Sharp VC-MH80 Service Manual page 23

ADJUSTMENT OF TAPE DRIVE TRAIN
1.
Remove the cassette housing control assembly.
2. Make a short-circuit between TP5001 and
TP5002, both located on the timer PWB. Now
turn on the power.
3. Check and adjust the position of the tension
pole. (See page 18.)
4.
Check and adjust the video search rewind back
tension. (See page 17.)
5.
Set the tilt angle of the A/C head. (See page 21.)
6. Rough adjustment of tape drive train.
a) Connect the oscilloscope to the test point for
the synchronism of the oscilloscope to EXT.
The PI3 CHROMA signal is to be triggered by
the head switching pulse (TP2202).
b) Loosen the setscrew at the lower part of the
guide roller, and adjust it with an adjusting
screw driver (JIGDRIVERH-4) so that the guide
roller turns smoothly. (Do not overloosen the
setscrew, which causes insecurity of the guide
roller.) (See Figure 4-33.)
c) Set the alignment tape (monoscope pattern)
on the reel disk, and place the unit in the play-
back mode.
(Place a 500 g weight on the cassette tape to
prevent floating of the cassette tape.)
Hexagon
d) In the X value adjustment mode (see the Elec-
trical Adjustment), change the envelope
waveform from MAX to MIN, and MIN to MAX
by pushing the (+) or (-) tracking button, and
check a flat response is obtained on the wave-
form.
e) If a flat response cannot be obtained, roughly
adjust the guide rollers on the supply side and
take-up side using an adjusting screw driver
until a flat response can be obtained.
screwdriver to prevent the tape from wrin-
kling at the upper and lower flanges of the
fixed guide.
1) Wrinkles at the upper flange : Turn the
above adjusting screw clockwise, as shown
in Figure 4-35 (a).
2) Wrinkles at the lower flange : Turn the
above adjusting screw counterclockwise, as
shown in Figure 4-35 (b).
Wrinkles at upper flange
Wrinkles at lower flange
Notes:
1. Place the tracking control in the center position,
and adjust the X-position adjusting nut so that
the PB CHROMA envelop becomes maximum for
easier rough adjustment of the tape drive train.
2. In the rough adjustment, pay particular atten-
tion to the outlet side.
Loosen the setscrew
Clockwise
Counterclockwise