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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: Sun Jul 17, 2016 2:36 pm Post subject: |
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The problem is a distortion. A distorting that directly affects the image and that is what the test pattern would show, mainly because it shows various lines at various different IRE levels. So unlike random or scrolling faint lines or other non direct image related distortions, it directly affects the image.
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gregstv
Joined: 27 Aug 2007 Posts: 628 Location: Australia
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Link Posted: Sun Jul 17, 2016 8:41 pm Post subject: |
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Can you see the same problem on the Barco 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 8:54 pm Post subject: |
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Calman has some smooth gradients in its collection of test patterns.
How do THOSE look?
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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: Sun Jul 17, 2016 10:27 pm Post subject: |
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gregstv wrote: | Can you see the same problem on the Barco step pattern? |
That pattern looked near perfect so no problem there, but hopefully your probe was on the final (G1 or cathode) connection to the CRT. If so, that looks right.
Because we're not doing bandwidth critical testing, there's no need for FET probes and special techniques to do a good capture. But may want to make sure your probe trim pot is adjusted if it has one.
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gregstv
Joined: 27 Aug 2007 Posts: 628 Location: Australia
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Link Posted: Mon Jul 18, 2016 12:26 am Post subject: |
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Probe was on test point M4 on the neck board. This is at the tube. The probe is 200mhz standard type with x1 or x10 switch.
I have been doing lots of mods to reduce noise. I have been comparing noise by looking into the lens. I need to learn more about what I am looking at on the oscilloscope when it comes to high bandwidth video.
Signal chain is as follows,
Panasonic blu ray player, $25 splitter, DVDO VP50, analog out to port 3 in. Modded port 3 card, modded switcher, modded driver and neck board.
Modded means component change our parts added. Nothing to the level of Mikes talent. I might get there one day but have a lot to learn. This stuff is black magic.
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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: Mon Jul 18, 2016 1:32 am Post subject: |
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gregstv wrote: | Probe was on test point M4 on the neck board. This is at the tube. The probe is 200mhz standard type with x1 or x10 switch.
I have been doing lots of mods to reduce noise. I have been comparing noise by looking into the lens. I need to learn more about what I am looking at on the oscilloscope when it comes to high bandwidth video.
Signal chain is as follows,
Panasonic blu ray player, $25 splitter, DVDO VP50, analog out to port 3 in. Modded port 3 card, modded switcher, modded driver and neck board.
Modded means component change our parts added. Nothing to the level of Mikes talent. I might get there one day but have a lot to learn. This stuff is black magic. |
That pattern you showed was good, considering all you have in your video chain. The more of anything in the video chain, it will take away your ability to experience the HD depth and transparency.
Also, and as I mentioned previously in this thread, it's best to do the final using an analog scope. It's more revealing when looking for noise
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gregstv
Joined: 27 Aug 2007 Posts: 628 Location: Australia
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Link Posted: Mon Jul 18, 2016 2:29 am Post subject: |
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Thanks Mike, by analog scope you mean CRT? Both mine are old LCD. The 60mhz Tektronix is 20+ years old.
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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: Mon Jul 18, 2016 2:53 am Post subject: |
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gregstv wrote: | Thanks Mike, by analog scope you mean CRT? Both mine are old LCD. The 60mhz Tektronix is 20+ years old. |
That should be fine though
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