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Discussion Starter · #1 ·
I have recently installed a Yamaha DPX-1 and notice a line scrolling through my picture. I have the unit mounted from the ceiling and the line scrolls from the bottom of the screen to the top. A second scrolling line appears just prior to the first leaving the top of the screen.


I've tried both component and composite inputs from satellite, vcr tapes, and DVDs. The problem is consistent.


As a newbie, is there something simple I am missing which can be taken care of via set-up or is this an indication of a defective projector? Any advice would be appreciated.


:confused:
 

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This is often a sign of power interference, i.e., 60 hertz hum. The scan rate and the hum rate are just different enough to cause the line to go rolling down your screen. If this is happening, you would see another line start at the top just when a line disappears at the bottom.


1) Does this affect all program sources?

2) Try connecting directly between sources and the projector. Move the source (e.g., DVD player) up close to the projector. Try different cables. Check the signal path.

3) Cheap cables or cheap switching devices can cause this problem. I have also seen it on cable TV, where you will have a difficult time getting the cable company to fix it ("within specs", they say).

4) If this persists, having tried the above, it could be the projector itself. Check your sources into another device device (e.g., a different projector or TV) to see if the sources and/or cables can cause the problem with another display device.


This is usually just a matter of isolating the defective components.


If you want to get decent cables at a good price, try

http://www.bettercables.com




Bob Smith
 

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I had this with my Sanyo and found that if I got one of those 2 prong to 3 prong adapters and put it in between the projecter plug and the wall, the problem went away. The problem you described can be caused by a "ground loop" which this simple fix eliminates.


Dan
 

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Sounds like a ground loop problem. I just installed a Sharp 9000 and had the same problem. I solved it yesterday.


My ground loop was caused by my cable TV coax -- the most common cause. I fixed it by converting my cable from 75 ohm to 300 ohm and back again. These conversions prevent the cable ground from reaching your home theater system. I used Radio Shack cat. #'s 15-1140 and 15-1253.


More information on ground loops:

http://siber-sonic.com/broadcast/GLoopFix.html
http://www.smr-home-theatre.org/Ground-Loops/
http://www.epanorama.net/documents/g..._building.html
 
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