I have one behringer ep 4000 that has blown few outputs 1943 and 5200 and both 50n06 on one channel do to excessive heat (cooling fan failure).I replace all components and check the other channel all was ok.the time for test work both channels ok (on oscilloscope with 1khz signal) for few minutes.
Then the god channel starts rise temperature on R65-62-66-67-68 and gets really hot. After that the waveform is distorted and the signal led and clip led is on if i turn the pot to the right no more than 10 o clock and no signal at input.If the pot is at 0 all way left the leds stay off.
The repaired channel it works normally.doing detailed check again and found nothing broken.Change all output devices one by one to be sure there is no defect.No luck the channel have the same behavior.
Any tips where to look-check?
Thanks for any info.
Then the god channel starts rise temperature on R65-62-66-67-68 and gets really hot. After that the waveform is distorted and the signal led and clip led is on if i turn the pot to the right no more than 10 o clock and no signal at input.If the pot is at 0 all way left the leds stay off.
The repaired channel it works normally.doing detailed check again and found nothing broken.Change all output devices one by one to be sure there is no defect.No luck the channel have the same behavior.
Any tips where to look-check?
Thanks for any info.
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Hi full speed,
This amp has a very unusual design--- I'm still trying to understand it.
Is the pot you refer to VR7A, "INPUT GAIN"? This seems like a clue. Do internal bias voltages return to normal when the pot is at 0? Look at the input to the pot--- there should be no DC and no AC, i.e. defective C15? oscillation at IC4R? Poke around with your scope and look for abnormal readings, especially oscillation. Be sure to use x10 scope probe to avoid cap loading of circuits. Use working channel for guidance.
Let us know about anything you find. Good luck!
This amp has a very unusual design--- I'm still trying to understand it.
Is the pot you refer to VR7A, "INPUT GAIN"? This seems like a clue. Do internal bias voltages return to normal when the pot is at 0? Look at the input to the pot--- there should be no DC and no AC, i.e. defective C15? oscillation at IC4R? Poke around with your scope and look for abnormal readings, especially oscillation. Be sure to use x10 scope probe to avoid cap loading of circuits. Use working channel for guidance.
Let us know about anything you find. Good luck!
Here is some improvement.After looking very carefully with magnifier glasses and take some measurements with DMM i found a tiny hair short in one pin of the 4580 ic4.That was my mistake when i solder the new chip.Now the amp starts normally with clear waveforms on booth channels and no rising temperatures on thermal camera.Thank you very much for advice bsst.Later doing the tests under load.