Sharp VC-S2000HM, Service Manual

Page: 29 / 123

29
VC-S2000HM
SERVO CIRCUIT ADJUSTMENT
ADJUSTMENT OF HEAD SWITCHING POINT
Measuring
instrument
Mode
Cassette
Dual-trace oscilloscope
Colour TV monitor
Playback (TBC/DNR OFF)
Alignment tape (VROCPSV)
Test point Pin(2) of P201 (H.SW.P.) to CH-1,
VIDEO OUT jack to CH-2
(CH-1 trigger slope switch at (+),
Internal trigger at CH-1 side.)
Specification 7.5
±
0.5H (lines)
1. Remove the front panel and play the alignment tape.
(VROCPSV)
2. Press the PLAY button.
(Playback picture on the monitor screen.)
3. Make for a moment short-circuit P802, located at the
front side on the main PWB.
Be sure that all the fluorescent display tubes light up
into the TEST mode.(See Note below)
Press the PLAY button again.
Be sure the "PLAY" appears in the fluorescent display
tubes. It takes a few seconds for the auto PG adjust-
ment operating.
Note:
When the manual PG adjustment, obseve the wave-
form with an oscilloscope and make adjustment FF or
REW button so that the specification.
4. Press the STOP button in the return to normal mode.
5. Make this checking of waveform on the oscilloscope
screen be as shown in Figure 5-2. just after the head
switching point have been adjusted.
Note:
1
Set-up of TEST mode.
When the adjustment of HEAD SWITCHING POINT,
AUTO TRACKING function is invalid.
2
When the cassette housing control ass’y is removed,
set-up of mechanism operating mode.
1) Replug the AC power cord it a few minutes later.
2) Make a short-circuit P801 located at the front side on
the main PWB, and press both tracking control button
at the same time to set the tracking in center.
3) AC power cord is plugged in.
4) You can mechanism operatig mode, Replug the AC
power cord a few minutes later.
Measuring
instrument
Mode
Cassette
Colour TV monitor
Playback
Self-recorded tape
(SP/LP mode)(See Note below)
Control Tracking control buttons (+) or (–)
Specification Minimized noise on
monitor screen
ADJUSTMENT OF PAL SYSTEM SP/LP/EP
SLOW TRACKING PRESET
1. Have the unit to receive a good TV broadcast or feed a
video signal to the VIDEO IN jack. (See note
2
below)
2. Set the tape speed in SP mode by using the remote
control and record the signal on tape.
3. Rewind and play the tape where signal was recorded in
above step.
4. Press the SLOW button on the remote control, and
playback the recorded portion in the slow mode.
5. Make for a moment short-ciucuit P802, located at the
front side on the main PWB.
Be sure that all the fluorescent display tubes light up
into the TEST mode.
6. Look at the monitor screen and adjust the (+) or (–)
TRACKING buttons so that the there is noise disap-
pears from the screen.
7. Press the STOP button to return to normal mode.
8. Play the tape a few seconds then press the SLOW
button again and make sure there is no noise in the
screen.(For the LP/EP mode put adjustment at the
same adjustmet way as SP mode.)
Notes:
1
Self-recorded tape means a cassette whose program
was recorded by the unit being adjusted.
2
The TV program will not be recorded if RCA or 21pin
plugs are pluged in to the AUDIO/VIDEO input termi-
nals.
3
There is a noise on STILL PICTURE of EP mode.
Please adjust a noise minimized on monitor screen.
7.5 – 0.5H (lines)
CH-1: 1V/div 50 s/div
CH-2: 2V/div 50 s/div
V-sync.
CH-1
HEAD
SWITCHING
PULSE
CH-2
VIDEO OUT
Figure 5-2.