Behringer LD6230 service manual

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And those do have an analog control input. I assume you are using the DMX512? You can feed the six channels individual 0-10VDC analong control voltages. That would be a separate way to test the amp's ability to control the dimmer channles.


And we shouldnl;t overlook the possibility of a damaged triac.
 
There is an MOC3020 optocoupler to control each triac. I assume you moved the wires to the triacs themselves.


Pins 1 and 2 are the LED inside the 3020. PIn 1 is the anode, and through a 220 ohm resistor is wired to +5. Pin 2 is the cathode and receives the controlling signal. What does pin 2 look like on the bad channel compared to the other channels. If the controlling signal is different, then we have a controller IC problem, but a bad 3020 night be the problem here.

There is also a 470 ohm resistor from pin 6 of each 3020, that goes to the triac gate. Make sure it is good.
 
I switch at flat cable comming from transfo board...Opto and triac are good. Each of the 6 chanel have a nice 0-99% 5V duty cycle, but with different phase referenced to each transfo, the phase transfo. It just seem that for wahtever reason, ch4 syncro seem to come from another reference (phase). Then, even with 1% of duty cycle on chanel 4, triac fire imediately. All other channel are sync with their reference. Ch1 and 2 are on the first transfo (phase), ch3 and 4 on second, and 5 and 6 on the last. Ch4 seem to have about 8ms of phase error compared to Ch3, wich is suppose to have same phase. Anybody know where they get reference? Is it done inside the PIC controler? Any ways to delay phase on ch4 simply? We are 60Hz here by the way...
 
There are three Zero crossing detectors, one per phase. ICs 4,3,2, type 311.

Each should handle two channels. Zero crossers 1-3 are fed to pins 2,3,4 of IC7 74HC573. Out pins 19,18,17 of that directly to IC1 pins 40,39,38.

IC1 on the control board is a PIC 16F874. The six outputs to the triac drivers are, (1-6 order) PIC pins 19,20,21,22,27,28.

If one of those is different, I don;t see how it could be anything but a bad PIC. I don;t see how the zero crosser could be out of phase for one channel but not its mate.
 
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