Behringer Eurorack MX 1804X DSP FX Problem (Video Included)


Standard Member
I recently purchased this desk at a fairly good price from Gumtree, had got it home to find the effects unit to be faulty, I'm guessing this is possibly a power issue but not too sure, as the LED is not lighting up for the unit.

Thought I would share this with the forum (for more experienced technicians to view) and if possible anyone who is qualified to offer advice I would be greatly appreciative.

also I do slap my own wrists for putting the PCB's directly onto the carpet, sorry! im a **** for doing so :facepalm: .........mind you it's already fecked........but hope to find out the issue with the effects unit as do not have the budget to buy another desk.

will really appreciate any input anyone has please.

thanks a lot.

the video is linked below.

Mixing Desk Problem - YouTube

also managed to find the user manual but a datasheet or service manual would be much better for this unit.
Last edited:

Zac Ross

Standard Member
Dear Zorgan,

BEHRINGER does not supply service manuals for end users. I recommend contacting the CARE department for warranty assistance. You can contact us by phone at (1) 702-800-8290 for the US and Canada and (44) 1562 732290 in Europe.

You can also contact our CARE department via email at [email protected]. You may locate parts and technical support as well.

Hope this helps!

Kind Regards,
Zac Ross
Jr. Admin, Tech Support


Standard Member
hmmm thanks Zak, thanks for the reply, I do think this is out of warranty this mixing desk as it's probably a few years old now.

also even if I sent off for the part it would probably cost a fortune and this is why I was really wanting to attempt to locate this issue and repair myself.

But I will try to call the phone number next week and hopefully somebody can offer some advice.


Distinguished Member
Have you checked if it is getting power? It looks like it has its own on board voltage regulator and power supply, so meter this and see if you are getting a stable supply with respect to earth. The number on the regulator will give you its voltage, so 7805 is 5V, 7812 is 12V etc. 79xx is a negative regulator, but this is likely to be a singled sided supply.

Next step is scope out the audio and see if you are getting a usable audio input. My guess from the high noise floor however is that the unit has been over driven or even zapped with a voltage spike and the board is fried, with multiple component failures.

Cheapo effects units can be picked up very cheaply and sound so much better than the internal reverbs, so just find yourself an external unit and patch it in.


Standard Member
thank you so much for these troubleshooting steps, I will test using your advice and get back to you soon thanks again! noiseboy72 !!! :thumbsup:


Standard Member
okay checked the values on the voltage regulator.......7805 is labeled on the component.

3 pins each reading the following



Distinguished Member
Sounds a bit low, as if the supply is being heavily loaded down. I am sticking with my first hunch of lots of fried components.

Next step is to look at the audio in and out with a 'scope and see if you can see if it disappears into a chip, never to return! if so, this might be your cause.


Standard Member
Noiseboy I get a scope tomorrow, can't wait to find a project to learn to use the scope on......this could be it!!


Novice Member
Zorgan I know this thread is kinda old, but I just have the exact same problem with the effects processor on this mixer... did you ever find what the problem was? Found a solution?

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