My Behringer Eurorack MX2004A occasionally ceases to transmit signal from one or more of its input channels to headphones or to main out. I would like to try to figure out why to see if it is something I can fix or avoid.

  • Sometimes wiggling a mute button (in and out) will temporarily fix the problem.

  • Perhaps more revealingly, sometimes just making a loud noise into the channel (nothing extreme, just tapping the mic with my hand) will also "bump" the channel back into life.

Could this be dust inside the mixer or is it likely something more serious? Happy to run some tests if anyone has any suggestions for things I can try. I wish I had more information, but as it is an intermitten problem, it is a bit hard to debug!


3 Answers 3


I think the best you can do is contact Behringer about this model.

I doubt it's dust, from what you describe.


In general, if you are not an electronics service engineer, there are two approaches.

  1. Strip it apart & bathe it liberally in contact cleaner.

  2. Take it to a service engineer.

1 covers dust & dirt, 2 covers component failure.


Two possibilities for analog lockup: phase inversion and/or engaging input clamp diodes on an opamp can cause a DC lockup. High frequency oscillation can cause an AC lockup. The latter will typically register significantly on the volume meters, the former not. Either may be triggered or ended with input disruptions.

A digital lockup is unlikely to be cured by input disruptions.

Lockup may be a sign of overcritical design or bad components, or of unsuitable components (swapping opamps for more modern types is a popular pastime but can cause instabilities).

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