Diagnose my signal interference - new projector install - AVS Forum
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post #1 of 9 Old 04-23-2001, 06:27 AM - Thread Starter
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OK gang, this past weekend the new Infocus LP350 was installed on the ceiling, the electric Greyhawk was also installed. My install crew used (2) coax in place of (1) S-Video cable, due to the length of the run, approx. 27'. They used an MIT cable on each end that converted the (2) coax and "Y" them to (1) S-video connector to go into the Infocus.

I am getting a faint horizontal line that rolls upward from top to bottom. Before it reaches the top, another new faint line starts rolling again up, from the bottom.

Much appreciated,

Dave

Is this anything anybody here on the forum can diagnose so I can tell my install crew what to do?
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post #2 of 9 Old 04-23-2001, 06:33 AM
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Most likely is a ground wire problem.

What kind of power cable are you now using ? Is it different from before ?

You can get a power conditioner and see if something get better or you can try to eliminate totally the ground wire for the projector.

The problem can also be the AC wiring of the DVD player or AV receiver.

bye

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post #3 of 9 Old 04-23-2001, 11:49 AM
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Sounds like a classic ground loop.

Do you have cable tv? If so, disconnect the cable antenna feed from ALL of your AV equipment and see if that solves the problem. If it does, you need an isolation transformer, best I've seen is from Jensen Transformers. I happen to have some in stock, I give them to my customers if they have this problem.

If not cable tv, then it's harder to solve. The best solution is proper grounding, but that probably means opening up the walls and rewiring all of the related outlets (using a star ground). Sometimes lifting a ground on a power cable can help diagnose the problem, but I don't recommend this as a permanent solution.

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post #4 of 9 Old 04-23-2001, 12:52 PM - Thread Starter
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by mmcdlc:
OK gang, this past weekend the new Infocus LP350 was installed on the ceiling, the electric Greyhawk was also installed. My install crew used (2) coax in place of (1) S-Video cable, due to the length of the run, approx. 27'. They used an MIT cable on each end that converted the (2) coax and "Y" them to (1) S-video connector to go into the Infocus.

I am getting a faint horizontal line that rolls upward from top to bottom. Before it reaches the top, another new faint line starts rolling again up, from the bottom.

Much appreciated,

Dave

Is this anything anybody here on the forum can diagnose so I can tell my install crew what to do?
</font>
Guys, i should have emntioned I am using a Monster 3000 power conditioner. The power cord is not the actual cord supplied with the projector - but it is an identical twin. It has the same connector at both ends, is also 6' long and same diameter. You wouldn't be able to tell them apart. The original is misplaced, and this one was laying around so we used it.

Dave

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post #5 of 9 Old 04-23-2001, 04:30 PM
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Dave I used to get similar scrolling lines when any dimmer switch in the house wasn't all the way on or off, but with a power conditioner, you should have eliminated that possible source - just a thought

Andy
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post #6 of 9 Old 04-23-2001, 05:07 PM
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As Wm suggests:
If disconnecting the CATV from the input to the residence does not solve your problem, you are better off using an isolation transformer as it specifically addresses the problem you are describing. To confirm that it is a ground loop I would consider using a cheater plug (3 to 2 ac adapter). If this eliminates your slow moving 60hz bar, than I would consider going with an isolation transformer. I share the success with Jensen composite vid, S vid, and line level audio products. There is an excellent white paper on their website http://www.jensentransformers.com

One other note a six dollar grounded outlet tester could confirm if your current outlet is wired incorrectly.

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[This message has been edited by Don O'Brien (edited 04-23-2001).]

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post #7 of 9 Old 04-23-2001, 06:52 PM - Thread Starter
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by mmcdlc:
OK gang, this past weekend the new Infocus LP350 was installed on the ceiling, the electric Greyhawk was also installed. My install crew used (2) coax in place of (1) S-Video cable, due to the length of the run, approx. 27'. They used an MIT cable on each end that converted the (2) coax and "Y" them to (1) S-video connector to go into the Infocus.

I am getting a faint horizontal line that rolls upward from top to bottom. Before it reaches the top, another new faint line starts rolling again up, from the bottom.

Much appreciated,

Dave

Is this anything anybody here on the forum can diagnose so I can tell my install crew what to do?
</font>
Thanks to all for the replies - I will give ALL of this info. to my install crew this week when they come back!

Dave
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post #8 of 9 Old 04-23-2001, 07:22 PM
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good info.

I am having the same problem.

Sure hope it isn't the dimmer problem. I have two in my HT and they are completely necessary.

I already have one of those cheater plugs in my HT set-up. Now it looks like I need another. I hope I don't get a raid by the UL anytime soon.

-Mr. Wigggles

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post #9 of 9 Old 04-24-2001, 12:19 AM
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The best fix for grounding problems is a "star" or communications ground... Not a simple thing to do, though, unless you have the walls open, since it requres rewiring all the outlets. If you are in the process of constructing your theater, however, you owe it to yourself to do this. Anyone who has visited here can attest to the results.

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