Thursday, July 7, 2011

QSC 1400 Amplifier repair

I recently purchased a non working QSC 1400 amplifier.  A few seconds after being powered on the clipping light comes on.  I downloaded the schematic and started checking voltages.  The +15 and -15 volt power in one channel measured at pins 4 and 8 of the op amp was only +9 and -15 volts.  I traced out the power and found +9 at one end and 0 volts at the other end of a 3.9 volt zener diode.

This picture shows the location of the zener in the schematic;

here is the location on the circuit board:
Post a Comment