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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Wed Oct 24, 2012 3:00 am Post subject: Hey Scott! Remember the Medium Retrace mod? |
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Guys
This would give more useful width in what is now short retrace on a Marquee. If my computer hadn't blown up two years ago I'd post it myself......
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Wed Oct 24, 2012 7:34 pm Post subject: |
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this is something that's done to the HDM?
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Wed Oct 24, 2012 7:43 pm Post subject: |
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Yes
Providing Scott gets back to us 
I had the info in an e.mail and it was lost in a crash.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Thu Oct 25, 2012 7:37 pm Post subject: |
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Guys
I was hoping Scott would visit us here, he has the info for this.
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htguy1
Joined: 30 Jul 2008
Posts: 99
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| Posted: Fri Oct 26, 2012 4:31 am Post subject: |
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Calling Scott! Come back and help us!
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Fri Oct 26, 2012 1:26 pm Post subject: |
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The retrace caps (C4, 5, 6, 7, 10, and 11) values can be increased to increase the flyback time. This will decrease the "write" time which makes the active video time cover more of the raster. Probably the best thing to do is just parallel the caps that are already there with 1nF 1000V polypropylene parts. If the raster "wraps" around the caps are too big if still too much unused raster add slightly higher value or more of the 1nF parts. Increasing the cap value decreases the flyback voltage so there is little danger in properly adding caps of reasonable value. I have included a Mathcad file that calculates the the voltages and cap values.
Good Luck,
Scott
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Fri Oct 26, 2012 2:04 pm Post subject: |
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So Scott
This affects both short and long retrace?
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Fri Oct 26, 2012 3:06 pm Post subject: |
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Both long and short will increase but the long will increase less than short.
Scott
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"Were we directed from Washington when to sow and when to reap, we would soon want bread."
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Fri Oct 26, 2012 4:22 pm Post subject: |
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yes it is.
on long retrace i think an extra cap is switched on with a relay an put in parallel with the caps across the fets.
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marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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Tim in Phoenix
Joined: 21 Oct 2006
Posts: 4409
Location: Phoenix
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| Posted: Fri Oct 26, 2012 4:59 pm Post subject: |
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Guys
I have some caps ordered for testing, let me get back to you in a week or so........
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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tse
Joined: 03 May 2006
Posts: 1014
Location: Sweatbucket, Fl.
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| Posted: Fri Oct 26, 2012 5:15 pm Post subject: |
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| Nashou66 wrote: | Thats looks like the formula in the Marquee thread regarding those Cree fets. Is it the same?
Athanasios |
Yep.
Scott
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"Were we directed from Washington when to sow and when to reap, we would soon want bread."
Thomas Jefferson
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thewolfman
Joined: 28 Mar 2011
Posts: 1311
Location: Sweden
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| Posted: Fri Oct 26, 2012 9:43 pm Post subject: |
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deleted
Last edited by thewolfman on Sun Oct 28, 2012 5:04 pm; edited 1 time in total
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dturco
Joined: 06 Feb 2009
Posts: 3778
Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Fri Oct 26, 2012 9:59 pm Post subject: |
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| tse wrote: | The retrace caps (C4, 5, 6, 7, 10, and 11) values can be increased to increase the flyback time. This will decrease the "write" time which makes the active video time cover more of the raster. Probably the best thing to do is just parallel the caps that are already there with 1nF 1000V polypropylene parts. If the raster "wraps" around the caps are too big if still too much unused raster add slightly higher value or more of the 1nF parts. Increasing the cap value decreases the flyback voltage so there is little danger in properly adding caps of reasonable value. I have included a Mathcad file that calculates the the voltages and cap values.
Good Luck,
Scott |
Scott, in about two years I'll be able to do this. But right now, it makes no sense at all. How can a voltage or re-trace length be 10 to sixth power negative? Or is that just to show how small it is in length in relation to the fictional start point of 1 meter?
You don't have to answer, I just wondering out loud, as I have yet to tackle my math requirements starting at Algebra...
101 
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Fri Oct 26, 2012 10:34 pm Post subject: |
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| dturco wrote: | | tse wrote: | The retrace caps (C4, 5, 6, 7, 10, and 11) values can be increased to increase the flyback time. This will decrease the "write" time which makes the active video time cover more of the raster. Probably the best thing to do is just parallel the caps that are already there with 1nF 1000V polypropylene parts. If the raster "wraps" around the caps are too big if still too much unused raster add slightly higher value or more of the 1nF parts. Increasing the cap value decreases the flyback voltage so there is little danger in properly adding caps of reasonable value. I have included a Mathcad file that calculates the the voltages and cap values.
Good Luck,
Scott |
Scott, in about two years I'll be able to do this. But right now, it makes no sense at all. How can a voltage or re-trace length be 10 to sixth power negative? Or is that just to show how small it is in length in relation to the fictional start point of 1 meter?
You don't have to answer, I just wondering out loud, as I have yet to tackle my math requirements starting at Algebra...
101 |
When the power is negative it goes fractional. 10 to the 6th power negative would be 1/1000000 or 0.000001
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dturco
Joined: 06 Feb 2009
Posts: 3778
Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Fri Oct 26, 2012 11:23 pm Post subject: |
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| Quote: | | When the power is negative it goes fractional. 10 to the 6th power negative would be 1/1000000 or 0.000001 |
I get its a fraction of something, just like when I'm doing microscope work the object is really small. But the size is always related to the starting point of 1 meter.
Down 10 to the 6 negative as 6um, as a measurement or 1 millionth of a meter. I get that because I can see it in the scope but as pure math... I freeze.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Fri Oct 26, 2012 11:31 pm Post subject: |
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It's fractional to where it is being applied. If it's time it is fraction of a second. If it's voltage it's fraction of a volt. If it's cap value it's fraction of a farad. If it's resistance it is a fraction of an ohm...... shall I continue?
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dturco
Joined: 06 Feb 2009
Posts: 3778
Location: Eastern Shore Maryland
TV/Projector: Runco DLP VX-3000i Marquee 9500 parts doner
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| Posted: Fri Oct 26, 2012 11:35 pm Post subject: |
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| macgyver655 wrote: | | It's fractional to where it is being applied. If it's time it is fraction of a second. If it's voltage it's fraction of a volt. If it's cap value it's fraction of a farad. If it's resistance it is a fraction of an ohm...... shall I continue? |
Ahhh, the starting point is known; because of the application. Got it.
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