NAD 90 - Bias Adjustment Procedure; Alternative Bias Adjustment Method; Adjustment and Check Points

2.
BIAS
ADJUSTMENT
PROCEDURE
The
proper
bias
adjustment
is
most
important
to
assure
correct
performance
of
the
amplifier.
Bias
adjustment
is
necessary
if
any
of
the
transistors
are
replaced
in
the
power
amplifier
circuitry
or
the
amplifier
exhibits
overheating
of
the
output transistors
under
normal
operating
condisions.
INDICATOR
ADJUSTMENT
REMARKS
-----:--.—..-—-—------.
--
.-t----------
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-
Adjust for
0.006 —
0.015 V
across
DC
Voltmeter
VR6O1a,
b
(1
Kohm)
-
R624a,
b
(0.33 ohm)
with
NO
SIGNAL
REMARK:
Bias
can
also
be
adjusted
by
using
a
line
wattmeter.
Adjust
the
VR6O1a
and
VR6O1b
to
the
point
at
which
the
line
wattmeter
shows
very
slight
increase.
3.
ADJUSTMENT
AND
CHECK
POINTS
R624b R624a
V
B
601
b
v
H
60