Internal Configuration Switches; Faults/Fuses - MC2 Audio MC450 Operating Instructions Manual

2 ohm & Bridged LEDs
These indicate the position of the switches on the rear panel. The 2 ohm LED will also illuminate if the
controller senses a low impedance load (excessive temperature rise).

INTERNAL CONFIGURATION SWITCHES

As these can only be accessed by removing the top panel this should only be carried out by qualified
personnel.
The control PCB is located on the side of the unit behind the front panel. The switches are an 8 switch
DIL package at the rear of the PCB. For full description of the switches consult the Service manual.
The standard configuration is for all switches to be ON, except Sw2 and Sw6, which are normally OFF.
Sw 1 Temp LED operation. ON = Standard position, OFF = alternative position. (See
temperature control section above.)
Sw 2 (Normally OFF) This selects the auto reconnect mode. If switched OFF when a fault has
been detected, the amplifier will not reconnect the outputs even when the fault is cleared.
This is a safety requirement in certain applications.
Sw 3 (Normally ON) When OFF the LED columns will always show the signal level and will
not change to show the level control position when the level controls are adjusted.
Sw 4 & 5 These select the threshold level as follows:-
Sw 6 & Sw 7 operate together, they determine the operating mode and release time of the limiter as
follows:-
Sw6
OFF
OFF
ON
ON
Sw 8 (Normally ON) This sets the attack time of the limiter. ON = Fast

FAULTS/FUSES

There are internal secondary (low voltage) fuses on all the internal supply rails. If one of them blows the
amplifier will indicate a fault on both channels and the unit will power down. If the controller (5 volt)
supply fails all LEDs will go out and the unit will shut down.
The unit must be disconnected from the mains supply, and the fuses replaced before switching the unit
back on. They should be replaced with the same type fuses only.
THIS SHOULD BE CARRIED OUT BY QUALIFIED PERSONS ONLY.
Sw4 Sw5
ON ON Just below clipping point.
ON OFF 1dB below clipping point.
OFF ON 2dB below clipping point.
OFF OFF 3dB below clipping point.
Sw7
OFF Release time = slow
ON Release time = fast
OFF Automatic Gain Control mode. (Once the level has
been reduced it will emain at that level until changed
manually).
ON Limiter disabled.
8
Function
OFF = Slow