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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Wed Jul 13, 2016 10:38 pm Post subject: Marquee Neck Board Noise Problem - Blurred Lines Fix Mod |
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Over the years I've been talking about one day finding a fix for this problem.
The problem is not usually visible on screen, but can be seen using the right source, scope and test procedure.
I'll need to set this all up using my test bed and demonstrate what the distortion looks like and also show how it affects the image. I'll do this using only a 60mhz scope, that's really all that's needed when using the right procedure to look at the signal. I use test patterns to see noise, so this may be a good learning for some who would find this hard to beleive. And that"s why I'll do a setup and demonstration to show what it looks like and where to address it, and how to make it go away. I'll even fire up my Marquee on the ceiling and I'm sure the final results would be visible even using screenshots.
Anyway, this will take a few days to pull it all together. And I'm not sure if or what it would do for a stock video chain, but for sure it takes my Mods to another level.
I call it the Blurred Lines Mod, because it solves a Blurred (scan) lines problem, that I never knew existed until finding this fix. very necessary and important for 1920X1080P - and I'll even show a part of a scan line that's normally distorted and will also show what it looks like on the scope after the fix. But the screen is where the real end results will be seen... so I finally solved that problem, with me only having to finish the complete filament turn off. And I will..
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cmjohnson
Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s
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Link Posted: Wed Jul 13, 2016 11:21 pm Post subject: |
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I'll be watching this with interest.
It seems to me that any blurring of scan lines is going to be due to jitter in the vertical deflection system. Jitter in the horizontal deflection system would not blur a scan line, but it would have the same visual effect as reducing available video bandwidth.
But such noise may come from any source that affects where the beam is landing. Including focus, including astig. Including convergence, too. ALL those circuits need clean power and I'll bet that they could all benefit from additional shielding in a few critical areas.
With the Marquee chassis, you've got your work cut out for you, as it doesn't have as robust a shielding system as the other top projector types.
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Thu Jul 14, 2016 1:19 am Post subject: |
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cmjohnson wrote: |
It seems to me that any blurring of scan lines is going to be due to jitter in the vertical deflection system. Jitter in the horizontal deflection system would not blur a scan line, but it would have the same visual effect as reducing available video bandwidth |
Both vertical and horizontal are stable, with the tiniest jitter not even being a problem. The smpte (both vertical/horizontal) looks good on the screen, and stable in the video chain, so no problem there.
Quote: | But such noise may come from any source that affects where the beam is landing. Including focus, including astig. Including convergence, too. ALL those circuits need clean power and I'll bet that they could all benefit from additional shielding in a few critical areas |
Yes they can, but as long as they are stable and for the most part they are good. PLus I have years of trying to improve the focus dealing with a cleaner supply. Was able to make some change, but not enough to keep at it.
[quoteWith the Marquee chassis, you've got your work cut out for you, as it doesn't have as robust a shielding system as the other top projector types.[/quote]
Yes, but I'm more near finishing things at this point. Once you consider it was not designed for higher resolution use, or for the 1080P we like and gives the best image. If that would have been the goal, they may have done even more.
The fix I've developed deals more with a distortion that's created at the neck boards and put right into the image. And I'm going to show you what it looks like and hopefully how it affects the image on my screen. My setup has greatly improved in clarity, depth and finer image detail even in the backgrounds
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Thu Jul 14, 2016 1:31 am Post subject: |
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Ive posted a few shots last week from my setup, that has an not yet setup green LCP tube and red and blue LUG.
I'm going to fire up the setup using the exact same everything to include not touching any of the adjustments.
i'll be back
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Thu Jul 14, 2016 2:38 am Post subject: |
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Some shots taking using my Iphone6. The green LCP tube needs a glycol change as well as the magnetics has not been setup. Only static focus, so this setup is far from prime time
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Thu Jul 14, 2016 11:24 am Post subject: |
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I'll need a better camera for this. The Iphone ain't working as expected, and i'll need to find my charger for my other camera.
Anyway, below is a part of Step Pattern generated from the CLM, using the output from the VIM to the scope (direct no probe). I use my generator for this, because it produces a cleaner pattern (16/32 step).
Later I will connect a neck board using a probe, and scope this same internal test pattern showing the distortion on that same signal. I will switch to an analog scope and show what's on the mini RCA connector (input) and at the same time show what the distorted signal looks like in comparison to the source. I will also show in comparison what the source looks like after the fix. I will scope the final on the neck board at pin 8 (cathode) of the CRT.
Hopefully later I'll find my camera charger, but may not be able to use the camera to show the difference. I would say the difference on the screen is more depth and image detail opposed to better focus overall, though the focus is improved but not well seen in a static image.
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cmjohnson
Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s
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Link Posted: Thu Jul 14, 2016 1:56 pm Post subject: |
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I'm just specualting here, but I suspect that there would be advantages to be gained in amplifier linearity if all the transistors on the neck cards
were closely matched and levels adjusted fo the most linear range of operation.
But we know it woiuld be difficult at this stage to match the output transistors. Who wants to volunteer to carefully remove all the transistors from dozens,
maybe hundreds of neck cards, sort and match them, and then reinstall them in sets and then trim the whole neck card for max linearity?
The time for matching those output transistors would be when they were all brand new in trays, fresh from Motorola, before installing them.
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Thu Jul 14, 2016 2:25 pm Post subject: |
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Unlike audio stages, video stages are not critical on matching transistors. If you ran the most critical linearity test, and found problems, the fix or solution never has anything to do with the transistors. This can be verified with any set of neck boards that show linearity problems. If the problem exist separate from the other two boards, it's a bad component. And when it exist and the components are not bad or defective, it'll be consistent on the other two boards, which should rule out transistors.
The step patterns are a good test for linearity, but that's on screen. The best in circuit test for linearity is a really good ramp pattern. The ramp makes it easy to see the linearity performance when scoped.
However, the step pattern also serves well for noise, but that's all in how you use it and where.
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Fri Jul 15, 2016 12:10 am Post subject: |
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My days will be full through the weekend, so it'll be awhile before I can set this all up and do a good demo of what I've mentioned.
But in the meantime, anyone with a scope and access to the neck boards, fire up yor set and post a few shots showing what the internal step pattern looks like when measuring from the cathode and/or G1 of either Green or Red CRT.
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Fri Jul 15, 2016 2:43 pm Post subject: |
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Wow, I'm stunned that not one of the Marquee owners with a scope has scope either of those CRT pins using the Internal Test pattern for source.
Seems to not be an interest in this, so I'll not waste time going forward, because I really have a lot on my plate right now. But if you guys do happen to get around to doing this test. Compare what the source looks like to the final.
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barclay66
Joined: 27 Jun 2011 Posts: 1291 Location: Germany
TV/Projector: Marquee 9500 Ultra
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Link Posted: Fri Jul 15, 2016 4:33 pm Post subject: |
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Sorry, but do You expect all of us jumping off our seats in a day's timeframe? So, please allow us to:
- Being online at the time You wrote it
- Finding this thread
- Reading it
- Making necessary preparations (not all have extender boards)
- Getting those measurements
- Documenting them here
Did I forget anything?
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cmjohnson
Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s
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Link Posted: Fri Jul 15, 2016 6:41 pm Post subject: |
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I don't currently have a working oscilloscope to use for that anyway. Got lots of scopes that I need to see if I can fix,
but none that are fully operational at this time.
Make no mistake, I'm interested in this but that doesn't mean I can really actively participate at this time.
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Sat Jul 16, 2016 12:43 am Post subject: |
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barclay66 wrote: | Sorry, but do You expect all of us jumping off our seats in a day's timeframe? So, please allow us to:
- Being online at the time You wrote it
- Finding this thread
- Reading it
- Making necessary preparations (not all have extender boards)
- Getting those measurements
- Documenting them here
Did I forget anything? |
The thread has been here since Wednesday, so we're several days beyond your days time frame. And it's still here, so you can see if there's any interest for you. And if so, at your convenience you can look at what it's all about and if you follow what I posted, you should be able to see a noise that's should also be in your video chain.
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racerxnet
Joined: 20 Jun 2007 Posts: 362 Location: Illinois
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Link Posted: Sat Jul 16, 2016 1:31 am Post subject: |
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mp20748 wrote: | barclay66 wrote: | Sorry, but do You expect all of us jumping off our seats in a day's timeframe? So, please allow us to:
- Being online at the time You wrote it
- Finding this thread
- Reading it
- Making necessary preparations (not all have extender boards)
- Getting those measurements
- Documenting them here
Did I forget anything? |
The thread has been here since Wednesday, so we're several days beyond your days time frame. And it's still here, so you can see if there's any interest for you. And if so, at your convenience you can look at what it's all about and if you follow what I posted, you should be able to see a noise that's should also be in your video chain. |
Mike,
Your post title States a "Fix". Not a guessing game as to what the "Fix" is. Not bashing your efforts, just stating what appears as someone throwing out a rope and then pulling it back in. If there is indeed a fix for a problem, just state what is needed and where related to the noise. Simple and straight forward.
Hope you have a great weekend.
MAK
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Sat Jul 16, 2016 3:12 am Post subject: |
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It's all about interest. I said my days would be full through the weekend, the weekend just got here. I also ask for anyone with a scope to try this and post results, so far nothing.
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Tim in Phoenix
Joined: 21 Oct 2006 Posts: 4378 Location: Phoenix
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Link Posted: Sat Jul 16, 2016 4:16 am Post subject: |
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Okay
So why exactly is this 'invisible problem" a problem?
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greg9518lc
Joined: 19 Apr 2016 Posts: 360
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Link Posted: Sat Jul 16, 2016 2:34 pm Post subject: |
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_________________ VDC 9518LC modded: I do not sell or promote mods only interested in the best PQ possible......
Last edited by greg9518lc on Wed Aug 03, 2016 2:37 pm; edited 2 times in total
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mp20748
Joined: 12 Sep 2006 Posts: 5681 Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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Link Posted: Sat Jul 16, 2016 6:31 pm Post subject: |
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Tim in Phoenix wrote: | Okay
So why exactly is this 'invisible problem" a problem? |
It's there Tim.. invisible on screen, but nonetheless still there.
I was hoping one of the techie marquee guys would simply scope pin 5 or 8 on a working neck board using the internal step pattern, so you could see what the distortion looks like. But I'm also sure anyone seeing it for the first time would be trying to figure it out. And no, you don't need extender cards or anything else beyond a scope with a probe and a working marquee.
I had stopped using high bandwidth scopes to advance my work years ago. I've been doing everything using a 60mhz analog and 50mhz digital scope. The magic in it all is knowing how to use very unique test patterns.
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gregstv
Joined: 27 Aug 2007 Posts: 628 Location: Australia
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Link Posted: Sun Jul 17, 2016 4:54 am Post subject: |
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While we are waiting for those Marque guys, here is the Barco. No internal so I used an old AVAI DVD. Its all I could find in a step pattern.
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cmjohnson
Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s
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Link Posted: Sun Jul 17, 2016 2:07 pm Post subject: |
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Calman doesn't have step patterns? I think it does, and more than one of them.
I'm just curious as to why you're chasing a "problem" we can't see when there are other more visible problems that could be looked into, like ways to reduce the crosstalk between channels.
Bring up a menu that should only appear in the green channel, for example, and you'll see a ghost of it in the other two. At least you'll see it on the tube face if not the screen.
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