Sharp VT-3428X, Service Manual, Page: 33 / 136

Push the or tracking button to check
that
a
flat response is obtained on the
envelope waveform.
the guide roller by tightening the
guide roller setscrew in the unloading mode.
Play back the tape drive train alignment tape
to check that the envelope waveform does
not change.
Adjustment of A/C head X-position.
a) In the X value adjustment mode (see the
Electrical Adjustment), make a short circuit
between
and both located at
the on your side on the VCR with a
ohm resistor to center the tracking.
Rotate the X-position adjusting nut with an
adjusting box driver, and adjust the A/C head
position for maximum head switching pulse
low side envelope.
Adjust the playback switching point.
Check the flatness of the envelope waveform
and sound by playing back a recorded tape.
X-position adjusting nut
Main chassis
Figure
REPLACEMENT OF THE CAPSTAN
(DIRECT DRIVE) MOTOR
Remove the cassette housing control assembly.
R e m o v a l ( F o l l o w t h e o r d e r o f i n d i c a t e d
numbers.)
Disconnect from the board-to-board connector
on the VCR
Remove the reel belt
Remove the screws
Figure Figure
l Reassembly
Mount the capstan motor on the mechanism
chassis making sure not to allow the capstan
shaft to hit the mechanism chassis, and attach it
with the three screws.
Attach the reel belt. Reconnect to the board-to
board connector on the VCR
Notes :
After installing the capstan motor, be sure
to rotate the capstan motor and check the
movement.
Check the servo circuit.
REPLACEMENT OF MOTOR
Put the unit in the cassette eject position.
Unplug the power cord.
l Removal (Reverse the order in reassembly.)
Disconnect the cable
Unscrew the assembly fixing screws
Take out the assembly
Unscrew the rotor assembly fixing screws
Take out the rotor assembly
Notes:
In removing the assembly, part of the
drum earth spring pops out of the
collar.
Be careful not to lose it.
Secure the rotor assembly so that the
installation positioning holes in the rotor
assembly and upper drum assembly match.
(Match the upper drum’s notch with the rotor’s
hole.)
Be careful not to damage the upper drum or the
video head.
Be sure that the hall device and the
assembly are not damaged by the rotor assembly
or other parts.
After installation, adjust the playback switching
point.
2
motor