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deronmoped
Joined: 03 Nov 2006
Posts: 1154
Location: San Diego
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| Posted: Thu Nov 08, 2007 5:15 am Post subject: Ground loop? |
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Can displays (PJ's, monitors, TV's...) suffer from ground loops? I have been taking care of some hum from ground loops in my audio equipment and that has me wondering if it can affect my PJ.
Deron.
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zaphod
Joined: 16 Jun 2006
Posts: 2002
Location: Cloverdale
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| Posted: Thu Nov 08, 2007 6:55 am Post subject: |
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ground loops can cause hum bars and other video effects.
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picree
Joined: 31 Mar 2006
Posts: 351
Location: Johnson City, TN
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| Posted: Mon Nov 12, 2007 2:46 am Post subject: Re: Ground loop? |
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| deronmoped wrote: | Can displays (PJ's, monitors, TV's...) suffer from ground loops? I have been taking care of some hum from ground loops in my audio equipment and that has me wondering if it can affect my PJ.
Deron. |
Yes they can. I just solved one tonight as a matter of fact. I've heard that a ground loop can sometimes manifest itself as a slow rolling wave or blip moving up or down the screen...most noticeable on a uniform background image. I had an extra 14 ga. wire I ran from the CRT chassis directly back to the ground in my main circuit box. It never seemed to have any negative (or positive) effects until recently. I can't think of anything that changed but in the last month or so I noticed this little wave slowly (3-4 seconds) creeping up the screen. I lifted that extra ground wire and it stopped immediately.  So, more grounding isn't always better I guess. 
Curt
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MAIN THEATER: (JVC RS2000; Yamaha UDP-LX500; Yamaha RX-V2400; Lumagen Radiance Pro, Vertex)
SECOND WII-ATER: (BG808; WII; Oppo 971H; Moome external box; BG-DVI transcoder; tse gamma box; Extron)
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Mon Nov 12, 2007 9:32 am Post subject: Re: Ground loop? |
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| picree wrote: | | I've heard that a ground loop can sometimes manifest itself as a slow rolling wave or blip moving up or down the screen...most noticeable on a uniform background image. |
My BG1200 have similar faint scrolling bars all the time and I haven't get rid of it yet. I have always source in same socket etc.
My other PJ's don't have this problem with same source and in same wall outlet. (same thing in two department)
Just found out that BG1200 power input board (main) have isolation transformer, that looks little fishy. In theory this is good thing, but in practice it could cause my problem.
Any other Barco I know don't have isolation transformer in power input board. Otherwise power input board is like in 1209, but it have this transformer. So I'm going to remove it and add two caps, so then board is upgraded to be 1209s power input. 
Hope it helps...
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deronmoped
Joined: 03 Nov 2006
Posts: 1154
Location: San Diego
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| Posted: Mon Nov 12, 2007 5:44 pm Post subject: |
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I wonder if ground loop problems (showing up in the image) cured by isolation power supplies is why some people swear by them.
Deron.
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