Behringer PMP5000 - No power

[Dauda]

I have a pmp5000 mixer. I was trying to connect a 2nd loudspeaker to it (Output B) when I starting smelling as if something was burning. Did not realize that the board was in the Bridge mode when I was hooking up the 2nd speaker in Output B. Now the device does not power on any more. The main fuse is not blown. F1, F2, and F3 are ok. There is power at the cable that plugs into X1 and X2. Checking the pins on X4(the 6 wire cable that connects the mixer to the sps1000/02 board) there is no +15v on pin1 or -15v on pin2. Nothing on pins 1, 2, 4, and 5. Tried to run the mixer alone by disconnecting X3, X5, and X6(the two 3 wire thick cables and the 6-wire cable) from the board. Still no power to the board. Not sure if the problem lies on the HCA2400 board. Have not tested for anything on this board yet. Need urgent help desperately. Thanks.

Dauda.

[Enzo]

Yes, pulling those three connectors should allow the mixer part to run without the power amp. If they are disconnected, the4 HCA2400 is no longer in the circuit and cannot then be part of the rest of the issues. The HCA2400 may be blown and may have damaged the power supply, but once disconnected it can have no more influence.

So you have no low voltage supplies. Are the high voltage supplies present at the three-pin connetors? I forget, maybe 80 volts each? If they are there, WARNING, they hold a charge a long time, always check and discharge them during service.

At power up, do the fans kick over or spin?

Starting from sratch, check the HCA2400 for shorted outputs. Here is a simple way. Find the hot output lead, and measure for continuity from it to the +80 and -80 pins on the power connetor. A shorted output transistor will show itself that way. Shorts there may have daqmaged the SMPS.

The SMPS has a pair of 22 ohm standup power resistors, R11, R12 for slow start. A relay shorts across them after a moment. If they open, the supply will not run. And on the secondary side, just check all the rectifiers for shorts.

[Dauda]

Thanks Enzo. I will try your suggestion as soon as get home tonight.

[Dauda]

@Enzo:
God bless you. It is exactly as you described; R12 was open. Replaced it and was able to power up the mixer. I purposely left the power amp section disabled until when I have enough time to test it to make sure that there are no problems in that section. The mixer section is working and I am happy. Thanks again Enzo, you are the best!

Dauda.

[Jazz P Bass]

What I have seen on these amps is a failure of one of the output sections (left or right channel) will shut down the unit.
Now, the very next time that you turn it on is when you take out the soft start resistor.
It cannot start with a shorted output section.
The overcurrent zaps one or both resistors.