HDMI cable "No Signal"

[Headhunter]

My cable box is Scientific Atlanta Explorer 4250HD.
New TV is WestinghouseTX-47F430S.
When connecting with HDMI cable I get 'No Signal" on all of the 4 TV HDMI ports. Connecting with component cables works fine.
I swapped out the cable box, no joy!
HDMI worked the first night 2 weeks ago and has not worked since then
I'm baffled. Any suggestions anyone?

 

[e2727]

Only think that i can think of is to try another HDMI cable

 

[Chucky Cheese]

If you have a DVD player with HDMI out and don't get a picture, it's a set problem. Use component cables instead.