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5. ADJUSTMENT
O
DC
BALANCE
Adjust DC
balance
in
following
steps:
(a)
Connect
the
audio
generator
through
the
attenuator
to
MAIN
IN
terminal.
(b)
Connect
the
oscilloscope
and
V.T.V.M.
to
SPEAKER
OUTPUT terminal
as
shown
in
Fig.
1.
(c)
Connect
the load
resistor
(8
Q
BOW)
in
parallel
to
SPEAKER OUTPUT terminal
as
shown
in
Fig.
1.
(d)
Turn
the
PRE-MAIN
switch
on the
rear
panel
to
SEPARATE position.
(e)
Apply the
1
kHz input
signal
to
the
MAIN
IN
terminals
until
the
waveform
on
the
scope
is just
clipped.
(f
) Adjust the
semi-fixed
potentiometers
(VR1, VR2) in
the
printed
circuit
board
and
positive/negative
half
cycles
of
the
output
waveform
on
the
scope
is
just
clipped
at
the
same
time.
O IDLE
CURRENT
Adjust the idle current
in
following
steps:
(a)
Disconnect
the input
signal.
(b)
Take 15
minutes
for
warming
uP.
(c)
Connect the
DC
V.T.V.M.
to
the terminal
13
of
the main amplifier's printed
circuit
board,
the
positive
lead
of the
DC
V.T.V.M.
is
connected
to
the
terminal
13
and
negative
is
connected
to
ground
terminal
as
shown
in
Fig.2.
Adjust the
semi-fixed
potentiometer
(VRB) in
the
printed circuit
to
get 10
mV
reading
on the
DC
V.T.V.M.
Likewise,
adjust
the VR4
by
connecting
the
positive lead
of
DC
V.T.V.M.
to
the terminal
14.
sA-600
t-_l
lr^
n+l;{
t-"1
(d)
(e)
Fis.
1
Fis.
2
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