Hafler p4000 User Guide

– 16 –

The Short detector monitors the Drive Signal and Output Signal levels and shuts down that channel when a shorted
output condition is detected. Recovering for the Short protection requires turning the amplifier off to reset it.

The comparator U4B monitors the Drive Signal and goes low when the drive level is sufficient to clip the output stage.
The drive signal clip status is connected to the input of U4A on pin 7, the Output Signal is connected to the input of U4A
on pin 6. The output of U4A goes low when pin 7 is low and pin 6 is near zero.

This condition, indicating high drive voltage and low output voltage, occurs only when the output is grounded. If the
output of U4BA is low for the time sufficient for C26 to charge, then U4C latches low activating the protection switch
Q1 and lighting the indicator CR1. The output of U4C is held low by CR14 and will reset only after the power is turned off.