Marantz SM500DC - Servicing Procedures and Test Equipment; Required Test Equipment; Idling Current Alignment Procedure; Power Meter Alignment Procedure

4. TEST EQUIPMENT REQUIRED FOR SERVICING
This table lists the test equipment required for servicing for the Model SM500DC Stereo Power Amplifier.
Item
Manufacturer and Model No.
Distortion Analyzer
Audio Oscillator
AC Voltmeter
Sound Technology Model 1700B
Use
Distortion Measurements
Sinewave and squarewave signal source
voltage measurements (AC)
; Tektronix Model T932
Oscilloscope oa
Philips Model 3232
Circuit Tester
Waveform analysis and trouble shooting and
ASO alignment
Trouble shooting
DC Voltmeter
Fluke Model 8000 “‘Digital’’ Simpson
Model 313, Triplet Model 801
Voltage measurements (DC)
AC Wattmeter Simpson Modei 1379 Monitors primary power to amplifier
AC Ammeter
Commercial! Grade (1 ~ 10 A)
Monitors amplifier output under short circuit
condition
Line Voltmeter Simpson Model 1359
Monitors potential of primary power to
amplifier ,
Variable Autotransformer
Superior Electronic Co.,
Powerstet Model 116B-10A
Shorting Plug
Output Load
(8 ohms, +0.5% 100 W)
Output Load
(4 ohms, +0.5% 100 W)
Use phono plug with 600 ohm
across center pin and shell
Commercial Grade
Commercial Grade
Adjusts level of primary power to amplifier
Shorts amplifier input to eliminate noise
pickup
Provides 8-ohm load for amplifier output
termination
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
CL
Optional Item. Fabricate in
accordance with Figure 2
Provides various amplifier loads and can
monitor shorted output
5. ALIGNMENT PROCEDURES
5.1 Idling Current Alignment Procedure
Where to be adjusted: R733 and R734
Adjusted value: 20 mV (20 mA ea.)
’ Procedure
1 With the input of the set placed in Open, set the
power switch to ON.
2 Adjust semi-fixed resistance, R733 and. R734, so
that the voltage of both the ends of R741 and R742
may become 20 mV after 10 seconds.
5.2 Power Meter Alignment Procedure
Where to be adjusted
Lchannelee-< Gees atk eee Ga, ae dee eek RX74
R: channelnns sh. SSNS ees tele eees RX08
Procedure
1 Connect the load resistance 892 to the speaker ter-
minal of the set.
2 Connect the 1 KHz from SG to input.
3 Set the power switch of the set to ON, increase the
SG output, and adjust the speaker output to be-
come 50W — 822 (20V).
4 Adjust RX07 and RX08 so that the meter may indi-
cate 50W (82).