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js100
Joined: 27 Apr 2008
Posts: 9
Location: BERGEN,NJ
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| Posted: Thu May 08, 2008 5:07 am Post subject: Help. NEC brightness issue |
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Just replaced my green tube on an xg 1351 and the picture looked dark. After a while it became bright and the brightness control does not work. The contrast control does work. Maybe I knocked a wire loose someplace. Anyone have any ideas what I should check?
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Thu May 08, 2008 5:57 am Post subject: |
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Yes! Check the multicable running next to the blue tube going to the card cage motherboard, somewhat behind the blue tube. If that's knocked loose, it will kill the brightness control. I've done it twice while changing tubes..
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Thu May 08, 2008 12:28 pm Post subject: |
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Or the big red G2 cable has come off...
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js100
Joined: 27 Apr 2008
Posts: 9
Location: BERGEN,NJ
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| Posted: Fri May 09, 2008 2:05 am Post subject: |
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I checked all the connections and it did not make a difference. Very confusing because everything else works fine except for brightness control. The picture looks pretty good but slightly too bright.
Which is the big G2 cable? Can I get around this by lowering the bias or gain on all three tubes?
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Fri May 09, 2008 3:56 am Post subject: |
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Brightness doesn't work when the test/normal switch is in test.
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js100
Joined: 27 Apr 2008
Posts: 9
Location: BERGEN,NJ
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| Posted: Fri May 09, 2008 4:10 am Post subject: |
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That sounds like it could be the problem. Where is the switch?
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Mark_A_W
Joined: 15 Mar 2006
Posts: 3068
Location: Sunny Melbourne Australia
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| Posted: Fri May 09, 2008 4:15 am Post subject: |
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It's on the Gain board, or maybe the Video Out board, I forget.
You can see it through the metal card cage. It's not likely to just "move"....you can't bump it.
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js100
Joined: 27 Apr 2008
Posts: 9
Location: BERGEN,NJ
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| Posted: Fri May 09, 2008 4:32 am Post subject: |
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The switch was in normal position. I tried moving it back and forth but it made no difference. Curt, any ideas?
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dropzone7
Joined: 12 Jun 2007
Posts: 1069
Location: Charlotte, NC
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| Posted: Fri May 09, 2008 4:58 am Post subject: |
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I know this is kind of like saying "you need to reboot your computer" but perhaps try reseating the boards in the card cage.
_________________
"Coffee is for Closers."
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Fri May 09, 2008 12:46 pm Post subject: |
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If indeed there are no loose connections, then I'd suspect a problem on one of the video cards on the left side of the card cage (floor mounted). I can test them all for you and repair/replace as required.
Other than that one loose connector, I haven't had that before.
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js100
Joined: 27 Apr 2008
Posts: 9
Location: BERGEN,NJ
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| Posted: Fri May 09, 2008 7:00 pm Post subject: |
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I think I will take you up on your offer Curt. Which boards can I swap out with similar boards while my boards are being repaired and tested?
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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