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Operating the HCA-1200
Power Switch
Press once to tum the unit on. Press again to tum it off.
Level Controls
Adjust the gain of each channel independently. Many preamps have volume controls which do not track
correclly to preserve channel balance at the lowest end of their rotation. By reducing the settings of the
HCA-1200 level controls you can use the preamp volume control in its optimum range.
Standby LED
This red LED will come on whenever you first tum the unit on. It will light for about four to five seconds
while the circuit is stabilizing before the protection relays click on. It will also light up whenever there is a
short circuit or fault which triggers the protection relays.
Operation LED
This green LED comes on after the protection relay click on. If the amp gets into trouble, the green operation
light will extinguish, advising you no sound can be heard.
Overload LEDs
These LEDs will light up whenever the amplifier is pushed toward its clipping point. They are an indication
that the amplifier is being overdriven and alert you to pending distortion. If you are driving speakers at a
very high level, it is normal for these to flash occasionally on peaks in the program material.
High Temp LEDs
These will alert you to a pending thermal overload of the unit. If the amplifier is overdriven, as it builds up
heat, thermal-tracking sensors will activate protection circuits to keep the unit from frying its power trans-
former or solid state devices. If you find the High Temp LEDs coming on, it is a likely sign that you are
trying to get too much out of the unit for the speakers you are using. It is also a sign that the load impedance
is too low for safe operation.
Protection Circuits
The HCA-1200 has numerous protection circuits. If any are triggered, the red Standby LED will come on.
Afler the fault has been corrected, the unit will automatically reset itself for normal operation. But it is
always a good idea to tum off the power switch while you are trouble-shooting for shorted connections or
faults with source components.
Fuses
The HCA-1200 has several intemal fuses which may blow as a result of an intemal fault condition. This
protects the unit from possible damage to intemal parts. You should not attempt to replace intemal fuses
yourself - there are dangerous high voltages stored in the power supply even after power has been tumed off
or the unit has been unplugged. In any case, never replace any fuse with a larger value. Substitution of a
larger fuse may create serious stress or damage to intemal parts and will void your warranty.
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