behringer pmp3000 cannot get left main to sound

[jackieblack]

I have an amplification selector that starts with MAIN L - MAIN R
Then the next one has a selector for .............. MON1 - MONO
The final choice is..................................... BRIDGED AMP MODE

The first one is supposed to allow you to hook up 2 PA speakers and hear one on the left and One on the right. The problem is that all I hear is music, and voices on the "Main R" side.
The only time the other speaker can be heard is when you switch the selector swith to MON1-MONO or God forbid "BRIDGED AMP MODE" which I do not think yuou are supposed to do this.. Any suggestions or Ideas for why this is not working woul really help....and YES I have turned the pan switch back and forth to see and that does nothing,,,,

John
ajwestbury@sbcglobal.com

[Enzo]

OK, so no output from the MAIN L side when in L/R mode. But Monitor signal does come out that speaker when in Mon1/mono, right?

Ther are two power amp insert jacks. Plug a test signal into each. We already know the Main R side works, does the other power amp work? it should, based upon your report. Ther are main out jacks on top of the mixer. Not the speaker connections on the rear now. ther are in fact two sets of them. Run a cord from one to another amp - is the signal coming through. Now plug into the other one. Coming through? We just tested the L and R outputs of the mixer section.

If the mono signal from the mains comes out the one side, apply an input signal to a channel and bring up the master and mono faders to hear it. Now spin the pan pot left and right on the input channel. Does the sound remain on both sides, or does it fade out to one side? That tests if the channels can send a signal to both left and right.

My guesses would be a dirty contact in one of those patch jacks up there upper right, or perhaps a bad side to the main fader.

[jackieblack]

I am no genious at this, I can tell you know what you did helped. It does seem that these are made to be used in the mono/monitor selecter or bridged because otherwise it will only produce like 200 watts which is nothing when you use it in a band setting. In attempting to hook it up the way you had said, I finally got somethinhg to come out but I could barely hear it. When I used the opposite right main it was a little stronger, but the harder you pushed it (even though you could hear it a little better) it was very distorted like it was not made for just using it for the mains unless you have a separate power amp to help it along.
Anyway, I just wanted to thank you as I will probrably get a couple of monitors and use it that way app-wise so that I can try and get the full 1200 watts out of it. I do have a schematic on how to try and do this, but if you have any suggestions they will be extremely welcome and helpful I am sure.
I am a musician that has played fo over 29 y-rs but I still tun into these things from time-to-time.
Anyways---all my thanks---John K. Westbury

[Enzo]

Not sure what I was right about.

Are both left and right main signals OK at those MAIN OUT jacks up top? Does sending a signal into each power amp in jack produce a strong output in the speakers?

The two amps in it are rated 300 watts each with an 8 ohm load, and 600 watts each with a 4 ohm load. That is when fully driven. You don;t need special setups to get it, you just need to drive it all the way with 4 ohm loads.

The power amps have no idea where in the mixer the signal comes from. The left/right setting puts one amp on each buss. the mono/moniotr setting puts the LR mix on one and the monitors on the other. the amps don;t behave any different. If your master section is not sending a full signal to the amp, then it can;t put out a full signal into the speaker.

[jackieblack]

When I hooked up cords from the main outputs on the top- I got the same thing. I hooked my guitar into channel 1 and the used a cord from L Main out....I could hear it...barely...after I turned it up all the way. Then I moved the cord from the L Main to the R main and it almost blew my guitar amp.
Again, this is on Main L- Main R Amp Mode.
What can I do now other than just use it as a Mono- Monitor amp mode (secod selection)
I also tried moving it to the out below for mains 1 and 2 and both of them seem fine as well. It is called "Main2", but there is no such thing in the back of the unit......do you have a picture of my unit?

[jackieblack]

If you look at the picture of the board there is a "mains 2" radio dial. I decided to hook up the speaker cords to the "mains 2" outputs below the "out put 1's". Now sound comes out of both sides -even panned- but alot lower than what it should come out like.... No something must be wrong or dirty in the power amp all the way around.

[Enzo]

Better than that, I have one sitting here.

DOn;t confuse the jacks on top with the jacks on the rear. The stuff on top is ALL in the mixer. The speaker connections on the rear are power amp outputs.

let me get it straight.

Main 1 L doesn;t work.
Main1 R works.

Main 2 L&R BOTH work?

Both Main1 and Main 2 come from the same signal source, they are each individially driven out those jacks. SO if main 2 L works, we could patch it to the L power amp.

Did you follow my suggestion about the MONO and the pan pot on the channel?

I think what you have is a dead op amp at one point in the circuit.