Fault Indicator - MC2 Audio E4-75 Owner's Manual

Fault Indicator (Audio Protection – red LED)
If the outputs are shorted or if DC is present, the protection circuit will disengage the outputs and
the A/P LED will illuminate. The amplifier will continue to be monitored and depending on the type
of fault, will either reset after the fault has cleared or require manual resetting by switching off at
the mains switch and then on again after a few seconds. (See also temperature control above.)
Maintenance
CAUTION: These servicing instructions are for use by qualified personnel only. Ensure
that electrical power to the unit is disconnected before carrying out any maintenance.
GAIN/SENSITIVITY SETTINGS
Gain settings are changed internally by simple jumper links. Four rows of pins marked:- GAIN A,
GAIN B, GAIN C and GAIN D - are situated on the input PCB (PCB721). A jumper link sets the gain
and the settings are as follows:
Link 1 & 2
Link 3 & 4
Link 4 & 5
NOTE: Factory setting is normally link 1 & 2 = 32dB gain.
Setting higher gain does not change the maximum available power but changes the level
of signal input to achieve maximum power. In any case, provided that the input signal is
less than 20dBu/7.7V, the built in limiter circuit will prevent distortion within the amplifier.
The gain should be set to match the signal from the source, e.g. mixer, controller,
equaliser etc.
AIR FILTER
The filter behind the air intake apertures on the front of the E4-75 amplifier should be cleaned
or replaced periodically, e.g. 3-6 months. (Filters in amplifiers located in more 'dirty' atmospheres
may require more frequent maintenance.) Access is via the blue front panel. The filter should be
'dry' cleaned, using a vacuum cleaner preferably. Running the unit without a filter is not
recommended unless it is within a 'clean room'. Replacement filter material is available.
No other regular maintenance is required.
If you have any doubt about carrying out this procedure, refer to a service engineer or
contact your dealer.
IF YOUR AMPLIFIER DEVELOPS A FAULT, PLEASE REFER TO YOUR SUPPLIER FOR
SERVICE AND TECHNICAL SUPPORT.
DO NOT ATTEMPT TO REPAIR THE FAULT YOURSELF AS THIS WILL INVALIDATE THE
WARRANTY.
gives 32dB gain
gives 26dB gain
gives approx. 31dB gain = 6dBu/1.5V sensitivity into 4 ohms
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