Ecler PAM4100, Руководство по обслуживанию

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51-0054-0100 EP04-99.doc 2 of 4
1KHz 0dB input signal to channel I and, with the volume potentiometer turned up to its maximum,
check with a millivoltmeter that at TP102 a 0dB gain level is obtained. If not, adjust R125. Once
channel I is fixed to 0dB, verify TP102 at channel II and proceed to adjust if gain level is not 0dB.
- Connect a 8
Ω
load impedance to the speakon-type MONO output, and verify the achieved output
power levels:
3500W
167V for PAM6100
2200W 132,6V for PAM4100
Only channel I's input potentiometer should be active. Verify that the amplifier reaches its clipping
state without troubles. Return the unit to its STEREO operating mode.
- Connect a load impedance formed by a 4
Ω
resistor shunted to a 2
µ
2F capacitor, and apply a 1KHz
square waveform input signal. Using an oscilloscope, observe the output signal, and increase the
input signal level until the displayed signal starts clipping. At the flat level areas of the squared
waveform, only two or three ringings should be detected.
- Verify the SUBSONIC FILTER's performance. Check the amplifier’s output level at 40Hz, 30Hz and
20Hz, depending on the selected switch position, is reduced in 3 dB when comparing with the
measured level without subsonic filtering. Leave the selection switch on the 20Hz position.
- Verify the THERMAL protection circuitry. Short the LM35D thermal probe pins 1 and 2, and verify
that the relay releases and closes, while the
THERMAL and PROTEC LEDs indicators light up, as
the output signal is cutted off and the cooling fan increases its speed untill it reaches maximum
airflow.
- Repeat this procedure on the other module.
PROTECTIONS
-
Adjust the signal generator to deliver a 1KHz 0'8Vrms signal, and leave it ON.
- Turn down the power stage volume potentiometer to its minimum.
- Connect a 0'5
Ω
load impedance.
- Connect the oscilloscope test probes parallel to the load impedance. Select a 5V/div vertical scale,
and a 0'2ms/div time base.
- Turn up quickly the volume potentiometer. Depending on wich branch is working, the positive or
negative half of the signal cycle is clipped. Verify that no ringings appear when the protection is
triggered.
- The output signal should be somehow similar to the picture shown in the figure (from 15Vpp to
20Vpp). There are two protection circuitries, one on the positive and another on the negative
branches of the unit. In case one of this protections does not actuate properly, the output signal will
appear completely assymetric. The level of the half-cycle wich is not being protected will not be
limited, thus allowing to find out wich branch is failing. It could also happen that none of the
protections are triggered, this can be detected as the measured signal levels delivered to the load
impedance are not being compressed. In case this happens, inmediately stop the testing procedure.
This may occur when the unit is receiving too low mains voltage (at least 240V, 250V
recommended), or if the signal level is increased too slowly through the potentiometer.
-
After a period between 5 and 10 seconds is elapsed since the protection circuitry has triggered, the
module should switch over into PROTECT operating mode. This is, the relay closes, the PROTECT
indicator LED lights up, output signal is cutted off, and the 10 seconds lasting STANDBY cycle is
started.
-
Wait untill the STANDBY cycle ends, and allow the unit to repeat the process.
-
Turn off the signal generator, output level set to minimum.