Cerwin vega XLS 12s

I'm having a problem with the 12s, when it gets a LFE signal the sub starts but after 1-2 sec it starts to crackling and popping non stop.
Even if i remove the LFE cable it continues so it won't go to standby again, i have removed the standby PCB and reflowed it but no success.
Does anyone have a service manual or have experienced this before and fixed it?

/Daniel