Ecleree PAM2600, Service Manual

Page: 16 / 107

13
CLIP CIRCUIT
The other half of IC307(4001) is used in the clip circuit. Given that we have two gates more and we just
need one for our purposes we will connect them in parallel for a higher output current and a more effective LED
lighting up.
The clip threshold or point where we want the LED to light up is determined by the zener D313. In our
case it is between 0.5 and 1dB or, what is the same, when the output signal level over the load reaches a value
close to that of the power supply (+V), exactly Vout = V - 5.6, moment in which Q304 loses the base-emitter
voltage stopping conduction; this makes the zener D312 voltage disappear (0V) and the output from IC307 go to
"1" logic (+10V), making the LED light up.