Grant, apologies if I've put this in the wrong place.

While poking around behind my hifi and A/V cabinet, connecting a DAC to my CD player, I seem to have upset something.

The picture coming form the Sky HD box isn't making it to the TV, but the sound is getting to the speakers as normal. I should mention it goes to a Sony AV receiver, via an optical cable. When I look at the end of the cable, the end that goes into the amp, there's a red light, so something is coming through.

Eventually, as I was desperate to get to the pub, I ran a HDMI lead from the Sky box to the amp, to get it running. But I'm not sure if I have a problem with the optical cable, the Sky box or the amp (all about 7 years old now).

Any thoughts on this would be much appreciated.