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64
TAPE PATH ADJUSTMENT
The tape path mechanism
is precisely
adjusted
at
the factory.
Normally
no readjustment
is required,
but checking and/or
adjustment
is necessary when
parts
of
the tape
path
mechanism
among
those
shown in the figure below (See Fig. 6-4-1.) have been
removed
or replaced
after
a long
period of
use.
This
operation
consists
of
adjusting
the
various
guides so that the tape drawn out from the
SUPPlY
reel runs smoothly
along the DRUM (CYLINDER) lead
surface. A way of grasping
the tape path condition
by electronic
means is monitoring
the video
head
output
envelope
waveform
with
an oscilloscope.
However,
the
fact
that
visual
observation
is
essential
in order
to
know
whether
the
tape
is
running
through
the various
guides
in a smooth
and
natural
way
should
be kept
in mind
when
checking
and adjusting.
Also remember that
the position
of tape guides
is
not
greatly
affected
by the
replacement
of
the
UPPER DRUM (UPPER CYLINDER)
or the
COMPL
DRUM (COMPL
CYLINDER),
provided
that
it
is
correctly
performed,
and
that
only
the
replaced
parts
should
be adjusted
after
replacing
a
tape guide or
COMPL HEAD BRACKET, since the position
of the
other
tape guides
shall
not
change
considerably.
6-4-1.
Preparations
for
Adjustment
(1) ~l;an
the tape transport
surfaces
(See Fig. 6-4-
. .
(2) Connect
the oscilloscope.
Connect
the channel
1 probe to the envelope
waveform
test
point,
and the channel
2 probe to the SW30 (RF SW
P) test point. During adjustment,
apply a trigger
to the low side of the SW30 (RF SW P) in order
to monitor
the waveform
output
from
channel
1 of the video
head.
Note : Since oscilloscope
connection
points
differ
according
to the model, refer to the
"Test
Point for Tape Path Adjustment"
allocation
figure
in
the
electric
circuit
adjustment
section
of the service
manual
book.
(3) Use a dentist's
mirror for visual observation
of
tape path condition.
(4) Use a nut
box (VHJ-0048)
for
adjustment
of
the fixed
guides.
(5) Use
an
eccentric
driver
( VHJ -0003
) for
adjustment
of the guide
rollers.
(6)
When
adjusting
height of the fixed guide, guide
rollers or COMPL head bracket, turn
the special
nut or the upper flange
clockwise
to push the
tape downward,
and counterclockwise
to make
the tape rise UP.
(7) DO not use the damaged cassette tapes for tape
path adjustment.
.
Entrance
guide roller
Exit guida roller
Special Nut for height
Impedance
HE
Pinch
Entrance
Fixed gui
Tensio
lever
Screw
for
azimuth
Fixde guide (T)
Capstan ~le
adjustment
roller
Fig. 6-4-1.
Preparation
for
Adjustment
–72–
.-
.
. . . ... ..- -
.'
v.'",
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