I have a strange problem and wonder if anyone can help,

I recantely had a power cut whilst watching tv in my bedroom,
I was watching via RCA from the dreambox on a channel on my motor which is on a diseqc switch port number one. Now after the power cut the RCA has sound but no picture and the diseqc port one is broken (all other ports are fine). I have replaced the diseqc switch just to be sure and all is fine apart from the RCA? I have also reflashed the box just incase, any help will be much appreciated.