I'm posting this for future reference as I found no repair info online.
circuit board is p0572 pcb904080revc
I had one dead main output on this mixer.
There is a heat sink on the side connected to 3 voltage regulators: +12V -12V and 5V. If you have all voltages there should be no need, but I flipped the heat sink around to be able to access the circuit board underneath.
My problem was a bad solder joint in the opamps around the master fader. IC22 is directly before the master fader, IC23 is directly after the master fader. Outputs of IC23 is connected directly to R204 which is a quad 3k9 resistor pack.
I remelted the solder joints on all these parts as well as the master fader and gave the fader a good squirt of tuner 600 and it was back in business. Hopefully this will save a couple of these units from the trash pile.
EDIT: Also, gain adjustment on ch1 did not work. It was the actual gain potmeter. 5kC05 is printed on the board, so so it should be a 5k reverse logaritmic.
circuit board is p0572 pcb904080revc
I had one dead main output on this mixer.
There is a heat sink on the side connected to 3 voltage regulators: +12V -12V and 5V. If you have all voltages there should be no need, but I flipped the heat sink around to be able to access the circuit board underneath.
My problem was a bad solder joint in the opamps around the master fader. IC22 is directly before the master fader, IC23 is directly after the master fader. Outputs of IC23 is connected directly to R204 which is a quad 3k9 resistor pack.
I remelted the solder joints on all these parts as well as the master fader and gave the fader a good squirt of tuner 600 and it was back in business. Hopefully this will save a couple of these units from the trash pile.
EDIT: Also, gain adjustment on ch1 did not work. It was the actual gain potmeter. 5kC05 is printed on the board, so so it should be a 5k reverse logaritmic.
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On my Behringer mixers I have replaced the undersized and hot heatsink by a new aluminum plate occupying the whole bottom. I did also glue new feet for better heat dissipation.
That is a good idea - that heat sink gets rather hot. It does not seem to have caused any problems so far, but probably will in the future.
