Hi I have a behringer eurolive 415 dsp 600w PA speaker, its making a hum noise when I turn it on, also when it's turned on it makes a load pop noise and pushes the sub out, the top speaker works fine but I get minimal sound from the 15" I'm guessing because its pushed out and stays there..
How can I fix this, I seen about testing for DC offset, it must be the problem but how can I fix it?
How can I fix this, I seen about testing for DC offset, it must be the problem but how can I fix it?
sounds like the internal power supply for the bass speaker has faulty capacitors, probably some other issues as well in the driver circuit.
Thus the Hum and Pop.
My assumption at this stage, if this device has only just started to exhibit these faults is to have it repaired by a competent person. DC Offset is done as part of commissioning when the amplifier circuit is made and the amplifier bias is done when the amplifier is commissioned, again an assumption, if the amplifier module id D class it's all a little different.
Thus the Hum and Pop.
My assumption at this stage, if this device has only just started to exhibit these faults is to have it repaired by a competent person. DC Offset is done as part of commissioning when the amplifier circuit is made and the amplifier bias is done when the amplifier is commissioned, again an assumption, if the amplifier module id D class it's all a little different.
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If the woofer cone is pushed out and stays there your amp definitely has a problem. DC offset is a small amount of DC at the output terminals that is not desirable, but also not a big problem, and not typically enough to see visible cone movement. What you have is a BIG problem, much worse than just a bit of offset, it's quite a bit of DC. Not a great idea putting that through a speaker.
I agree with checking internal fuses, but unless you know your way around such things, it's off to a service center, partly because if you find a fuse blown, you might change it, but you haven't found out why it blew either.
Get the amp serviced. No other options.
Please look at the above photos, could this be the problem, I think it was blown from the guy who owned them before me. he plugged them into a powered amp.
"Get the amp serviced" is not a option its too expansive and I would rather fix the problem myself, I know enough about what each component is and have the tools to fix it. just need to know what to look for and what might be the problem.. if I stuff them up no money lost as I got them for free from a friend "the one that stuffed them"...
Ok, great. Got a DVM? A 'scope? Oscillator? Desoldering tool? Some means of measuring distortion? Just for starters....
I think the service manual idea would be a good start. And the second point might be...be ok with making it worse if you've never fixed one of these before.
Not sayin' you can't, or won't. Just being realistic.
STOP!!!
Turn it off.
If your speaker moves one way and stays THAT IS DC ON THE SPEAKER. This will destroy the speaker. Work without a load until you have the amp stable and not making DC.
I agree with the above comments, this is not "DC offset", this is plain old DC on the output. Offset means a small difference.
I suspect the reason you get tweeter music, but not woofer music, is that there are separate amps for each, The woofer amp is blown and the tweeter amp is not.
In your board shot, I don';t see any rail fuses, so I assume you only have the mains fuse. SO you see the various transistors mounted in the big "hole" in the middle of the board? I would start by going around the rim of that hole and testing every transistor there. I'd also expect some of the smaller parts were damaged, like that resistor. Resistors do not burn on their own, so some semiconductor associated with it is also bad. You need a schematic.
If you do not have the relatively advanced technical skills to repair this board, I recommend taking it to a qualified shop.
Turn it off.
If your speaker moves one way and stays THAT IS DC ON THE SPEAKER. This will destroy the speaker. Work without a load until you have the amp stable and not making DC.
I agree with the above comments, this is not "DC offset", this is plain old DC on the output. Offset means a small difference.
I suspect the reason you get tweeter music, but not woofer music, is that there are separate amps for each, The woofer amp is blown and the tweeter amp is not.
In your board shot, I don';t see any rail fuses, so I assume you only have the mains fuse. SO you see the various transistors mounted in the big "hole" in the middle of the board? I would start by going around the rim of that hole and testing every transistor there. I'd also expect some of the smaller parts were damaged, like that resistor. Resistors do not burn on their own, so some semiconductor associated with it is also bad. You need a schematic.
If you do not have the relatively advanced technical skills to repair this board, I recommend taking it to a qualified shop.
More pictures of the amp, everything looks fine expect that resistor..
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From the user manual, there is a 300W woofer amp and an 80W tweeter amp.
The two amps are on the same pcb, and they share the heat sink as well.
If you trace the tweeter and woofer wires back you will see, and there are also
separate power supplies for the two amps.
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Enzo I will test each transistor in the middle of the board tonight but just from looking at it and giving it a good old smell I cant find anything wrong with them. As for finding a schematic for the board is probably going to be impossible to find, I cant even find a replacement board for the other amp as the pcb board is burnt.
One last shot here....
Look at the second photo, at the resistor being pointed out.
Is it burned out or just burned?
What value is it supposed to be?
What value is it now?
Where is it in the circuit, and what function does it serve?
What other component failure could have caused it to burn?
If all the other components seem ok, is the circuit oscillating ultrasonically?
Is the amp operating with high distortion, or not?
You need to be able to answer all of these and more.
I'm giving you the same reaction I get when I tell my mechanic I'm going to do my own car repairs. Sure, I can do some successfully. And some I lack the tools, experience and documentation to even start.
Expanding ones limits is a good thing. Knowing what they are is even better.
Look at the second photo, at the resistor being pointed out.
Is it burned out or just burned?
What value is it supposed to be?
What value is it now?
Where is it in the circuit, and what function does it serve?
What other component failure could have caused it to burn?
If all the other components seem ok, is the circuit oscillating ultrasonically?
Is the amp operating with high distortion, or not?
You need to be able to answer all of these and more.
I'm giving you the same reaction I get when I tell my mechanic I'm going to do my own car repairs. Sure, I can do some successfully. And some I lack the tools, experience and documentation to even start.
Expanding ones limits is a good thing. Knowing what they are is even better.
Jaddie I'll tell you all the parameters soon. As for the resistor its burnt out "gone". I just checked the bottom of the pcb all circuits look good. No burns.
Yeah, I don't need to know the parameters. I'm just trying to show the kind of job it is and the tools you'll need to do it.
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