DVD/Projector Image Interference



Background: I have an NEC VT45 LCD Projector to which is connected directly to a Sony DVP-CX850D 200 DVD Changer utilising an S-Video connection (3 metres long). An LG LV800 VCR and a Cyberhome AD-L 528 single DVD player share a composite video connection to the projector. The projector is mounted on a back wall adjacent to a double power point socket; the power chord of the projector has been reduced to about 18" in length. Sound is provided by a Panasonic AV Control Receiver SA-HE9.

Problem: When playing back DVDs, TV or Videos I get picture interference - slow moving lines that move up or down the screen.

Question: a) Does anyone know what creates these lines and why. b) What is the cure as watching DVDs is marred by this problem. Other than that the complete system works well.

Many thanks to anyone who can provide the answer and put me out of my misery.:confused
Slow moving bars are "hum" bars. They are caused by earthing problem in the system. Make sure all equipment is wired to same outlet to start. Usual cause of ground problems in av systems is the aerial system. Get an image on the screen that exhibits the bars and then pull the aerial lead out of the VCR, both in and out. See if bars go away. If they don't then put them back and try disconnecting the VCR totally from the system. Isolate each piece at a time to find out where the problem is entering the system. Once you've found out which device is causing it let us know and we'll see if we can get a solution for you.

Thank you for your prompt reply. I will try your suggestions out over the next few days and let you know how I get on. It makes sense because I didn't have this problem before I added a VCR into the equation.......
I had a cross-hatching effect on Sky (S-Video) so I simplfied my setup to figure out what was causing it.

My wiring was as follows.

Sky->Scart->RGB-to-S-Vid converter->S-Vid Cable->S-VHS->S-Vid Cable->Amp->S-Vid Cable->Projector

Using just the DVD player and the projector, I tried each S-Video cable in turn.

I found the the culprit was a £15 S-Video lead bought from Comet this year. Swapping it for a £2 cheapo S-Vid cable got rid of the hatching effect.

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