Marantz PM500 - Page 4

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1. INTRODUCTION
This service manual was prepared for use by Authorized
Warranty Stations and contains service information for
the Marantz PM500/PM700 Stereo Console Amplifier.
Servicing information and voltage data included in this
manual are intended for use by knowledgeable and expe-
rienced personnel only. All instructions should be read
carefully. No attempt should be made to proceed without
a good understanding of circuitry operation.
The parts list furnishes complete ordering information.
Most replacement parts should be ordered from the
Marantz Company. However, a simple description is
included for parts which can be obtained locally.
2. PRE-AMPLIFIER
The input signal from the PHONO-MM1 or PHONO-MM2
terminal,
selected
with
the
SELECTOR
SWITCH,
is
applied to the PHONO AMP where it is RIAA-equalized
and amplified 36 dB.
(In PM700, the signal from the PHONO-MC terminal is
amplified 56 dB.)
The PHONO AMP output signal is returned to the
SELECTOR switch and is also fed to the RECORDING
SELECTOR (SJ04). The signals from the TUNER and
AUX/TAPE
3
terminals
are
applied
to
the
SELECTOR
SWITCH (SJO1) and to the RECORDING SELECTOR
(SJ04). (PM700 only)
The
signals
from
the
TAPE
1
1N
and
TAPE
2
IN
are
applied
to
the
TAPE
MONITOR
SWITCH
(SJO7)
and
the
RECORDING
SELECTOR
(SJ04).
One
of
five
signals
applied
to
the
RECORDING
SELECTOR
(SJ04)
is
selected
with
the
RECORDING
SELECTOR
and
fed
from
the
TAPE
1
OUT
and
TAPE
2
OUT
terminals.
The signal from the SELECTOR SWITCH (SJO1) is fed
to
the
TAPE
MONITOR
SWITCH
(SJ07),
MONO
SW
(SHO1-2) and then level controlled with the BALANCE
(RGO1) and VOLUME (RGO02) controls.
In the volume control circuit, the signal is controlled
by the loudness control in the LOUDNESS circuit when
the LOUDNESS SWITCH (SG01) is ON. The signal from
the VOLUME (RGO2) control is amplified 19 dB with the
FLAT AMP (QE01-LCH, QE-02-RCH), then fed to the
EQ DEFEAT SWITCH (SH01-1). The amplified signal is
also fed to the ZONE CONTROL (GRAPHIC EQUALIZ-
ER) circuit. The ZONE CONTROL output signal is
applied to the EQ DEFEAT SWITCH (SHO1-1).
The
signal
selected
by
the
EQ
DEFEAT
SWITCH
(SHO11)
is
supplied
to
the
main
amplifier
via
the
FILTER
SWITCH
(SHO1-3
for
PM500,
SHO1-3
and
SHO1-4
for
PM700).
3. TROUBLESHOOTING ANALYSIS
1. Excessive line consumption
a. Check for shorting in QNO1 through to ANO4.
b. Check for any shorted transistors Q717 through to
Q728.
c. Check for open Q715, Q716, 0743, 0744, R737
and R738.
2. No line consumption or zero bias voltage
a. Check line cord and fuse. Check for a shorted
Q715 and Q716. ;
b. Check for open circuits in rectifiersQ717 through
to Q728 and QNO1 through to QN(@4 or for L001.
3. High hum and noise level
a. Check capacitors C421, C422, C803, C804, C811
C812 and Q801 through to Q806.
,
4, POWER AMPLIFIER ADJUSTMENT
ADJUSTING IDLING CURRENT
Connect a DC voltmeter between the emitters of Q725
and Q727. Adjust R741 for 14 mV meter reading.
Perform similar adjustment to R742, Q726 nd Q728.
5. POWER METER ADJUSTMENT
PM500
Connect an 82 load to the left speaker terminals.
Connect VTVM across the 8Q load and an kHz oscillator
to the left AUX/TAPE 3. Adjust the oscilator level for
a 20V VTVM reading. Adjust RX39 (L-Ci} so that the
power meter indicates 50W. Perform the sane adjustment
for the right channel (RX40).
PM700
Connect an 82 load to the left speaker terminals. Connect
VTVM across the 8Q load and an 1kHz osi/# ator to the