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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Fri Sep 17, 2010 1:59 pm Post subject: 720p seen in 4:3 |
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I suspect this will be a very newbie question, but I only own a crt pj for less than a year. -and this time went with error finding in the PJ...
The problem: If I set the desktop resolution to 1280x720 the pj projects it as a 4:3 format picture. What to do?
My vga card now is a radeon 9000, I have powerstrip too (V 3.76) I tried with custom timings, but none of that worked (in some timings the picture didn't change, in others the picture tumbled and can't sync) The pj is a NEC PG xtra if it is matters.
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AnalogRocks
Forum Moderator
Joined: 08 Mar 2006
Posts: 26706
Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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| Posted: Fri Sep 17, 2010 3:01 pm Post subject: |
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You need to send 1280x720 to the projector then use the controls on the projector to decrease the vertical height until you get 16:9
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Fri Sep 17, 2010 3:28 pm Post subject: |
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Oh it's really simple 
I taught this too, but I'm affraid to set the controls to that extreme positions (V size must be '-100%' H size must be '+lot%') I'm affraided to over stress th pj, but if there is no other way...
Thanks!
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Sun Sep 19, 2010 11:35 am Post subject: |
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I found out another solution which may stress less the electronics: to send 1280x1024 to pj, and blanking out the bands from up and down -but in this way higher bandwidth needed.
But I have another question.
I've played around the interlaced modes, but these didn't work me...
If I check in the powerstrip the 'interlaced' button (no matter in which resolution) I can't get normal picture. It seems to be sync because the picture not rolling but it tumbles down. How to resolve this?
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Wed Sep 22, 2010 7:15 am Post subject: |
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1280x1024 will stress projector more since it's higher resolution, even borders blanked. Deflection circuit still draw whole resolution, but doesn't send it to tubes.
Decreasing 1280x720 to 16:9 doesn't stress projector any more than using it as 4:3, those are just numbers in menu.
With my radeon it's needed to set interlaced resolution first from radeon drivers, then timings can be tweaked from Powerstrip.
http://www.curtpalme.com/forum/viewtopic.php?p=229074#229074
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Wed Sep 22, 2010 1:26 pm Post subject: |
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Thanks! I taught to blank the picture because if I set the picture sizes to get 16:9 in 1280x720 the heatsink of the deflection board run hot immediately, but in 1280x1024 with 'natural' picture sizes, not. But you are right too. Now I see why it is recommended to add a fan to the deflection board on a NEC PG
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Wed Sep 22, 2010 6:23 pm Post subject: |
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| gjaky wrote: | | Thanks! I taught to blank the picture because if I set the picture sizes to get 16:9 in 1280x720 the heatsink of the deflection board run hot immediately, but in 1280x1024 with 'natural' picture sizes, not. But you are right too. Now I see why it is recommended to add a fan to the deflection board on a NEC PG |
That's weird and makes no sense unless there is great difference in vertical refreshrate or porch settings between those two resolution.
Check horizontal scan rate (kHz) from Powerstrip for those resolutions. If 720p really have higher value, you can compare horizontal porch and vertical refresh values from Powerstrip.
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gjaky
Joined: 05 Jun 2010
Posts: 2802
Location: Budapest, Hungary
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| Posted: Wed Sep 22, 2010 7:36 pm Post subject: |
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Now I tested again in longer period, and you're right. In 720p the PJ works fine and mild. The interlaced modes are also should work, because 1080i@30 is working, so the others should too, I will be playing around this...
Thanks for helping!
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