Read Sharp VC-MH742HM (serv.man20) Service Manual online
30
VC-M332HM
VC-MH742HM
VC-MH742HM
Measuring
instrument
instrument
Mode
Test point
Colour TV monitor
DV voltmeter
DV voltmeter
RF signal at 40CH(by VHF
signal generator)
signal generator)
Pin(2)(Sig.) of P1501.
Pin(4)(GND.) of P1501.
Pin(4)(GND.) of P1501.
Control
R1626 RF AGC control
Specification
3.9
±
0.2V
1.Receive the 40 channel signal (colour bar signal at
87.5% modulated.) at input field strength: 56dB
87.5% modulated.) at input field strength: 56dB
µ
of
antenna terminal.
2.Connect a DC voltmeter to test point shown in table.
3.Look the voltmerter and adjust R1626 so that the
voltage be specified.
2.Connect a DC voltmeter to test point shown in table.
3.Look the voltmerter and adjust R1626 so that the
voltage be specified.
Measuring
instrument
instrument
Mode
Test point
Colour TV monitor
DV voltmeter
DV voltmeter
Control
T1601 VCO control
Specification
2.5
±
0.2V
RF signal at 40CH(by VHF
signal generator)
signal generator)
Pin(1)(Sig.) of P1501.
Pin(4)(GND.) of P1501.
Pin(4)(GND.) of P1501.
ADJUSTMENT OF RF AGC ADJUSTMENT
Note:
When power is turned on, tune in to station in the test
mode.
mode.
1.Receive the 40 channel signal(colour bar signal at
87.5% modulated.) at input field strength: 70dB
87.5% modulated.) at input field strength: 70dB
µ
of
antenna terminal.
2.Connect a DC voltmeter to test point shown in table.
3.Look the voltmerter and adjust T1601 so that the
voltage be specified.
2.Connect a DC voltmeter to test point shown in table.
3.Look the voltmerter and adjust T1601 so that the
voltage be specified.
ADJUSTMENT OF VCO CIRCUIT
Measuring
instrument
instrument
Mode
Cassette
Colour TV monitor
Playback still
Self-recorded tape (SP mode)
(See Note below
(See Note below
2
)
Control
Tracking control buttons (+) or (–)
Specification
No vertical jitter of picture
ADJUSTMENT OF PAL SYSTEM FV(False
Vertical Sync) OF STILL PICTURE
Vertical Sync) OF STILL PICTURE
1. Play a cassette which was recorded by the unit in SP
mode.
2. Press the PAUSE/STILL button to freeze the picture.
3. Look at the monitor screen and adjust (+) or (–)
3. Look at the monitor screen and adjust (+) or (–)
TRACKING buttons so that the vertical jitter of the
picture to be minimized.
picture to be minimized.
4. Play and freeze the self-recorded tape in SP mode
and make sure vertical jitter of the picture is not
noticeable.(For the LP mode put adjustment at the
same adjustment way as SP mode.)
noticeable.(For the LP mode put adjustment at the
same adjustment way as SP mode.)
Note:
1
2
Self-recorded tape is a cassette whose program was
recorded by the unit being adjusted.
recorded by the unit being adjusted.
