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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Sun Feb 22, 2009 4:17 pm Post subject: BG808s - left-edge brightening on red |
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I've been tweaking on my 808 since I got a bluray drive (nothing like good content to force a better setup  ) and have noticed a highlight on dark-to-light transitions on the red tube.
I've checked the source: Green doesn't have the problem at all, but if I run green into the red input, the problem still exists. So the issue is after the input stage at the PJ.
I dug around on teh intarnets and found mention of an issue with the 1208 wherein a certain component would go, causing highlighting, dark-ish vertical banding on the left side, and a slight nonlinearity on the left side. I seem to have those things to some extent, but I'm not sure whether it's enough to suggest that that's the problem.
Ideas? Thanks!
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Gary M.
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| Posted: Sun Feb 22, 2009 6:23 pm Post subject: |
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that is ringing of some sorts, may be a problem in the signal chain inside or outside the PJ, could be anywhere sad to say 
check your cables/outside the PJ first, switch around and see if the problem moves
it could very well be what you found on the 1208 issue
-Gary
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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Sun Feb 22, 2009 11:58 pm Post subject: |
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Like I said, I checked the signal by swapping R and G cables. Problem stays with tube rather than moving with cable, so it's internal to the PJ somewhere.
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perisoft
Joined: 29 Aug 2007
Posts: 2920
Location: Ithaca, NY
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| Posted: Mon Feb 23, 2009 1:02 am Post subject: |
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Turned off 'peaking'. Bright edge gone - it's perfect now.
Increased porches in power strip - vertical banding on left of image gone.
That was a productive 15 minutes of CRT tweaking!
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Mon Feb 23, 2009 7:21 pm Post subject: |
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| perisoft wrote: | Turned off 'peaking'. Bright edge gone - it's perfect now.
Increased porches in power strip - vertical banding on left of image gone.
That was a productive 15 minutes of CRT tweaking!
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I was about to say that it's peaking problem, but you figured it out yourself.
That peaking setting should be always off.
There is still quite much off peaking in circuit, not sure why they use those pF caps to all over boards...
I gues that's part of that "120MHz" thing.  (how to get 120MHz out of 80MHz chip.)
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Gary M.
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| Posted: Tue Feb 24, 2009 9:37 am Post subject: |
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I should have said that as well, it was my first thought but figured you had turned that off already
Barcos can have some nasty peaking if you want it
-Gary
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