Adjustment Of The Vcr Electrical; Circuitry - Sharp VT-3428X Service Manual

Notes:
Before the adjustment:
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Electrical adjustments discussed here are often required after replacement of electronic components and
mechanical parts such as video heads.
Check that the mechanism and all electric components are in good working condition prior to the
adjustments, otherwise adjustments can not be completed.
Instruments required:
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Adjustment of the VCR should be done in the TV/VCR combinated style.
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SERVO CIRCUIT
Adjustment of head switching point
Measuring Dual-trace oscilloscope
instrument
Mode
Playback
Cassette Alignment tape (VROCPSV)
Test point
Control
adjustment control
Specification
I. Put the set in the SERVICE mode by turning the
power on with the STAND BY/POWER button
while the CH A button on the front panel is
being pressed down more than 3 seconds.
Play the alignment tape (VROCPSV) and press
the PROG button on the remote control to set
the tracking to center. "TEST" is displayed on
the screen, it means tracking is in center in the
playback mode. (See Note below.)
points TP2208 (Video out) and TP2204.
(Trigger the oscilloscope with the head
switching pulse on TP2204.)
Adjust R7701 so that the leading edge of the
head switching pulse is 6.5H (lines) ahead of
the vertical sync as shown in Figure 2-1.
ADJUSTMENT OF THE
. VCR ELECTRICAL CIRCUITRY
ADJUSTMENT
to the test
@Screwdriver for adjustment
@Alignment tape (VROCPSV)
HEAD .
SWITCHING
P U L S E -
Figure 2-l.
Note:
To make this adjustment, disable the AUTO
TRACKING function.
The AUTO'TRACKING function is disabled in the
following cases.
(In the playback mode only.)
@When the PROG button is pressed after the
tape is played back in the SERVICE mode. (The
display "TEST" appears on the TV screen.
@When the tape is played back, after the cassette
housing control ass'y is removed and the AC
cord is plugged in with making TP8804 and
(Mechanism operating mode, in this case the
SERVICE mode is not needed.
.