Instruction manual

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Power amplifier switch current is sensed by current transformers and used on the control board to
provide peak and average current limiting. Thermal switches mounted to the amplifier heat sink
and one of the snubber resistors are used to sense overtemperature conditions. If either of the
switches is activated, the amplifier output is disabled until the overheated component cools down.
A power supply comparator on the control board disables the amplifier output if the supply is below
a safe level.
5.15. CURRENT TRANSFORMER BOARD
The current transformer board, A7, holds three current transformers, one per power amplifier, to
sense the output current of each amplifier. The current transformers are terminated with variable
resistors used for current sense calibration. Also on the current transformer board are monitor
connections to the output terminal block, TB3. These monitor signals are sent to the front panel
voltmeter on the current limit assembly.