II.
FINAL TESTING
(This setup should have signal input to Amplifier through female (XLR)
(The limiter link should be out of circuit initially.)
1.
Connect the Amplifier to the setup, set voltage selector switch to 240V
2.
Switch ON the set to 240VAC.
3.
Slowly increase the input signal (of 1kHz) keep watching the 24dB LED, it should
glow at approx 9V output. Increase the input signal to get 70VAC output.
4.
Check Dc voltage of all emitter resistors, Minimum value should be within 30% of
the maximum value.
5.
Slowly increase the input signal, keep watching the 0db LED, it should glow at 100V
±
5V output voltage.
6.
Set 100V 1kHz as 0db reference. Change frequency to 10kHz check dB level drop. It
should be 2.5dB
±
0.5dB.
7.
Change the frequency to 1kHz, reduce signal level to get 10VAC output. Half the
output load.
8.
Overload setting
: - Check the DC voltage at the emitter resistors having the
maximum voltage value. Increase input signal to get 820mV for DCM 120, 425mV
(for DCM250 & DCM 500). Turn preset (P2) anticlockwise such that it just mutes
the output signal and signal returns back slowly after 2 seconds.
9.
Reduce the signal & re check whether the signal mutes at the corresponding above
stated voltages.
10.
Again make the output load to original full value. Turn volume preset fully
anticlockwise, set input signal strength to 1V, set volume preset clockwise to get
100V output.
11.
Set input signal strength to get output 110V VAC. Insert limiter link, the signal
should reduce to 100V
±
5V.
12.
Remove the input signal and check noise. It should measure less than 25mV.
III.
THERMAL & SOAK TEST
1.
Connect the Amplifier to the setup : Output load = 4
Ω
Output Voltage: (DCM 120):
14V. (DCM 250):20V. (DCM 500): 40V
2.
Set the Amplifier thermal cut off temperature at around 105
°
C with the help of preset
P4.
3.
Leave the unit “ON” (with lid fixed, if possible) for 24 hours.
IV.
Sound Test/Listening test.
1.
Switch On the set. Check for any switch on thump.
2.
Connect CD player to the input, listen for irregularities if any.
3.
Switch off the set check for switch off noises.
