Sega Dreamcast troubles...

[wtuo]

OK, so I've owned a Dreamcast now for a couple of years and apart from buying a SCART cable about a year and a half ago, it's been completely fine. About 6 weeks ago it packed in, so I bought another one from eBay. This one didn't work, and would only send audio to my TV. I bought a second dreamcast to see if it was that, and even the combination of new scart cables and units I can't get it to display video. I've tried multiple TV's, multiple Scart cables, multiple Dreamcasts (!!), and I'm really lost on where I should go from here.

Would my best bet to buy another Scart cable, maybe from somewhere I can trust a little more than eBay? Or is there a way to repair scart cables?

Any help is appreciated, this is starting to cost me more than it's worth!


EDIT: Almost forgot, I tried my old RF cables and they kind of work (although the reason I got a Scart cable was that the RF lead wasn't working quite correctly (wierd interference lines etc.), but they do output video.