OBERHEIM SYNTH

Hi,

My Oberheim matrix 6 is having a strange problem every now and then: after a while (after using but also after being idle for a while) it starts outputting MIDI control change #4 (foot controller) with value 0. The result is that any synth or drum machine that I am playing at that moment, or selected in my sequencer, is muted. No output anymore. It is really bursting out this cc, stays outputting it until I switch the matrix 6 off. 

Anyone an idea?

Regards,

Aux