Video Head Replacement - Sony AV-3600 Service Manual

4-6.
VIDEO HEAD REPLACEMENT
Video
Head
Replacement
is
required
when
the
heads are
damaged
or
have
open
coils.
In addition,
insufficient
tape penetration, resulting
from head
wear
after
long periods of operation
may
necessitate
replacement.
To remove and
replace the rotary
head
assembly (the
beam on which
the
two video heads
and the slip-rings are
mounted), proceed
as follows.
CAUTION
The
video head assembly and the surrounding
machined parts are very precisely
made. Use utmost
care
when
performing
any
work on
the rotary head-
drum assembly.
Removal
1.
Turn off the power.
Loosen
the screws that hold
the
head-drum
cover.
A
coin will serve as a
screw-
driver for these screws.
Loosen
only half a turn;
do not
try
to
back the screws
all
the
way
out.
Lift
off the
head-drum
cover.
2.
Remove
the
two
Phillips-head screws that
hold
down
the cover
plate.
Loosen
the
brush
pressure
adjusting screws
and remove
the
brush from the
spring as
shown
in Fig. 4-4.
3.
Remove
the
two upper
5
x
20
Hex-Head
Bolts
and washers with
a
4
mm
Allen wrench.
Hold
the
upper
drum
with
one hand
so that
it
does not
fall
as
you
withdraw the
two
screws.
4.
Carefully
lift
the
top of the
drum
assembly and
fold
it
back. Place the
drum
top carefully
on
the reel panel.
See Fig. 4-5.
Loosen these screws
v
x.
slip
ring
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screws
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Fig. 4-4.
Preparation for video
head
replacement
Fig. 4-5.
Video
head
assembly removal
CAUTION
Do
not touch
the
PG
pole
pieces.
Position the rotary head platform by
turning the
aluminum beam on
which
the heads
are
mounted.
Slight
pressure
on
the pole pieces can affect
pole
piece alignment.
5.
Hold
the
Video Head Assembly
to
keep
the plat-
form from
rotating
and loosen the
two
I
4x8
screws that hold the head assembly to
the plat-
form.
Do
not
exert too
much downward
pres-
sure
on
these screws; loosen the locking
com-
pound
with Methyl
Ethyl Ketone.
Remove
the
screws and
the washers.
6.
Using both
hands,
carefully
lift
the
Video Head
Assembly
off the platform.
Replacement
7.
Clean
the
bottom
of the
new
Video
Head
As-
sembly.
Do
not
scratch or
remove the
spacer on
the
bottom
of the
Video Head
Assembly.
8.
Position the platform so that the
30 PG
pole
piece
is
at
the 12 o'clock
position.
9.
Carefully place the
Video Head Assembly
oi
the
platform with the
B
head
(identified
by
the
J"ed
paint) to
your
left
(
9 o'clock position).
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