Rolling Bars on new LCD--Help Diagnosing Interference

[FLMike]

I just put in a new Samsung LN52A750 LCD to replace my Samsung DLP that failed due to a reset-loop flaw. I was very happy with the image quality on the DLP and never had any real image quality issues other than the normal cable stuff. However, now I am getting consistent although some-what subtle "rolling bars" very similar to the old "vertical hold" bars in my TV picture. They are alternating darker and pinker lines that scroll from the bottom of the screen to the top. This showed up in both the loaner Insignia LCD that I was given and the new 750 LCD that I have just installed. They were more pronounced on the Insignia but they are still very visible on the Samsung.

Both the cable box and my DVD are connected to my Yamaha RX-V659 via component cable and the receiver connected to component input on the TV. The bars are present on both sources. I need to get a longer HDMI cable to test connecting the cable box directly to the TV. When I power down the receiver so that no signals are recieved by the TV, the scrolling bars stop. Edit: I should alsopoint out that the bars are present even if I leave the receiver set to the cable box, but turn off the actual source which makes me think the interference is getting injected at the receiver.

Given that two different TVs and two different components through the same receiver are experiencing this, I am leaning ot some sort of enviromental interference or possibly an issue with the receiver. I have switched surge protectors and switched power outlets to no effect. Can anyone comment on typical causes of this type of artifact with LCD sets? Can anyone suggest additional troubleshooting steps or corrections?

Thanks,


Mike

 

[highfigh]

You have a ground loop. If your LCD is connected to a different circuit from your stereo and cable/satellite box, run an extension cord from the same surge suppressor as the stereo and cable/satellite box. If that doesn't do it and you have cable, unplug the cable feed from the cable box- if it goes away, you'll either need to ground the cable feed (because the cable installers usually don't) or you'll need an isolation adapter inline on the cable feed. If you hear humming in your system, it's likely that it has the same cause.

It doesn't have to be the cable box but it is a common cause. It could just as easily be the subwoofer or a motor that's close to the LCD that's causing this.

 

[FLMike]

originaly on same UPS

highfigh,
Thanks for the reply. Originally had the TV plugged into the same UPS as the Receiver and the cable box and had same issue. I moved the TV to another outlet and surge suppressor with no change. But they are on the same internal circuit for the house. Where can I get the type of isolation device you are suggesting? I will try the cable disconnect you suggest.

Mike

 

[lsiberian]

http://www.jensen-transformers.com/iso_vid.html

Model VRD-1FF

This is the AH recommendation. It costs a bit, but it's exactly waht you want if the cable has the issue.

 

[FLMike]

Thanks!

I just realized I accidentally posted this in screens and projectors and it should have been in TVs. So thanks for the replies. I took your advice and disconnected the cable and it cleared the issue completely on other sources. I found the article on ground loops in tips and tricks last night and ordered the VRD1FF this morning. It will be here tomorrow and hopefully I will be enjoying clear viewing for the weekend!

Mike

 

[highfigh]

You didn't say if you have cable or satellite but the Model VRD-1FF indicated that it won't work with satellite TV. Otherwise, Jensen are among the best.

 

[lsiberian]

You didn't say if you have cable or satellite but the Model VRD-1FF indicated that it won't work with satellite TV. Otherwise, Jensen are among the best.

lol I would hope he doesn't confuse the two.

For satellite you have more control.

 

[FLMike]

I have digital cable

Yes, I have cable. And the item is clearly marked on the site that it will not work with Sat. I'm just happy I don't have to spend the weekend methodically disconnecting and reconnecting to isolate the issue.

Thanks,

Mike

 

[FLMike]

Issue Solved

Just to close this out for anyone who runs accrossthis thread later, the unit solved the issue completely. Jensen was great to work with. I installed it over the weekend and the picture is awesome. If you run into this with your equipment give their product a serious look.

Mike