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How I fixed InFocus X1 grounding woes


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#1 of 5 JasonGabler

JasonGabler

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Posted April 12 2005 - 08:29 AM

After learning about ground potential differences and reading a few articles on HomeTheaterForum and other places, here was my original problem and here's how I fixed it:

When I first set everything up (Infocus X1, Motorola digital cable, Sony HTiB, non-HD TV, and Playstation2) I had _two_ horizontal lines slowly scrolling up my screen from grounding issues, one stronger than the other. I could even see the weaker line on the TV when the X1 was on but not projecting. Then i also had a sea of diagonal lines from power interference. Even with component cables I made from twisted pair cat5e the problems weren't solved (cat5e has no shield, although the signal itself was somewhat better overall). Anyhow...

Originally, I kept my X1 ungrounded with an outlet adapter. Not only did this not help with diagonal lines, it left my expensive projector unprotected from power spikes, etc.

The first thing I did was to ground the CATV shield. Fortunately the power outlets in my apartment are (for the most part) properly is grounded and the CATV line comes through the floor near one of them. It was late at night so I didn't run to RadioShack to get a CATV grounding block ( radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-909 a mere $4), I simply soldered a wire to the outter connector of the CATV line and then crimped on a terminal to the other end which I put under the center screw on the faceplate of the outlet. Bam! The more prominent horizontal line was gone!

In one fell swoop I got rid of the second horizontal line and all the diagonal lines. I purchase a 25ft VESA<->Component RCA cable on eBay. ( I also just found them on the Web here: cablemakers.com/hdtv_svga_cables.htm ) A Python double shielded 25ft cable only $25! The thing worked WONDERFULLY! I am guessing because of proper chasis grounding on the cable the last horizontal line went away on the projection screen and on the TV. Then because of the good quality shielding all the horizontal lines disappeared. I had my old cat5e cables quite far from power sources and in-wall power lines and nothing helped like the proper shielding on the Python cable. Even when the electric city buses and trains roll by, its crystal clear.

I hope this helps someone.

jason

#2 of 5 John S

John S

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Posted April 12 2005 - 08:47 AM

Always good to post your solutions indeed.

This ground / interference stuff can drive a body absolutely bonkers. I deal with this sort of thing alot.


I will take heed of the simple cable grounding method. Sounds logical and I must admit, I have never thought of it before. I always try to go back to the cable source and solve the ground issue there, but your method is way way easier than that and I'll bet just as effective.


Great job!!!

I know people get tired of us always suggesting this or that with grounds and better cables, but your experience pretty much nails home why we so often do that here, because so often these sorts of things really are the cause.

#3 of 5 Ralph B

Ralph B

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Posted April 12 2005 - 08:57 AM

I agree. grounding is important.

as for surges....I do have a over 3000 joules surge protector but just incase I just unplug the projector on the projector end when its done. easy to do and doesnt screw up settings. that for sure is best protection. I even unplug my SVS when done.

#4 of 5 JasonGabler

JasonGabler

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Posted April 12 2005 - 09:42 AM

John,

the problem with CATV is that you cannot address grounding issues at the source. Remember the source isn't your cable box, but the source of the CATV signal itself at your cable TV provider's station. I also suspect that the thousands of other subscribers, if not just the ones in your building, somehow contribute to line and grounding problems. My hypothesis is that when you set a ground for the cable wire before it hits your equipment, you drain that potential. Incorrect theorizing or not, though, it works in practice Posted Image

jason

#5 of 5 John S

John S

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Posted April 12 2005 - 12:29 PM

Well. Source was to strong of a word for sure.

There is supposed to be a grounding doohicky somewhere on the building / house. Posted Image