Marantz PM351 - Idling Adjustment

3.
TEST
EQUIPMENT
REQUIRED
FOR
SERVICING
This
table
lists
the
test
equipment
required
for
servicing
the
Model
pM440
Stereo
Pre
Main
Amplifier.
Item
Distortion Analyzer
Use
Distortion measurements
Audio Oscillator
Sinewave and squarewave signal source
DC VTVM
|_
et i
AC
VTVM
Voltage
measurements
(AC)
LL
:
|
cae
Oscilloscope
Waveform
analysis
and
trouble
shooting
and
ASO
alignment
Circuit
Tester
Trouble
shooting
oa ees
Voltage measurements (DC)
AC Wattmeter
Monitors primary power to amplifier
ate : 2
~Line Voltmeter
Monitors
potential
of
primary
power
to
amplifier
|
| Variable Autotransformer (0 ~.140V AC, 10A)
Adjust level of primery power to amplifier
| . Shorting Plug ;
Shorts amplifier input to eliminate noise pickup
a "ADJUSTMENT RROCERDE aoa
IDLING ADJUSTMENT
ne Set the input. and ‘the. output ofthe unit to OPEN.
ae Corinect a digital voltmeter ' ‘between. TP-1 and: TP-2 of
a channel L, and between TP- 3 and TP-4.of channel. R.
5. FUNCTIONAL EXPLANATION
1. FUNCTION SWITCH
This unit can store more than one week’s schedule in its
memory, thanks to the four source-one monitor high
voltage resistant analogue function switch IC and the
capacitor backup for the memory. When the charge of
the memory backup reaches zero, the tuner will be
initialized. Additionally, the mute signal for the popping
sound caused when the function is switched is output
from DSO2 so that.the input of the main amplifier will
be muted. ,
2 TONE AMPLIFIER
The tone amplifier features a simple design that uses a
single operational amplifier. The level of 100 Hz and
10 kHz can be controlled over a range of +/—10 dB, and
the gain is approximately. 20 dB. The output stage is
connected to the subsonic filter formed by CE21 and
CE22 (0:068 uF). 0.
3.
Turn.on
nthe
power
awitehe
wait
tet
10
seconds,
and
then
"adjust
R735
of
channel
L
and
R736
of
channel
R'so
that
i
‘the
digital
voltmeter.
registers
|
12
mV
(22
mA).
3. POWER AMPLIFIER
The
power
amplifier
uses
the
monolithic
IC
UPC1
270H
which
includes
a
driver
stage
as
the
voltage
amplifier,
and
discrete
power
transistors
for
the
final
stage.
4. PHONO EQUALIZER AMPLIFIER
The
high
gain
phono
amplifier
uses
an-FET
differential
amplifier
together
with
an
operational
amplifier
input
stage.
Low
output
designs
such
as
MC
cartridges
can
be
used
as
well
as
MM,
MI,
or
other
high
output
cartridge
designs.
5. GRAPHIC EQUALIZER
The
first
stage
is
a
buffer
amplifier
which
amplifies
the
input.
by
approximately
6
dB.
QEO1
and.
OE02
(STK
6325A)
of
the
second
stage
are
the
graphic
equalizer
ICs.
They
form
a
five
band
graphic
equalizer
(63
Hz,
25
Hz,
1
kHz,
4
kHz,
16
kHz).