HD 600/4 JL

One of the SMD cap across the output terminal is badly burnt (c236 anyone know the value?
Q1 and R1 doesn't have the parts install.Is that normal or missing?

The left rear channel in this amp is not producing output and the output FETs for the right rear channel is heating up.I see no drive signal coming to the driver IC for the right rear channel.I pull the IC ,signal still not present on the input of the IC.Any suggestions?


2010-06-22 6:08 pm
After i pull the components i get 6v on the RR channel.

I did not check for DC before i pull them because the amp was in protect. With the driver IC out of circuit shouldn't i see a square wave signal on the pads for the IC input?
That is what i see on the working channels.

Perry Babin

Paid Member
2003-11-20 11:01 am
A square wave input is only going to be present when the amp has essentially no DC offset and the outputs would be driven alternately. When there is DC, the feedback circuit drives full DC to the driver on whichever input that would remove the DC if the circuit was complete.

Sometimes you can get the DC low enough by shorting the two output terminals for the defective channel. It probably won't bring it close enough to 0v to get a perfect 50% duty cycle but it may allow you to see the square wave input.

If you decide to short the terminals, do so carefully. I'd recommend doing it through a dummy load resistor. When you short them, the current draw from the 12v supply shouldn't change significantly.