Marantz 4100 - Phono Amplifier Adjustment; Test Equipment Required for Servicing

trimming resistor R551 until the meter indicator reads +2.
~PHONO AMPLIFIER ADJUSTMENT
Connect
the
audio
oscillator
to
the
PHONO
input,
set
audio
oscillator
frequency
to
1KHz.
Set SELECTOR switch to PHONO.
2.
Connect
the
distortion
analyzer
to
the
TAPE
OUT
terminal
that
is
terminated
by
the
47K
ohm,
set
the
analyzer
on
the
30V
AC
scale
and
connect
the
oscilloscope.
3.
Increase
the
audio
oscillator
output
gradually
until
a
slight
clipping
on
top
of
the
sine-wave
is observed on the oscilloscope.
For the other channel adjust R709.
14.
TEST
EQUIPMENT
REQUIRED
FOR
SERVICING
Table
1
lists
the
test
equipment
required
for
servicing
the
Model
4100
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 1 W)
Output Load Resistor
(82 + 0.5%, 100W)
Output Load Resistor
(4Q + 0.5%, 100W)
Manufacturer and Model No.
(or equivalent)
Apply
the
audio
oscillator
output
until
the
distortion
analyzer
indicates
15V
and
adjust
the
Adjust the trimming resistor R708 for equal clipping level.
Use
Hewlett Packard, Model 331A
or 333A
Weston Mode! 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 ampli
fier output termination.
Provides 4-ohm load for ampli.
fier output termination.
Table 1. Test Equipment Required for Servicing