Sharp VT-3448X, Service Manual

Page: 39 / 144

Push the or tracking button to check that a flat
response is obtained on the envelope waveform.
Secure 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 right on your side on the
main and plug in the AC cord, to center the
tracking.
Move the A/C head arm with an adjusting gear driver,
and adjust the A/C head position for maximum head
switching pulse low side envelope.
Finally tighten the screws
and (First tighten the
screw and next the screw (Figure
(Reference: Final tightening torque: as prefer-
able.)
Adjust the playback head switching point.
Check the flatness of the envelope waveform and sound
Figure
by playing back a recorded tape.
REPLACEMENT OF THE CAPSTAN
(DIRECT DRIVE) MOTOR
l
Remove the cassette housing control assembly.
l Removal (Follow the order of indicated numbers.)
Disconnect from the board-to-board connector on the
sensor
Remove the drive belt
Remove the screws
Capstan
motor
Capstan
motor
1
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 con-
nector on the sensor
Notes:
After installing the capstan motor, be sure to rotate the
capstan motor and the movement.
Check the servo circuit.
REPLACEMENT OF DRUM MOTOR
Put the unit in the cassette eject position.
Unplug the AC 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 head switching point.
1
Figure