[tico]

Hi, I don't have too much experience with the HDTV stuff, but I have a strange recurring problem that maybe someone can figure out. The TV is a 56" JVC rear projection DLP, 1080P. When I connect the XBOX via HDMI and then select 1080P or 1080I on the XBOX, the TV will periodically develop vertical lines that remain on any input, even cable TV input. I need to power off the TV and repower it to get them to go away.

I since tried it on component video, 1080I and the strangest thing, the lines actually appeared while I was watching cable TV at the instant that the X-Box (connected to component inputs) went into it's "hibernate" mode.

With the X-Box disconnected, this never happens. I can't see how the x-box could be triggering this, especially when connected via two different input methods.

Any ideas?

 

[57]

There may be some electrical ingress coming through the XBOX connection that shouldn't be there. Perhaps the XBOX is not properly grounded, or there's something wrong with the XBOX itself. Only certain signals should be going through the video cables and if you've got more voltage due to some sort of "leak" within the XBOX, it can damage the TV.

 

[tico]

There might be something there, I hadn't thought of the potential correlation of my weird ground loop problem elsewhere in the house. I have a 4 channel modulator that runs my non-HD sat and a few other devices via coax throughout the house. I had a problem with the IR extenders (communicates back to the modulator over the same coax) when - get this - my Polaroid LCD is plugged in (on or off), the coax is connected to it (or the ground of the coax is touching it) and when the Air Conditioning compressor is running. You want to know how long it took me to figure that one out? I temporarily fixed this by cutting the ground prong off the Polaroid thinking that it must be the TV. Maybe I've got ingress or bad grounding on my coax network - my X-Box, being properly grounded might create a path for it. I'll recheck all my grounds on the coax network.

Thanks for the nudge in the right direction, hopefully I'll find something.

 

[57]

"Fixing" a ground loop by using a fancy power bar or cutting the ground plug is asking for trouble. The improper ground needs to be found and rectified before there's damage to equipment or people.

 

[tico]

Yes, I agree that removing the ground isn't a "fix" - I told the wife that the remotes work now, just don't (physically) touch the TV upstairs. I was only half joking.

I still have the same weird ground problem (and possibly the X-Box problem) after rechecking that my cable provider's cable is grounded to earth ground outside the house, again inside the house.

Today I added a new ground wire (to the same earth ground connection point where the wire to the CATV provider is run from, also my main electrical service is grounded to). Now my sat switches (4 in all) and my 2 modulators, along with 1 three-way CATV splitter and 2 diplexers are all grounded to the same point with one contiguous piece of bare copper #12AWG.

AC still interferes with IR when the Polaroid is connected -- and it's worse than just interfering, it "overloads" the IR emitter causing the emission of a steady IR beam and makes every IR remote in the house not work - like a jamming device. I will have to check out the X-Box to see if my other problem is repaired...

 

[57]

Now that you mention IR issues (not the original topic), here's a thread that may be of interest - read all of post 1 since it's more than LCDs....

http://www.digitalhome.ca/forum/showthread.php?t=64463

 

[tico]

I know we are going off-topic, I hope that is tolerated to some degree in this forum as my issues may be related. I had read that thread previously which is why I jumped at your idea of ground loop (seeing as I had IR interference and had just read that thread). But I originally dismissed the advice in that thread because just being plugged in (with a ground prong) is enough for the Polaroid in combination with the AC to "max out" the IR signal and basically jam all other IR signals (IR uses a 5V carrier over the coax). The TV doesn't even have to be on ... only the AC compressor (AC Fan only is OK). Also interesting is that substituting a 13" CRT, plugged into the same outlet (grounded) and wired to the same coax does not cause this issue. Would not the chassis ground in both the LCD and the CRT be Earth ground (third prong)?

What I promise to do (to get us back to the original topic) is play X-Box within the next few days with all Coaxes disconnected and all other video sources disconnected to see if it could be ground related between X-Box and JVC.