Rolling Shimmer Interference on Security System

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argutus Participant Join Date: Jan 2011 Posts: 2	Rolling Shimmer Interference on Security System 01/03/2011 4:23 PM
	Hello, I have a 4 camera security system. 24v and 12v. I started seeing a rolling band, very slow moving bottom to top of screen. Looks like backwards C's )))))))))))))))))))))))))))) - like this ))))))))))))))))))))))))))))))))))) -- rolling very slowly. This interference only occurs on the two primary left and right camera's. The other two are 12v front door, Back door and they are fine. I noticed that if I pull out either the left or right camera bnc connector from the DVR the interference leaves. But when both left & right are in, it will come back again. I have 4 bnc wires from wall plate to DVR. have replaced all. But interference still there. Any Ideas on how to fix this and what could be causing it? -Tom
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frankd20 Guru Join Date: Jan 2007 Posts: 787 Good Answers: 52	#1 Re: Rolling shimmer interference on security system 01/03/2011 4:46 PM
	The rolling bands you describe are very typical AC interference. The AC could be getting into the signal in many different ways. The most common way is that the video wire is not shielded enough and is running near power lines. It is also possible that your power supply that powers the cameras is not clean. You can try and filter this out with various methods or clean the power supply output with inductors and or capacitors. You may also look at the video lines running to the cameras and how well they are shielded and grounded. This article on ground loops might help you http://www.fmsystems-inc.com/manuals/GNDLOOPart.pdf
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argutus Participant Join Date: Jan 2011 Posts: 2	#2 In reply to #1 Re: Rolling shimmer interference on security system 01/03/2011 7:15 PM
	Thanks frank. I checked out the link you posted. Great advice.
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Joachim Lange Active Contributor Join Date: Aug 2010 Location: Costa Rica Posts: 20	#3 Re: Rolling Shimmer Interference on Security System 01/05/2011 8:36 PM
	Hi, look in the power supply. There might be a bad capacitor.
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Anonymous Poster	#4 Re: Rolling Shimmer Interference on Security System 01/10/2011 10:46 PM
	hello my friend, the rolling band on the screen sometimes is cause by a drop in voltage going to the camera. sometimes the cameras if thay have Irs will draw too much current.Check your power supply.
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Anonymous Poster (1); argutus (1); frankd20 (1); Joachim Lange (1)

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