Sharp QT-CD111, Service Manual

Page: 6 / 32

QT-CD111/111C
– 6 –
MECHANISM SECTION
• Driving Force Check
PLAY: TW-2412 Over 120 g
Torque Meter
Specified Value
• Torque Check
Torque Meter Specified Value
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
• Tape Speed
MTT-111 In motor 3,000
±
90 Hz Output: Speaker
Teaminal
(CNP201 Load
resistance: 8 ohms)
Instrument
Connection
Specified
Value
Test
Tape
TAPE SECTION
Position of each switch or control
Volume control Max
Function switch Tape/Power Off
X-BASS On
• Bias Oscillation
Adjustment Point
• Playback Amplifier Sensitivity Check
Instrument Connection
Test Tape
MTT-118 1.8 V
±
3 dB Speaker Terminal
(Load resistance: 8 ohms)
Specified Value
ADJUSTMENT
TUNER SECTION
fL: Low-range frequency
fH: High-range frequency
• FM IF/RF
IF T1
Detection T2
Band Coverage fL: L2
fH: TC2
Tracking 88.0 MHz: L1
108.0 MHz: TC1
Test Stage
Specified
Value/Adjusting
Point
Instrument
Connection
Input: Pin 1 of IC1
Output: Pin 17 of IC2
Iuput: Antenna
Output: Speaker
Terminal (CNP201
Load resistance: 8
ohms)
• AM IF/RF
IF T3 Input: Antenna
Output: Pin 19 of IC2
Band Coverage fL: L4 Input: Antenna
fH: TC4 Output: Speaker
Tracking 600 kHz: L3 Terminal (CNP201
1,400 kHz: TC3 Load resistance: 8
ohms)
Test Stage Specified
Value/Adjusting
Point
Instrument
Connection
• VCO Frequency
Specified
Value
Instrument
Connection
VR1 76 kHz
±
200 Hz Pin 13, pin 21 and
ground of IC2
Adjusting Point
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
D
G
S
10 kohm
TO FREQUENCY
COUNTER
FET : 2SK19 or 2SK54
Figure 6-1 VCO FREQUENCY TEST CIRCUIT
Figure 6-2 ADJUSTMENT POINTS
• Head Azimuth
Torque Meter
Specified Value
MTT-114 Output: Speaker Terminal
(CNP201 Load resistance: 8 ohms)
Adjusting
Point
Specified Value
Instrument
Connection
L301 82 kHz
±
6 kHz Pin 2 of CNP201
– 6 kHz
AM
TRACKING
fL
FM
DETECTION
T2
VCO
VR1
IC2
IC1
T1
FM IF
AM IF
L4
TC4
TC2
TC1
TC3
AM
TRACKING
fH
L1
L2
AM BAND
COVERAGE
FM
TRACKING
FM BAND
COVERAGE
fH fL fH fL fH fL
T3
L3
AM BAR ANTENNA
FM ROD ATENNA
MAIN PWB
1
1
13
17
19
21