape Speed Adjustment
Procedure:
1. Put the set into the FWD PB mode.
Procedure:
1. Put the set into the FWD PB mode.
Speed checker
Frequency counter
–1.5 to +2.5%
2,955 to 3,075 Hz
Specification: Constant speed
Adjustment Location: See page 21.
FM RF signal
generator
Carrier frequency : 98.0 MHz
Output level
Output level
: 22 dB (12.6
µ
V)
Mode
: mono
Modulation
: 1 kHz, 22.5 kHz deviation (30%)
0.01
µ
F
set
antenna jack (J1)
Procedure:
1. Set to the test mode. (See page 18).
2. Push the SOURCE button and set to FM.
1. Set to the test mode. (See page 18).
2. Push the SOURCE button and set to FM.
Display
3. Push the preset 3 button.
Display
4. Adjust with the volume RV2 on TU1 so that the “FM” indica-
tion turns to “FMI” indication on the display window.
But, in case of already indicated “FMI”, turn the RV2 so that
put out light “I” indication and adjustment.
But, in case of already indicated “FMI”, turn the RV2 so that
put out light “I” indication and adjustment.
Display
set
+
–
test tape
WS-48A
(3 kHz, 0 dB)
WS-48A
(3 kHz, 0 dB)
LINE OUT (XR-C350)
SPEAKER OUT (XR-3750)
SPEAKER OUT (XR-3750)
10 k
Ω
(XR-C350)
4
Ω
(XR-3750)
speed checker
or
frequency counter
Adjustment Location: See page 21.
FM
98.0
SHUF1
FM
98.0
3
SHUF1
– 20 –
FM Stereo Separation Adjustment
Setting:
Setting:
SOURCE button: FM
FM RF signal
generator
Carrier frequency : 98.0 MHz
Output level
Output level
: 70 dB (3.2 mV)
Mode
: stereo
Modulation
: main: 1 kHz, 33.75 kHz deviation (45%)
sub: 1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot: 7.5 kHz deviation (10%)
sub: 1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot: 7.5 kHz deviation (10%)
0.01
µ
F
set
antenna jack (J1)
+
–
–
LINE OUT (XR-C350)
SPEAKER OUT (XR-3750)
SPEAKER OUT (XR-3750)
level meter
10 k
Ω
(XR-C350)
4
Ω
(XR-3750)
AM (MW) Auto Scan/Stop Level Adjustment
Setting:
Setting:
SOURCE and MODE button: MW
AM RF signal
generator
Carrier frequency : 999 kHz
30% amplitude
modulation by
1 kHz signal
Output level
30% amplitude
modulation by
1 kHz signal
Output level
: 33 dB (44.7
µ
V)
(50
Ω
)
set
AM dummy antenna
30
Ω
15 pF
65 pF
antenna jack (J1)
Procedure:
1. Set to the test mode. (See page 18.)
2. Push the SOURCE button and set to FM.
3. Push the MODE button and set to MW.
1. Set to the test mode. (See page 18.)
2. Push the SOURCE button and set to FM.
3. Push the MODE button and set to MW.
Display
5. Adjust with the volume RV1 on TU1 so that the “MW” indi-
cation turns to “MWI” indication on the display window.
But, in case of already indicated “MWI”, turn the RV1 so that
put out light “I” indication and adjustment.
But, in case of already indicated “MWI”, turn the RV1 so that
put out light “I” indication and adjustment.
Display
4. Push the preset 3 button.
Display
Adjustment Location: See page 21.
Procedure:
FM Stereo
Level meter
Level meter
signal generator
connection
reading (dB)
output channel
L-CH
L-CH
A
B
R-CH
L-CH
Adjust RV4 on TU1
for minimum reading.
R-CH
R-CH
C
D
L-CH
R-CH
Adjust RV4 on TU1
for minimum reading.
L-CH Stereo separation: A-B
R-CH Stereo separation: C-D
The separations of both channels should be equal.
R-CH Stereo separation: C-D
The separations of both channels should be equal.
Specification: Separation more than 28dB
Adjustment Location: See page 21.
INTRO
999
3
SHUF1
MW
INTRO
999
3
SHUF1
MW
INTRO
999
SHUF1
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