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Discussion Starter · #1 ·
Hi everyone,


I was wondering if anyone would care to offer some troubleshooting tips or typical causes and/or resolutions for what is best described as a blueish, purplish faint horizontal line slowly scrolling vertically (from bottom to top) across the screen. The setup is an Infocus IN76, attached directly to a Denon A/V receiver via Component video (RGB) cable (Mini RG59 coax, 30ft max). Attached to the Denon is a DirecTv H20 via a 6 ft molded component cable.


Is this a grounding difference issue? Or maybe an interference issue with the cable running from the AV receiver to the PJ? Any other ideas?


Thanks in advance for any help offered.


Sincerely, Roger
 

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Yep, ground loop issue. Test with a 6 ft. component cable by bringing your DVD player closer to the PJ and this shoud go away. If so, get a good 30 ft. component cable (best you can afford) and this should go away. Bang-for-buck, Monoprice is great. Why are you not using HDMI for your DVD? Video should bypass the Denon receiver if possible and just use the Denon to switch audio if you can. IN76 has multiple video inputs so you may not need Denon to switch your video.
 

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Discussion Starter · #3 ·
Thanks very much for the response Huey!


Quick question for you, if you don't mind. And this is a question based on my ignorance only....If it's a ground loop issue, then I thought that was caused by a difference in ground for the electrical connection for the PJ as compared to the electrical connection for the AV receiver? If that's the case, how will running a new (better) component cable resolve this? I assumed, maybe incorrectly, that this would require an electrical resolution, no?


In general, should I not use the Denon rcvr to switch video? The Denon rcv is an AVR-887, so I was planning on replacing the current RGB connection with HDMI just to see if that resolved the problem. But I was planning on still using the Denon to provide video switching between the H20 and the DVD-1930, which also has HDMI. But you're saying that if possible, don't ever use the video switching capabilities of rcvr's? Is this just to ensure no degredation of the source's video signal when runing through the rcvr? Again, all honest questions based on my ignorance....


Thanks again very much for your reply and I really do appreciate your insight and help.


SIncerely, Roger
 

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HDMI should reduce the interference being digital. Just get a decent cable like those from Monoprice designed for your distance. The less connections the better so yes if you can bypass the receiver which may introduce artifacts and interference into the chain, the image will be stronger, cleaner, and more stable. It's always best to avoid switchers if you can and let the PJ switches between HDMI, component, Svideo, and composite. If you have 2 HDMI sources then you'll stuck with switchers.


I'm not sure what is causing your interference, but the easiest troubleshooting is to bring your DVD player closer to your PJ and test it with a shorter component cable (free) before going to Ratshack and buying a ground loop isolator or AC line filter (not just surge protector but they make one to filter or condition your AC line).
 

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Try plugging your projector into the same outlet the rest of the equipment is plugged into using an extension cord as a test. Also try plugging the projector in to its outlet using a cheater plug. The type they sell at hardware stores for adapting a 3 prong plug to a 2 prong outlet.


Those are two good simple tests that if the scrolling line goes away you can be pretty sure it's a ground loop problem.


Below is a good read on ground loops. That came up a week ago. In that thread I linked another good read.

http://www.avsforum.com/avs-vb/showthread.php?t=782636
 
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