AUSTRALIAN MONITOR DCM Series, Service Manual

TESTING PROCEDURE OF DCM 120/DCM 250/DCM 500 

I.

PRE-TESTING (of complete sets). 

•

Check  

1.1

All screw for tightness (Bridge rectifier and transistor bolts) 

1.2

Earth Connection for good contact (solder and crimpling) 

1.3

This setup has signal input to the Amplifier through male (XLR) 

1.4

Check with Multimeter that there is a DC resistance of about 250 

Ω

 between 

Pin2 & Pin3 of each of XLR’s. Also between (Pin 1 & Pin 3) and (Pin1 & Pin2). 
There should be very high resistance. (IE: no reading). 

2.

Electrical Check 

2.1 Fuse Check: 
 

DCM 120 

DCM 250 

  DCM 500 

Mains fuse: 

    4AT   

  6.3 AT                  10 AT 

DC fuse:                        10AT (x1)           

10AT (x2)             35AT (x2) 

2.2 Connect the Amplifier to the setup (Variac voltage = 0V) set all presets on front 

board (only) fully clockwise, voltage selector switch to 230V 

2.3 Slowly increase the input voltage to 230V, keep watching the input current 

should not exceed 0.1A for DCM-120, 0.1A for DCM-250, 0.1A for DCM 500. 

2.4 Check and reset if necessary all emitter resistor voltages with the help of preset.  
      (Each emitter resistor voltage should be between 0.5 mV to 0.8 mV )

2.5 Check DC voltage Main rail = 33V 

7815 input = 30V 
7815 output = 15.5V 

2.6 Give input signal of 500 mV to get outputs as follows (@ 4

Ω

 output load)/ 22V 

for DCM 120, 32VAC for DCM250,   44.7VAC for DCM 500. Check 100V O/p 
at 100vV line, Remove the input signal