Marantz 1250 - Page 4

3. TEST EQUIPMENT REQUIRED FOR SERVICING
Table 1 lists the test equipment required for servicing the Model 1250 Stereo Console
Amplifier. The wattmeter, AC voltmeter, and variable autotransformer may be assembled as a
test fixture as shown schematically in Figure 1. The load resistors and AC ammeter may be
assembled into a second test fixture as shown in Figure 2.
Item
Manufacturer and Mode! No.
(or equivalent)
Use
Distortion Analyzer
Hewlett Packard, Model 331A
or 333A
Measures distortion and
voltage of amplifier output.
Audio Oscillator
Weston Model CVO-100P
(NOTE: Less than 0.02 percent
residual distortion is required.)
Sinewave and squarewave
source.
Oscilloscope
Tektronix, Model 503; Data,
Model 555
Waveform analysis and
troubleshooting.
VTVM
RCA Senior Volt-Ohmyst,
Model WV-98C
Voltage and resistance
measurements.
AC Wattmeter
Simpson, Model 390
Monitors primary power
consumption of amplifier.
AC Ammeter
(0 to 10 amps)
Line Voltmeter
(0 to 150V AC)
Variable Autotransformer
(0 to 140V AC, 10 amps)
Commercial Grade
Commercial Grade
Monitors amplifier output
under short circuit condition.
Monitors potential of
primary power to amplifier.
Powerstat, Model 116B
Shorting Plug
Use phono plug with 600 ohms
across center pin and shell.
Adjusts level of primary
power to amplifier:
Shorts amplifier input to
eliminate noise pickup.
Power Supply Bleeder
Resistor (10 ohms at 1W)
Commercial Grade
Discharges power supply
filter capacitors prior to
disassembly or resistance
measurements.
Output Load Resistor
(8Q + 0.5%, 250W)
Commercial Grade
Provides 8-ohm load for
amplifier output termination.
Output Load Resistor
(42 + 0.5%, 250W)
Commercial Grade
Provides 4-ohm load for
amplifier output termination.
Output Load
Capacitor (0.5 mfd)
- Mylar
Provides capacitive load for
instability checks.
AC Power Control Box
Optional item. Fabricate in
accordance with Figure 1.
Monitors and controls
primary power for amplifier.
Amplifier Output
Load Box
Optional Item. Fabricate in
accordance with Figure 2.
Provides various amplifier
joads and can monitor
shorted output.
Table 1. Test Equipment Required for Servicing
OP