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Old October 30th, 2007, 11:10 PM   #1
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Rolling line on Projector at Church

I think I've found the problem...I need help with the solution.

We have 3 Projectors set up in our sanctuary, all of them have a nice slow line rolling through just enough to bother people.

And then I turn off the lights...and no rolling line (to bad we don't have church in the dark)
Of course all of our lights are controlled from evil Dimmer Switches.

I have tried boosters, different computers, new cables, video mixer, different power supplies etc.
But I believe the answer lies in the lights.

Is there some sort of filter, box, whatever, that can be hooked into the computer, lights, projector, that would eliminate this awful rolling line.

Any suggestions would be wonderful!

Thanks in advance!

Jason
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Old November 2nd, 2007, 02:28 PM   #2
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I have a friend who does this for a living, he has a solid home theater business and is the know-it-all guru in our church when it comes to audio/video. Contact him via www.georgiahometheater.com and tell him to credit my account for the referral (just kidding).
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Old November 2nd, 2007, 02:58 PM   #3
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Hi Jason..........

Just so that I can get a handle on the specifics with this one, could you outline exactly what is connected to what, how (analogue, digital etc), distances, and all that sort of stuff.

That mains powered flouro/ dimmer controlled lighting can play havoc with data/ video systems is not new. The secret is knowing just how and where the emf from the mains circuits is getting into the food chain.

With the little I have to go on so far, my main suspect is the cable runs from whatever feeds the projectors to said projectors, especially if the cable runs are anywhere near the mains lighting circuits.

Even that theory has to be taken with a pinch of salt, as emf can feed back to the main distribution board and appear on just about any mains circuit in the entire building. If the projectors themselves have inadequate filtering on the power supplies, it can be coming in via that route instead of the data/ signal cableing.

That all three units show the same falt symptoms does, however, point a finger of suspicion to something shared - the device feeding said projectors, perhaps.

You can see now why these sorts of problems can be a devils own job (sorry about that!) to sort out.

Hmm, Exorcism, anyone?


CS
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Old November 2nd, 2007, 03:32 PM   #4
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More thoughts.......

OK, no lights, no line?

Can I assume, as you have dimmers, that the lighting itself is incandescent, not fluoro, gas discharge, something from outer space?

Probably worth firing up all dimmer controlled circuits, one at a time, to see if it's only one particulr circuit giving the problem. If so, try changeing the dimmer for that circuit.

If you turn the dimmers full up (max brightness) does the line fade/ dissapear?

If so, it's most likely the dimmer(s).

If any and all dimmer controlled circuits give rise to the problem, can you by - pass the dimmers? (ie. is there an "override" switch?). If there is no override, do you have a friendly electrician who can by - pass the dimmers temporarily (simply connect the "mains in" to the "mains out")? If they can all be bypassed (lights full on) and the line is still evident, it isn't the dimmers.

If it is every single dimmmer, there would seems little else but to replace them with higher spec units (try just one first) to see if improved filtering kills the problem.

If it isn't the dimmers after all (and they are indeed incandescent lights), think it's going to get a bit tricky.

That should keep you going for a while.


CS
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Old November 2nd, 2007, 04:03 PM   #5
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and more..........

If it is definately nailed to all the dimmer circuits (ie. each one will give rise to the problem when activated) then it is most probably a combination of poor dimmer circuitry giving rise to excess RFI and inadequate filtering before the dimmed power exits the dimmer caseing itself.

If changeing every dimmer for higher spec'ed units is starting to look like a very expensive option, there is one thing you (er, well, a competent electrician, anyway) can try, which is much cheaper and realtively easy to do once you know what you're doing.

Go down to your friendly local electronics store and purchase a plastic coated ferrite torroid about 1/2" to 3/4" in diameter. Remove dimmer panel from the mounting box and disconnect the O/P (from the dimmer) feed to the lighting circuit. Wind the [insulated] O/P wire (you may have to lengthen it with a joiner if there isn't much slack) through and around the torroid ring 3 or 4 times, and re - connect the wire to the O/P terminal of the dimmer.

This should seriously nail 99% of RFI getting past the filtering in the dimmer itself. If you can stop it getting out of the mounting box, job done. Just monitor the toroid and wire windings under full load to ensure it isn't getting hot (shouldn't do, 60Hz has little effect on a ferrite torroid, RF does).

That lot should keep you going for even longer......


CS
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Old November 2nd, 2007, 04:21 PM   #6
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todays final installment...

Dredgeing the memory banks, these RFI traps can be purchased "pre wired" with specific load ratings to suit the circuits in use. It might be a better option to use these on both I/P & O/P leads on the dimmer unit, they'll probably do a better job than the home made version.

Again, a competent electrician "should" know all about them.


CS
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Old November 4th, 2007, 09:41 AM   #7
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Well I got some work to do, I will keep you posted on my results
Thanks for all the suggesions
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Old November 7th, 2007, 04:12 AM   #8
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Hi Jason......

How's the Exorcism going?


CS
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Old November 7th, 2007, 10:29 AM   #9
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I have sent the information to my electronic guru at church
I will let you know how it goes, thanks again for the information
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Old November 22nd, 2007, 12:29 AM   #10
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Hi Jason........

How's the electronics guru doing?

Should have been able to re - wire the entire Chuch since the last post.

CS
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Old November 25th, 2007, 07:29 PM   #11
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Ahh...working at Church

Well when you do things at church, they have these things called committees...therefore, my suggestions (thanks to you) are now going through the committees that be...so I will keep you updated as things happen!
Hopefully by the end of the year, so patience I must have.
Thanks again for all your help.
Jason
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Old November 26th, 2007, 11:14 PM   #12
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Blimey..............

I figured you'd just dive in there one night after work/ Saturday morning with an electrician mate and give it a shot before going the full catastrophe and dismantling the entire Church (or whatever it is the "committees" are discussing).

Maybe I got the scale wrong - this is smaller than the Houston Astrodome, isn't it?


CS

PS. It is the "Houston Astrodome", isn't it? (Biggest stadium in the US? Hey, don't ask me, I'm a Kiwi).
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Old November 27th, 2007, 06:49 AM   #13
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Aaah, the power of commitees!

Chris, sounds like you never had to deal with one. Church commitees are the perfect killer of all perfectly good projects. You have an idea? Bring it to the commitee, it will surely get killed there.

I should know... I run the audio/video ministry at my church. The worship commitee tells me what to do, when to do it, and how to do it: where to place cameras, how to move them around, how to use the lights, etc. We have a "sensitive eye" choir director, she went to the commitee and got approval to have the lights dimmed a bit when she's up there... who cares it doesn't look good on my video?

I hope Jason's commitee is more technically oriented.
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