Adjustment; Tuner Section - Sharp CD-C492 Service Manual

CD-C492/492C
MECHANISM SECTION
• Driving Force Check
Torque Meter
Play: TW-2412
• Torque Check
Torque Meter
Play: TW-2111 30 to 60 g. cm
Fast forward: TW-2231 —
Rewind: TW-2231 —
• Tape Speed
Adjusting
Test Tape
Point
Normal MTT-111 VRM1
speed

TUNER SECTION

fL: Low-range frequency
fH: High-renge frequency
• AM IF/RF
Signal generator: 400 Hz, 30%, AM modulated
Test Stage Frequency Frequency
Display
IF 450 kHz 1,720 kHz
Band — 530 kHz
Coverage
Tracking 990 kHz 990 kHz
*1. Input: Antenna, Output: TP302
*2. Input: Antenna, Output: TP301
TAPE MECHANISM PWB
VRM1
SWM1
TAPE
FAS
SPEED
SW
Figure 16-1

ADJUSTMENT

Specified Value
Tape 1: Over 80 g
Tape 2: Over 80 g
Specified Value
Tape 1
Tape 2
30 to 100 g.cm
50 to 100 g.cm
50 to 100 g.cm
Specified Instrument
Value Connection
3,000 ± Speaker
30 Hz terminal
(Load
resistance:
8 ohms)
Setting/ Instrument
Adjusting
Connection
Parts
T351 *1
(fL): T302 *2
1.1 ± 0.1 V
(fL): T302 *1
TUNER PWB
AM IF
Q342
B C E
13
TP302
VR351
VCO
FM
DETECTION
Figure 16-3 ADJUSTMENT POINTS
• FM RF
Signal generator: 1 kHz, 75 kHz dev., FM modulated
Test Stage Frequency Frequency
Band —
Coverage
RF 98.00 MHz 98.00 MHz L302
(10-30 dB)
*1. Input: Antenna, Output: TP302
*2. Input: Antenna, Output: TP301
• Detection
Signal generator: 10.7 MHz, FM sweep generator
Test Frequency
Stage
Detection 10.7 MHz
IF 10.7 MHz
• VCO Frequency
Frequency Frequency
Display
98.00 MHz 98.00 MHz
(60 dB)
* Adjust for 76 kHz ± 200 Hz.
Notes:
After preparing the test circuit shown in Fig 16-2, connect the
Pin 13 , Pin 21 and ground of the IC303 with test circuit, and
measure the Value.
At this time, apply a standard unmodulated signal input and
adjust the VCO.
Pin 21 of IC303
Pin 13 of IC303
D
G
S
IC302
20
TP301
L303
T351
FM BAND
COVERAGE fL
1
IC303
21 T304
T352
AM BAND
COVERAGE fL
– 16 –
Serring/
Display Adjusting
Point
87.50 MHz L303(fL):
3.7 V ± 0.1 V
Frequency Adjusting Instrument
Display Parts
Connection
98.00 MHz T352 Input: Pin 1 of
IC303
Output: TP302
98.00 MHz T301(Turn Input: Pin 1 of
the core of IC301
transformer Output: TP302
T301 fully
counter-
clookwise.)
Adjusting Instrument
Parts Connection
VR351* Pin 13, Pin 21
and ground
of IC303
FET : 2SK19 or 2SK54
TO FREQUENCY
10 kΩ
Figure 16-2
SO301
ANTENNA
IC301
TERMINAL
1
L302
T301
FM 75 ohms
FM RF
FM IF
GND
AM
T302
AM
TRACKING fL
Instrument
Connection
*1
*2
COUNTER