Ecler MPA4-400, Service Manual, Page: 63 / 72

51-0098-0100 EP14-02 Anglès.doc 3 of 4
- Channel 1’s Signal Present indicating LED lights up. Turn up channel one’s potentiometer.
Verify its sweep. Vo=41V
rms
. Check that the output corresponds to the used channel.
- Channel 2’s Signal Present indicating LED lights up. Turn up channel two’s
potentiometer. Verify its sweep. Vo=41V
rms
. Check that the output corresponds to the
used channel.
- Both outputs are in phase.
- On the channel’s ST/B IN1/B IN1+IN2 switch, select IN1+IN2. By now both outputs
should be push-pull configured. The S.P.2 indicating LED turns off. Verify that now only
channel one’s input potentiometer is active, and leave it up to its maximum position.
- Change the millivoltmeter/oscilloscope test probes from the actual outputs to outputs
3-4.
- Verify that channel 3’s Signal Present indicating LED is lit. Turn up channel 3’s input
potentiometer. Verify it’s sweep. Vo=41V
rms
. Check that the output corresponds to the
used channel.
- Verify that channel 4’s signal present indicating LED is lit. Turn up channel 4’s input
potentiometer. Verify it’s sweep. Vo=41V
rms
. Check that the output corresponds to the
used channel.
- Both outputs are in phase.
- On the unit’s ST/B IN1/B IN3+IN4 switch, select IN3+IN4. By now both outputs should
be push-pull configured. The S.P.4 indicating LED turns off. Verify that now only channel
three’s input potentiometer is active, and leave it up to its maximum position.
- Verify that all CLIP-indicating LED’s are lit. If necessary, add 1 or 2 dB’s to the input
signal level.
- On the IN1/IN1+IN2 switch, select IN1+IN2. Check that the output level has dropped
6dB.
- Leave the switch again to IN1.
BURNING TEST.
- Leave the unit loaded and connected to its nominal mains voltage, while applying input
signal, and keep it working at 3dB under its maximum output level during 24 hours.
SAFETY VERIFICATION TESTS.
Preliminary:
- Unplug the unit to be tested from the mains outlet.
- Short all ground terminals from signal inputs, outputs and other external connectors,
except the mains plug’s ground.
- Turn ON the unit’s main power switch.
Ground continuity test:
- Connect the tester’s probes between the mains ground contact and the unit’s backside
main ground test point. When applying a 10A current, verify that the ground impedance is
lower than 0’1
Ω
.