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Rdean
Joined: 13 Oct 2006
Posts: 258
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| Posted: Wed May 28, 2008 2:57 pm Post subject: Low output Marquee green tube |
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I just put together my go forward Marquee, a below 2000 hr M8000 that now has the neccesary parts to make it a an 8500. The tubes have no wear. After I put it all back together it fired up to my suprise! But the green tube has low output at low contrast levels.
Here are the current levels:
Drive G2
Red: 27 64
Green: 94 70
Blue: 23 70
If I take contrast down to below 20 the green has no output at all on tube face while red and blue show plenty of output. Any contrast below 45 and the stairstep pattern's middle bars are pink.
Is this green shot even though it has less than 2K hours? Is there anything else besides the tube itself that would effect the cutoff level of the tube?
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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: Wed May 28, 2008 2:59 pm Post subject: |
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Check your filament voltage. Swap neck cards. Swap video feeds from the VIM. Swap G2 leads between tubes. You need to narrow down whether this is a tube problem or something that's driving the tubes.
If your filament voltage is over 6.5 volts, then it quite possibly could be the tubes, but check everything else first.
Cheers!
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Rdean
Joined: 13 Oct 2006
Posts: 258
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| Posted: Thu May 29, 2008 3:07 pm Post subject: |
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Filament voltage @ 6.4, I assume that is OK. Swapped video leads and the problem followed the leads. So I swapped out the VIM and problem solved. Thanks!
Now another issue: All 3 tubes flicker (get slightly dimmer for split second) in unison. This is intermittant but often enough to be annoying for sure.
I tried swapping out the HVPS (2 of them) and the LVPS. Also swapped out CLM. Nothing fixed it. What should I try next?
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