I have an XBOX 360 Arcade Jasper and I´ve been using it with a Samsung Syncmaster P2370 for a couple of years now. It´s a Full HD LCD monitor. I use with it an HDMI 1.3 cable (1080p). I´ve also tried it with a 32" RCA Full HD LCD TV, with no issues.
Now I´ve bought an LG LE 5550 32" LED TV (Argentina) and the TV, with the same cable and the same console, says NO SIGNAL. The TV has 4 HDMI ports and I´ve tried all of them (they all work with my PC and using the same HDMI cable). I changed many times the
console configuration to lower resolutions; I´ve even done it "blindly", counting the movements (some claim this works). I tried reseting the console to factory default (Y + Right Trigger while starting it with no disc inside). I deleted the cache. I tried
starting the XBOX with the RCA connection and then changing to HDMI... I tried 2 different cables... I can´t think of anything I haven´t tried.
I´m already (so sadly) thinking of buying a component video cable... Please excuse my english.