Denon DN-790R - Electrical Section Adjustments

I
DN.TSOF
IOIIISNTUC
THE
ELECTRICAL
SECTIONS
ELECTRICAL
SYSTEM
ADJUSTMENT
o
Gauges
necessary
for adjustment
(1)Lowfrequencyoscillator(2}Variableresistanceattenuator
(3)
Electronic
voltmeter
(4)
Oscilloscope
(5)
Frequency
counter
(6)
Adjustment
driver
(7)
Trap
coil
adiustment
square
regulation
shaft
(8)
Test
tape
(SONY
TY224)
(A-BEX
TCC-1
53,
TCC-130,
TCC-262811628,l.
(DENON
GR-2/60)
(9)
Mirror
cassette
for
playing
A-BEX
TCC-9O2)
.
Adjustment
Notes
(1)
Clean
the
head
surface,
capstan
axis,
pinch
roller'
etc'
with
gauze or
cotton
swabs
soaked
with alcohol
before
adjusting'
l2l
Demagnetize
the
recording
head and
erasure
head
with
the
head
eraser.
(3)
Completely
demagnetize
the adiusting
driver'
(4)Setfunctionswitchesasfollowsunlessspecificallyindicat.
ed.
o
o
o
o
o
o
MONITOR
switch:
TAPE
INPUT
volume:
Maximum
(right
side)
DOLBY
NR
switch:
OFF
BIAS
volume:
Center
(clicking
detent
in center)
TAPE
SPEED
switch:
FIX
AUTO TUNING
switch:
CLEAR
1.
Tape
playing
check
Load
a
mirror
cassette
for
playing
and
examine
the
area
around
the
fixed
guide of
the
recording/playback
head
at
playing
condi-
tion
with
lighting
and
verify
that
the
tape
edge
is
not contacting
the
tape
guide
part. The
tape
playing is the
most
important
ele-
ment
that
determines
the
capacity
of
the entire
cassette
deck'
Make
every
effort
to avoid
moving
the
adjusting
part'
Also'
refer
to
"Adjustment
and
verification
of
mechanical
system"
for ex-
changirE
and
adjusting
the
recording/playback
head'
2.
Azimuth
adiustment
2-1
After
verifying
the
tape
playback, load
the
test
tape
6-BEX
TCC-153).
2-2
Playback
the
test
tape
and
make
any
necessary
adiustment
by
turning
the
azimuth
adjustment
nut so
that
A
and
B in the
Lissajous
wave
figure
are
at
the
maximum
and
minimum
levels
resPectivelY.
3.
Checking
and
Adiusting
the
Tape
Speed
(1)
Connect
the
frequency
counter
to the
LINE
OUT
terminal
and
load
test
tape
(SONY fY-2241'
(21
Playback
a test
tape.
At about
halfway
through
the
tape'
where
the
tape
transport
is
stable,
adjust
the adjustment
points
(RT107)
on
the
P.W.
BOARD
12222848
006)
so
that
the
frequency
counter
will
have
a
reading
within the
range
of 3,000
Hz
+6 Hz'
3.4
s
H
F
I
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I
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l
I
I
F Co unt
er
TY-224
A-BEX TCC-153
Amg
16