Denon DN-790R - Mechanism Adjustment and Checking

DN-79t]F1
ADJUSTING
AND
CHECKING
THE
MECHANISM
SECTION
1.
Exchanging
pinch
roller
Before
exchanging
the
pinch
roller'
clean
the'tape
contact
sur-
faces of
the
pinch
roller and
of
the
capstan
shaft.
Defects
on
tape
playing
are
primarily
caused
by
a dirty
pinch
roller or
capstan
shaft.
The
right
pinch
roller arm
(?)
can
be
detached
by
removing
the
washer
@
.
rne
left
pinch
roller arm
(!!)
can be
taken
out
by
removin!
The spring
@
ano
the
nylon
nut
@
'
After
exchanging
the
pinch
roller,
run a
tape
without a
C-90
butt
and
verify
that
no t4pe
curling
occurs
at
the
tape
guide and
the
tape
guide
part
on
the
record/playback
head.
Normal
condition
Def ective
running
condition
Curl
2.
Verifying
pinch
roller
crimping
ln the
playback
condition,
hook
a stick
type
spring
balance
to the
bracket
on
the central
axis.of
the
pinch roller'
After
pulling
the
pinch
roller away
from
the
capstan
shaft,
let the
pinch
roller con-
tact
the capstan
shaft
as
it
is
and
verify
that the
readings
on
the
stick
type
spring
balance
are
250
to 350
g
on
the
right side
and
70
to
150
g
on
the
left when
the
pinch
roller
starts
turning
lf the
readings
exceed
the standard
values,
replace
spring
@
or
@
Capstan
shaft
Right
side
25O-35O
g
Left side
70-
150
g
3.
Exchanging
recording/playback
tread
@
Detach
the
front
Panel
first.
3-1
Dismounting
recording/playback
head
t
(1)
Detach
the
recording/playback
head
locking
screw
(72!
(21
Remove
soldering
on
the
head
wire and
separate
the
me-
chanical
unit
to dismount
the
recording/playback
head'
3-2
Recording/playback
head
installation
Assembly
is
the
reverse
of
the
installation
procedure de-
scribed
in section
3-1
The soldering
for the
head
wire
is
performed
as
shown
in Figure
3-1.
ozimuth
odjustment
til.t
odjustment
screw
Recording/playback
head
Adiustment
Height
adjustment
(adjust
with
head ad!ustment
jig
THG-801
)
Set
THG-801
(jig
board) on
the
mechanical
unit and
perform
the adjustment
by
turning
the
special
height adjustment
."r"*
@
so
the 3.8
mm
part
on
THG-801
(jig
shaft)
can
move
without
touching
the
tape
guide
on
the
recording/
playbackhead
@.
Turn
the azimuth
adjusting
,"r"*
@
so that
the
record-
ing/playback
head does
not
tilt
while adjusting
the
height,
and
make a
rough
visual
adjustment.
4-2
(1)
tzl
4-3
)
Ji9
(
4.
4-1
(1)
l2t
I
Pinch roller
L
14
Pinch
roller
l
l
I