Mitsubishi DA-C20 User Manual

I
FM
SECTION
l. Front End
Adjustment
1) With the
signals
of
the signal
grenerator
(SG)
connected
to the
FM-ANT terminal,
take
out the
setrs output
from
test
point
r.
P.
(119).
2) With
the SGrs
frequency
set
to
87 1fr12,
turn
the dial
fully
coun te
rc lockwis
e
so
that the
turer
may indicate
the
lowest
frequency.
Adjust
the
local
oscillati-on
coil so
as to
make
the signals
generated
by the SG
maximum.
3) With
the SG's
frequency
set to
109 MHz,
turn
the dial
fu11y
clockwise
so that
the
tuner
indicator
may
show
the
maxi-
mum frequency.
Adjust
the
1ocaI
oscillation
trinuner
Ct91 in
a
manner
to ma]<e
the SGrs
signal
maximrm.
4)
Repeat
Steps
2)
and 3)
several
times
.
5) With the
SGrs frequency
set to
88 MHz,
set
the tuner
to
indicate
88
MHz
with the
dial.
Adjust
coils
L171,
LL72
and. LI73 so
as
to make
the
output
naxi mum.
6)
with the
SG's frequency
set
to
108 MHz,
set the
tuner
to indi-
cate to
108 ItrIz
with
the
dial.
Adjust triruners
TC171, TCI72
and
TC173
so as to make
the output
maximum.
.
Adjustment
of FM-MONO
1)
Set the
SG to 9 8
t"!rtz,
4OO Hz
Lo
MONO
l00A modulation
and
the
out-
put
to B0
dB.
2)
Set the
selector
s\,ritch
of the
set to
the FM
position
and the
mode
to FM-MONO/MUTING
OFF
and
SELECTI
VI TY.WI
DE .
3)
Adjust
the
secondary
side
core
(upper
side) of
T8O2
so
that
the
center meter
may
indlcate
the
center during
detuning
(
approxi-
mately
l-00 MHz).
4)
Tr:ne
the
set to
the
SG's fre-
quenc)l
(98
MHz).
Tuning,
in
this
case.
is
attained
when
the
center
meter
is
a state
in whicf-
it
indicates
the
cen
te.r.
Next,
with
the mode
switch
set
to
FM-AUTO/MIj'I1NG-ON,
adjust
VR751
so
as to
make
the
center
fieter
indicate
the
center.
5) After
connecting
a distortion
meter
to the
output
pin
Lerminal
,
adjust
the primary
side
core
(1ower
side)
of
T8O2
so
as ta
make
the
distortion
factor
minimum.
In
this
case,
if
the
center
meter
does
not
in-
dicate
the
center,
adjust
the
secondary
side
of T802
again
until
it does.
6) Adjust
T803
so
as to
mal<e
the
swing
of the
s19na1
meter
maxi-
mum.
7) Adjust
VR801
so
that
the
siqnal
meter
may
become
4.7
o]j)
the
scaIe.
3. Adjustment
of FM-MPX
1) Set
the SG
to 98 MHz,
L k:H.z
STEREO
to
L+R 902. pilot
to 10%
modulation
arld
the output
to
80
dB.
2)
Set
the
selector
switch
of the
set to
the
FM
position
and mode
to FM-MONO/MUTING-OFF
and to
SELECT]\rITY-WIDE
.
WhiIe
receiving
98
tr&tz
signals
from
the SG,
adjust
the
local
oscillation
trimmer
C191
of the
front
end
in a manner
to make
the
indicator
indicate
9g
MEz
on the
dlal
pIate.
3) Place
the set
to FM-AUTO/MIITING-
ON.
Shift
the
position
of the
indicator
to
the
feft
and right
from
98 MHz
and
confirm
that
LOCK
aid MUTING
operations
are
normal
.
4) After
turning
the
set
again
to
98 ltfr1z,
drop
the SG
output
and
adjust
VRB02
so
that
the wave-
forms
may disappear
(which
im-
plies
that
the
output
is
zero)
at
26 dB
and
re-appear
at 27
dB.
-
11
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Mitsubishi DA-C20 Specifications

General

Brand	Mitsubishi
Model	DA-C20
Category	Amplifier
Language	English