Adjustment - Sharp QT-CD121 Service Manual

QT-CD121
MECHANISM SECTION
• Driving Force Check
Torque Meter
PLAY: TW-2412 Over 120 g
• Torque Check
Torque Meter
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
Torque Meter
MTT-114 Output: Speaker Terminal
(CNP201 Load resistance: 8 ohms)
• Tape Speed
Adjusting
Test Specified
Point
Tape
3,000 ± 90 Hz
MTT-111 In motor
TAPE SECTION
Position of each switch or control
Volume control
Function switch
X-BASS
• Bias Oscillation
Adjustment Point Specified Value
82 kHz ± 6 kHz
L301
• Playback Amplifier Sensitivity Check
Test Tape Specified Value
1.8 V ± 3 dB
MTT-118
MAIN PWB
AM
TRACKING
fL
fH fL
AM BAND
COVERAGE
Figure 6-2 ADJUSTMENT POINTS

ADJUSTMENT

Specified Value
Specified Value
Specified Value
Instrument
Value Connection
Output: Speaker
Teaminal
(CNP201 Load
resistance: 8 ohms)
Max
Tape/Power Off
On
Instrument
Connection
Pin 2 of CNP201
Instrument Connection
Speaker Terminal
(Load resistance: 8 ohms)
FM ROD ATENNA
VR1
VCO
13
17
IC2 T3
T2
19
FM
DETECTION 21
1
L4
AM IF
L2
T1
IC1
TC4
TC2
TC3
FM IF
TC1
L1
AM 1
TRACKING
fH
fH fL fH fL
FM
FM BAND
TRACKING
COVERAGE
TUNER SECTION
fL: Low-range frequency
fH: High-range frequency
• FM IF/RF
Test Stage
Value/Adjusting
IF T1
Detection T2
Band Coverage fL: L2
fH: TC2
Tracking 88.0 MHz: L1
108.0 MHz: TC1
• AM IF/RF
Test Stage
Value/Adjusting
IF T3
Band Coverage fL: L4
fH: TC4
Tracking 600 kHz: L3
1,400 kHz: TC3
• VCO Frequency
Adjusting Point
76 kHz ± 200 Hz
VR1
Note:
After preparing the test circuit shown in Fig. 6-1, connect the
Pin 13, Pin 21 and ground of the IC2 with the test circuit, and
measure the value. At this time, apply a standard unmodulated
signal input and adjust the VCO.
Pin 13 of IC2 Pin 21 of IC2
FET : 2SK19 or 2SK54
D
G
S
10 kohm
Figure 6-1 VCO FREQUENCY TEST CIRCUIT
– 6 –
Specified Instrument
Connection
Point
Input: Pin 1 of IC1
Output: Pin 17 of IC2
Iuput: Antenna
Output: Speaker
Terminal (CNP201
Load resistance: 8
ohms)
Specified Instrument
Connection
Point
Input: Antenna
Output: Pin 19 of IC2
Input: Antenna
Output: Speaker
Terminal (CNP201
Load resistance: 8
ohms)
Specified Instrument
Value Connection
Pin 13, pin 21 and
ground of IC2
TO FREQUENCY
COUNTER