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Discussion Starter · #1 ·
My friend is having problems with his Panasonic TH-50 PHD7UY plasma, (which he bought from me last year). What is happening is he is getting a very slowly scrolling interference pattern rolling up the screen, taking about 5 seconds to complete the trip, then repeating. The pattern looks like 1" square blocks. The panel was recently moved (carefully, I was there), but he can't say whether it was happening before the move, due to circumstances. He tried several different sources (Cable, DVD, Tivo) through all the interfaces (HDMI, Component and S-Video) and the same pattern appears. It also appears if there is no source and you open a menu. I imagine it is there on a black screen, just impossible to see. We also hooked it up to a power conditoner to make sure it's not the line. This doesn't appear on any other TV in the house.

http://download.yousendit.com/5724C3F04C3565A5

Here is a video of the pattern (albeit a crappy one). Look about 5 seconds in when he zooms into the wood background. You will see what looks like a string of blocks roll up from the bottom of the screen.


Any ideas?
 

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It is hard to see with all the camera moire' but I would suspect a ground loop probably between the incoming cable coax and th epower ground of the Plasma.


Quick (and potentialy dangerous !) test - use a 3 to 2 prong AC ground lifter on the AC plug of the Plasma to see if the noise is eliminated.


If so, you may need coax RF isolators and audio isolation transformers to break the ground loop(s).


Have also seen this from economy RF amplifiers used to split RF 4 or more ways.


TW
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by Techniwizard /forum/post/14180126


It is hard to see with all the camera moire' but I would suspect a ground loop probably between the incoming cable coax and th epower ground of the Plasma.


Quick (and potentialy dangerous !) test - use a 3 to 2 prong AC ground lifter on the AC plug of the Plasma to see if the noise is eliminated.


If so, you may need coax RF isolators and audio isolation transformers to break the ground loop(s).


Have also seen this from economy RF amplifiers used to split RF 4 or more ways.


TW


Thank you for the reply. I'll pass this along to my friend. A question, were it a ground loop as you describe, would we still see it even when using the HDMI interface to a DVD player (interference is visible on every interface and any source.) Also used a UPS on the power side, ho help.


I'll let you know if the ground break fixes it.


Thanks


Mike
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by mchad /forum/post/14186296


Thank you for the reply. I'll pass this along to my friend. A question, were it a ground loop as you describe, would we still see it even when using the HDMI interface to a DVD player (interference is visible on every interface and any source.) Also used a UPS on the power side, ho help.


I'll let you know if the ground break fixes it.


Thanks


Mike


Ok, well that didn't work... And just FYI, the video should be 26sec long... I just downloaded it and tried to play in and windows media only played 1 sec of it. Quicktime played all 26. Strange?


So, what's next, just bring it in I suppose.
 

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Discussion Starter · #6 ·
So he brought it in to a Panasonic authorized repair shop and was quoted $600 for a new power supply. $600??? Does that seem right? You can buy a brand new 50" plasma for $1200 with warranty today.


That seems a bit overpriced to me, or am I wrong?


Thanks
 
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