KRK Rokit 6 No Output

[Robin]

Hi guys,

I have a KRK Rokit 6 on repair at the moment. The speaker turns on fine, but no sound is coming from the drivers.
To start off, both sub and tweeter are fine.
There is no DC on the outputs

The amplifier board uses two amplifier IC's. The TDA5052 for the HF and the TDA7492 for the LF. Just like the one in Dave's video it also HAD the black gunk but that's all cleanly removed and main capacitors and affected resistors are replaced.

This is what I'm measuring. Everything on the power amplifier board seams to be fine. The reason why there is no output is that there is -19.25VDC (negative rail) on the MUTE pin of both amplifier IC's. To unmute it, it should be a positive voltage. The negative voltage comes from a comparator ic on the input/filter/limiter board. Which singals it compares, I don't know.

Does someone have a suggestion on why the output of that comparator is pulled low?

[Robin]

FIXED! 

The culprit was indeed that comparator. It was a JRC4580D and the only opamp I got laying around was a LM358, but the pinout matched so I threw it in. Now it works like a charm with a positive output as mute signal.