Advertisement
®@ ADJUSTMENT
= TESTING
PROCEDURES
Perform the test according to the following procedures.
1.
Using
a tester,
measure
the voltage between
the
chassis and collector of the power transistor O2 or O85.
If a tester indicates approximately 68V, it is normal.
2.
Also measure the voltage between the chassis and
collector
of the power transistor O3 or O4.
If a tester
indicates approximately 34V, it is normal.
RIGHT
channel
= IDLING CURRENT
1.
Connect
the dummy
load
(82, 80 watts)
to the
output terminal.
2.
Connect the audio generator to the main unit.
Oscilloscope
and AC
VTVM
are connected
across the
dummy.
.3.
Before checking the idling current, turn on power
switch
in a few
minutes,
adjust the variable
resistor
(VRe1, 2) so that tester (or DC VTVM) coupling to the
collector
of transistors
indicates
30mA.
And _ also
check
the waveform
to be correct feeding the signal
(1kHz) to the set.
LEFT
channel
= ON METER
SETTING
_ As supply the signal (1kHz, 100mV) to the MAIN-IN jack,
setting POWER
LIMITER
at FULL,
PRE-MAIN
SEPA-
RATE
SW
at SEPARATE,
right meter
indicates around
the OVU.
And then adjust the PC trimmer potentiometer
VR5 (3k) so that left meter indicates the OVU as well as
right.
= ON MIC JACK
As
plug
the
MIC
jack
in MIC-L
speakers
work
as
monophonic.
And
then the MIC jack in MIC-R only
right speaker does.
Next plug MIC jacks in MIC-R and
MIC-L each speakers work as stereophonic.
C171
(C271)
R173
VRS = 3kQ
(R273)
(R182 = 1.8kQ)
Advertisement
