Marantz 4070 - Service Adjustments and Equipment; Power Amplifier Adjustment Procedures; Power Supply Voltage Adjustment; Required Servicing Equipment List

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11.
POWER
AMPLIFIER
ADJUSTMENT
Connect
a
VTVM
between
J713(+)
and
J719(—)
and
adjust
the
trimming
resistor
R735
until
the
VTVM
reads
15mV
DC.
And
next,
connect
a
VTVM
between
J715
and
J706
(GROUND)
and
adjust
the
trimming
resistor
R715
until
the
VTVM
reads
OmV
DC.
Do
over
again.
For
the
other
channel,
connect
the
VTVM
between
J714(+)
and
J720(—)
and
adjust
the
R736
for
the
same
reading,
and
connect
the
VTVM
between
J716
and
J706
and
adjust
the
R716
for
the
same
reading. Do over again.
12. POWER SUPPLY ADJUSTMENT
Connect
a
VTVM
between
J819(+)
and
J824(—)
and
adjust
R855
until
the
VTVM
reads
35.0V under no signal condition.
13. TEST EQUIPMENT REQUIRED FOR SERVICING
Table
1
lists
the
test
equipment
required
for
servicing
the
Model
4070
Solid-State
Quadradial
Console Amplifier.
Distortion Analyzer
Audio Oscillator
Oscilloscope
VTVM
AC Wattmeter
AC Ammeter
(0 to 10 amps)
Line Voltmeter
(0 to 150 vac)
Variable Autotransformer
(0 to 140 vac, 10 amps)
Shorting Plug
Power Supply Bleeder
Resistor (10 ohms at 1W)
Output Load Resistor
(82 + 0.5%, 100W)
Output Load Resistor
(42 + 0.5%, 100W)
Manufacturer and Model No.
(or equivalent)
Hewlett Packard, Model 331A
or 333A
Weston Model CVO-100P
(NOTE: Less than 0.02 per-
cent residual distortion is re-
quired.)
Tektronix, Model 503; Data,
Model 555
RCA Senior Volt-Ohmyst,
Model WV-98C
Simpson, Model 390
Commercial Grade
Commercial Grade
Powerstat, Model 116B
Use phono plug with 600
ohms across center pin and
shell.
Commercial Grade
Commercial Grade
Commercial Grade
Measures distortion and vol-
tage of amplifier output.
Sinewave and squarewave sig-
nal source.
Waveform analysis and trou-
ble shooting.
Voltage and resistance mea-
surements.
Monitors primary power con-
sumption of amplifier
Monitors amplifier output un-
der short circuit condition.
Monitors potential of primary
power to amplifier
Adjusts level of primary power
to amplifier
Shorts amplifier input to eli-
minate noise pickup.
Discharges power supply filter
capacitors prior to disassembly
or resistance measurements.
Provides 8-ohm load for ampili-
fier output termination.
Provides 4-ohm load for ampli-
fier output termination.
Table 1. Test Equipment Required for Servicing