Behringer MX802A Phantom Power Buzz

[gomanvangough]

I have a Behringer MX802A Mixer a few years old with a loud 60hz buzz when the phantom power is switched on. It's noticeable with condenser mics but overwhelming when other (non-phantom powered) devices are plugged in. It's getting progressively worse with time suggesting a bad filter capacitor. I download the schematic but it lacks the power supply.

Question: Does anyone know what the problem is (I'll bet it's a power supply capacitor) or the availability of a schematic for the power supply?

 

[kid klash]

Well, since the power supply is a wall wart, you could try a different but identical wall wart to see if it solves your hum problem. My guess is that you've got a cable problem, maybe between the mixer output and your recorder/monitors, or a mic cable problem... all of which could cause the hum you're speaking of. If that's not the case, then open up the mixer, and look for any electrolytic caps in the path of the wall wart's connector, and replace it/them.

 

[dgatwood]

There's either a bad cap or the problem is elsewhere. Since it has a wall wart, my bet is elsewhere. Try disconnecting it from all other gear and only hooking it up to the mic and a pair of headphones. If the hum goes away, the problem is not in your mixer.

 

[T Sat]

You could even try it in another outlet. it could also be a grounding issue.