Advertisement
Power
Amplifier
Section
1.
Do not
connect
load
to
speaker
terminals.
Set
VOLUME control at minimum.
2.
Set power boosting switch
to
4cH
position.
Then energize
unit.
3.
For the first
approximately
six
seconds, the
relay remains open, keeping the
unit
muted.
confirm that all
voltages are as
indicated
in
the
circuit
diagram on page 88.
4.
If
voltages
are greatly different from
rated
values,
shut
off
power
immediately.
check
suspicious areas, especially
power supply circuit
assembly.
5.
If
the relay
opens
immediately after the power
amplifier
has been come
into
operation,
a
defect
in
the
output
transistors
can be
suspected.
Check
the output
stage.
Bottom View
6.
After
approx. 10^'20 minutes
of
warming-up
time, adjust vR101
so
that the
voltage
across
terminals
58
and G3
of
the
power
amplifier
assembly becomes
20mV.
7.
In
the
same
way, adjust the following
variable
resistors
to
obtain 20mV
voltage readings
across
the following terminals:
Terminals
49
- 55
VRI02
Terminals
40
-
46
Terminals
32
-
37
VR103
VRLO4
VR104
VR103
VR 102
8.
Next,
connect voltmeter between terminal
60
and
ground. Adjust vR1
to
obtain
0v
reading.
9.
In
the
same
way, adjust the following vRs to
obtain zero
readings
at the following points:
Terminal
52
and
ground
VR2
Terminal
43 and
ground
VRg
Terminal
35 and
ground
VR4
Top View
VR4
VR3
VR2
46(+)
49 (+)
63(+)
VR
1O
VR1
Advertisement
