Problem with Behringer ub2442 Preamp

[dryman]

a friend gave me an ub2442 for repair. The problem is, that the mic-preamp isn't working properly. If you put a signal in the xlr-in, you can't set gain correctly, because if you raise the gain pot, the signal doesn't increase in the same manner, but not long before the end of pot, the signal raises into clipping.
What make me wondering, is that this is happening on all channels. I checked the voltages, but they seam to be okay. Can anyone help me where i can find the error?

 

[joaquins]

The pot would be my first guess, try putting resistors in parallel with it when gain is at minimum... then you could add a smaller pot in series to get better control in the highest gains.

JS

 

[dryman]

i will try that. I would also guess the pot, but i was wondering, because the problem appears on all channels. But it is connected via connector, maybe that is the problem.

 

[joaquins]

they don't use the best pots, so something may happened to the device, dust or shaking and they show this problem... if the supply measures ok for voltages and voltages with high signal passing, so it works good with some signal I don't know what else could be happening... how old is the device? something happened to it?

JS

 

[dryman]

I changed one gain-pot against a new pot and every thing works fine. All of the gain-pots are damaged, they are very poor quality manufactured from Behringer it self. But they have the same size, than Alps pots. Thanks for your hint joaquin.

 

[joaquins]

It's nothing.. Good to know it's easy replace that makes this UB working again, I have an ADA8000 and I'm looking some way to mod those pres...

JS