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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Thu Jan 01, 2015 8:16 pm Post subject: little banding I need to fix on the far left side of Marquee |
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Hi,
I know I saw a fix for this before, but I can't remember the steps. I have some verticle banding on the far left side of my Marquee. I know there is a tsb for foldback issue on the lfet side, but this does not look like foldback.
Thanks
God bless...
Mark
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Fri Jan 02, 2015 12:11 am Post subject: |
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| Nashou66 wrote: | It is not banding, that is ringing. The only way to really eliminate it is to use a VP or HTPC where you can alter the timings. Adding a large back porch to move the ringing off the tube face is the only real solution.
Athanasios |
Bummer, Thanks for the info though...
One interesting thing, it seems to have changed with that latest set of mods I did on the VIM. WHat signal/chip is ringing?
I bet there has to be a way to stop it without a VP or HTPC...
God bless...
Mark
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stridsvognen
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| Posted: Fri Jan 02, 2015 12:14 am Post subject: |
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It has nothing to do with the VIM. you would need to take a look on the HDM, and let us know when you fix it.. 
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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Fri Jan 02, 2015 12:19 am Post subject: |
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| stridsvognen wrote: | | It has nothing to do with the VIM. you would need to take a look on the HDM, and let us know when you fix it.. |
I'm sure you're right but I've got to say that my latest batch of VIM mods definitely changed it even if the main source is from the HDM the VIM plays in somehow.
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stridsvognen
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| Posted: Fri Jan 02, 2015 12:26 am Post subject: |
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| htguy1 wrote: | | stridsvognen wrote: | | It has nothing to do with the VIM. you would need to take a look on the HDM, and let us know when you fix it.. |
I'm sure you're right but I've got to say that my latest batch of VIM mods definitely changed it even if the main source is from the HDM the VIM plays in somehow. |
Can you shoot a few screenshots of a full white screen showing the difference.?
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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Fri Jan 02, 2015 12:56 am Post subject: |
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[/quote]
Can you shoot a few screenshots of a full white screen showing the difference.?[/quote]
I can try but my stinks at screen shots...
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stridsvognen
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| Posted: Fri Jan 02, 2015 1:09 am Post subject: |
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Can you shoot a few screenshots of a full white screen showing the difference.?[/quote]
I can try but my stinks at screen shots...[/quote]
Most of us do.. So your not alone.
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jbmeyer13
Joined: 03 Dec 2010
Posts: 1135
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| Posted: Fri Jan 02, 2015 4:28 am Post subject: |
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| stridsvognen wrote: | | It has nothing to do with the VIM. you would need to take a look on the HDM, and let us know when you fix it.. |
Kurt is 100% correct; the vim has nothing to do with it. Supposedly, there was an HDM produced for Boeing simulators that doesn't ring but there's no part # confirmation.
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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Tue Jan 06, 2015 2:58 am Post subject: |
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Hi,
So my brother works for Boeing, but sadly for us he works in the wind tunnel testing division, so I don't know if he can help us track one of those Marquee's down, but just for the fun of it I asked him if he could ask around...
You guys were right, contrary to my recollection, the stock o2p VIM has just about the same ringing on the left side of the pic as the modified one.
So does anyone have any ideas on what part of the HDM is causing the ringing?
Thanks
God bless...
Mark
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Posted: Tue Jan 06, 2015 4:55 am Post subject: |
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| htguy1 wrote: | Hi,
So my brother works for Boeing, but sadly for us he works in the wind tunnel testing division, so I don't know if he can help us track one of those Marquee's down, but just for the fun of it I asked him if he could ask around...
You guys were right, contrary to my recollection, the stock o2p VIM has just about the same ringing on the left side of the pic as the modified one.
So does anyone have any ideas on what part of the HDM is causing the ringing?
Thanks
God bless...
Mark |
No part in particular , just the design. To eliminate ringing at high frequencies Electrohme
would have had to design a HDM that could be placed right on top of each deflection coil.
It has to do with the inductance of the entire circuit.
What ringing is as I understand it, the electron beam draws the image from left to right
and as you increase the frequency it moves extremely fast. As it begins the
next line after being blanked it does not have time to settle down to a stable
beam as it begins the new line. So one way to allow it to have more time is to increase the back porch
pixels. That is why we say you need a VP or HTPC to address this issue. All CRT's suffer from this.
You could also try to set the raster off to one side more to increase area of the phosphor
the beam begins to draw the image.
Athanasios
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