Read Sharp QT-120H (serv.man2) Service Manual online
QT-120H
– 4 –
ADJUSTMENT
Figure 4 VCO FREQUENCY TEST CIRCUIT
TUNER SECTION
fL: Low-range frequency
fH: High-renge frequency
fH: High-renge frequency
Specified value
Instrument Connection
VR101
76 kHz
±
200 Hz
Pin 13, Pin 21 and ground
of IC102
• FM IF/RF
Specified Value/
Adjusting
Point
• AM IF/RF
Test Stage
Specified Value/
Adjusting
Point
Instrument
Connection
Test Stage
IF
T101
Input: FM Antenna
Detection
T102
Output:Pin 9 of IC102
Band
fL: L103
Input: Antenna
Coverage
fH: TC2
Output: Headphone Socket
Tracking
fL(88 MHz): L102
(Load resistance:
fH(108 MHz): TC1
32 ohms)
Specified Value
Play: TW-2412
Over 120 g
MECHANISM SECTION
• Driving Force Check
Specified Value
• Torque Check
Play: TW-2111
25 to 65 g.cm
Fast forward: TW-2231
60 to 130 g.cm
Rewind: TW-2231
60 to 130 g.cm
• Head Azimuth
MTT-114
Output: Speaker Terminal
(Load resistance:
3 ohms)
Instrument Connection
• Tape Speed
Instrument
Connection
Normal
MTT-111
3,000
±
Speaker
Speed
30 Hz
terminal
(Load
resistance:
(Load
resistance:
6 ohms)
* Open the cassette holder, and load the test tape directly into
the mechanism. (Do not load the tape into the cassette
holder.)
holder.)
Specified Value
Beat Cancel
A: 80 kHz + 10 kHz/ – 6kHz
B: – 3
B: – 3
±
1 kHz for A
C: – 5
±
2 kHz for A
DECK SECTION
• Bias Oscillation
Torque Meter
Torque Meter
Test Tape
Specified Value
Test Tape
• Beat Cancel Switch: A
T201
80 kHz + 10 kHz
Pin 2 of CNP201
– 6 kHz
Adjustment Point
Specified value
Instrument
Connection
IF
T103
MW Band
fL: L107
Coverage
fH: TC4
MW Tracking fL(600 kHz): L104
fH(1,400 kHz): TC3
LW Band
fL: L108
Coverage
fH: TC103
LW
fL(170 kHz): L105
Tracking
fH(270 kHz): TC102
Input: Antenna
Output: Pin 9 of IC102
Output: Pin 9 of IC102
Input: Antenna
Output: Headphone Socket
(Load resistance
32 ohms)
32 ohms)
Adjustment
Point
• VCO Frequency
Note:
After preparing the test circuit shown in Fig. 4, connect the Pin
13, Pin 21 and ground of the IC102 with the test circuit, and
measure the value.
After preparing the test circuit shown in Fig. 4, connect the Pin
13, Pin 21 and ground of the IC102 with the test circuit, and
measure the value.
10 pF
1M ohm
10K ohm
0.1
˚
F
TO FREQUENCY
COUNTER
COUNTER
Pin 13 of IC102
Pin 21 of IC102
FET: 2SK212
(or Other 2SK Type FET.)
(or Other 2SK Type FET.)
G
D
S
Instrument
Connection
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