Marantz PM350 - Performance Testing and Verification; Required Test Equipment for PM350 Servicing; Performance Verification Preliminary Procedures

7. TEST EQUIPMENT REQUIRED FOR SERVICING
Table 1 lists the test equipment required for servicing the
Model PM350 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.
8. PERFORMANCE VERIFICATION 2.
TEST PROCEDURE
A. TEST EQUIPMENT
Refer to Table 1 for required test equipment.
B. PRELIMINARY PROCEDURES
Make the test setup shown in Figure 1 with the
instrument controls set in the following positions:
| tem | Manufacturer and Model No.
Distortion Analyzer
Audio Oscillator Sound Technology Model 17008
AC Voltmeter -
Tektronix Model T932
Philips Model 3232
Oscilloscope
Line Switch OFF
Variable-line switch Variable
Wattmeter Switch ON
Variable Autotransformer 0 V (fully CCW)
Load 8 ohms (0.5 mfd—OFF)
Audio Generator 1 kHz
Output 5 V range
Gain Minimum
AC Voltmeter 30 V range
Make sure that connections between the resistive
load and the system terminals of the Model PM350
have negligible resistance when compared with the
resistance of the load itself. Appreciable resistance
in wiring adds to the total joad, resulting in inaccu-
rate measurements of output power.
Connect amplifier output to load and connect AC
cord to line power. Connect shorting plugs to the
Phono input jacks of the Model PM350.
Table 1. Test Equipment Required for Servicing
Use
Distortion Measurements
Sinewave and squarewave signal source
voltage measurements (AC)
Waveform analysis and trouble shooting and
ASO alignment
Circuit Tester
I Trouble shooting
DC Voltmeter
Model 313, Triplet Mode! 801
AC Wattmeter Simpson Model 1379
AC Ammeter Commercial Grade (1 ~ 10 A)
Line Voltmeter Simpson Model 1359
Superior Electronic Co.,
Powerstet Model 116B-10A
Use phono plug with 600 ohm
Variable Autotransformer
Shorting Piug
across center pin and shell
Output Load
: Commercial Grade
(8 ohms, +0.5% 100 W)
Fluke Model 8000 “Digital” Simpson |
Voltage measurements (DC)
Monitors primary power to amplifier
Monitors amplifier output under short circuit
condition
Monitors potential of primary power to
amplifier
Adjusts level of primary power to amplifer
Shorts amplifier input to eliminate noise
pickup
Provides 8-ohm load for amplifier output
termination
Output Load . Provides 4-ohm load for amplifier output
Commercial Grade wie
(4 ohms, 0.5% 100 W) _ termination
Output Load Capacitor
Mylar
(0.5 mfd)
Optional Item. Fabricate in
AC Power Control Box . .
accordance with Figure 1
a Optional! Item. Fabricate in
Amplifier Output Load Box . ;
accordance with Figure 2
Provides capacitive load for instability chcks
Monitors and controls primary power for
amplifier
- Provides various amplifier loads and can
monitor shorted output