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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Sun Feb 20, 2011 4:32 pm Post subject: Marquee VNBs |
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I have some questions about Marquee VNBs.
Are there differences between color channels in VNBs? On my Marquee 7500 all VNB looks the same and on each stickers a red and blue signing. But on my 9000 the green tube is a slightly different VNB (on it's sticker there are red, green, blue signing) but it has TLP2531 (white) optocoupler instead of HP2531 (black) on others.
I ask this because I have an issue with the 9000's green VNB. The G2 needs to be turn down to around 40-41 to not see the raster, but in this case the overall brightness of the green so low that I cannot able to do a proper grayscale setup. Not the tube weak because if I turn up the G2 to 50-60 I get very bright picture, but the raster also clearly visible -so somehow the contrast capability of the green is very weak.
I changed the VNBs from the M7500 and the green G2 needed to turn up around 50-60 to get a normal picture, but in this case the the contrast was right (the raster still unseen at G2 70-80)
Beside that to throw away the old VNB can you suggest something to look for?
Other question: what is "auto clamp" good for? On the M9000 it does noting, but on the M7500 does the picture unwatchable (the bright areas appears to black and noisy)
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Mon Feb 21, 2011 4:31 pm Post subject: Re: Marquee VNBs |
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| gjaky wrote: | | I have some questions about Marquee VNBs. Are there differences between color channels in VNBs? On my Marquee 7500 all VNB looks the same and on each stickers a red and blue signing. But on my 9000 the green tube is a slightly different VNB (on it's sticker there are red, green, blue signing) but it has TLP2531 (white) optocoupler instead of HP2531 (black) on others. |
there is no difference between cards of the same vintage. Basically there's the old ones with metal-can transistors which should be replaced, especially if they use the CL409 op-amp, and new VNB's which stayed pretty much the same from 1995 to 2005+.
| gjaky wrote: | | Beside that to throw away the old VNB can you suggest something to look for? |
a new set of VNB's is your best bet. I have a nicely re-built and lightly modified set ready to go in the FS section.
https://www.curtpalme.com/forum_archived/viewtopic.php@t=24723.html
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Fri Feb 25, 2011 4:24 pm Post subject: |
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I can swap from my 7500 the VNBs they are newer, but I think the VNBs of the 9000 are very late editions (....-07P iss.8-9), equipped with HFA1100s.
Anyway I found out what was the problem, the G1 drive went out because the L1 smd inductivity was open. Tonight I'll do a comparision between the two set of VNBs 
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