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Author Topic: NEC NP600 PROJECTORS - HOT SPOTS  (Read 3071 times)

James A. Griffin

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NEC NP600 PROJECTORS - HOT SPOTS
« on: September 03, 2012, 08:06:28 pm »

I have two of these, 1 with about 100 hours on bulb, 1 brand new out of the box.

Set them up today for a corporate show I'm doing tomorrow night.      Set up is Computer >> Ocean Matrix 1 x 4 DA >> two projectors.

1 of them has a hot spot bottom right corner, other has a hot spot bottom left corner.       Any clue why?    Just cheap projectors?

Also, the newer projector is noticiably brighter than other. Thinking that shouldbn't be a factor with only 100 hours on the bulb (100 hours on the unit too).

Both projectors are below the screens, pointed up.
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Brad Weber

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Re: NEC NP600 PROJECTORS - HOT SPOTS
« Reply #1 on: September 04, 2012, 05:27:51 am »

Both projectors are below the screens, pointed up.
Are these the NP600 or the NP600S?  If they are the NP600 then the projectors should apparently be located a specific distance above the bottom of the image for desktop configurations and below the top of the image for ceiling mount with that distance depending on the overall image size, according to the manual 9" for a 100" diagonal image, 14" for a 150 diagonal image and 19" for a 200" diagonal image.  With no vertical lens shift, you may be able to correct for keystoning from the projector being lower but not necessarily for other aberrations caused by the projectors not being at the desired vertical location relative to the projected image.  And similar for the horizontal position, with no horizontal lens shift or keystone correction the lens should be at the center of the image.  So it may not be a factor of "cheap projectors" as much as projectors that do not have the functionality that is apparently appropriate for how they are being used.  You might want to try it with the projectors at the recommended locations and see if that helps, that might at least confirm or disprove that being the cause.
 
Are the screens a matte white true projection material, a higher gain projection material, a painted wall or some other surface?  The projector being in a less than optimal location and possibly at the short end of its throw could cause some hot spotting but a high gain screen, painted wall surface, etc. could make any hot spotting even more apparent.
 
As far as lamp life and brightness, the lamp may have 100 hours of use but how many times has it been powered on and off and has it always been properly cooled down after use?  Although they may both represent 100 total hours of use there can be a big difference between 12 or 13 all day uses with proper shut down and 100 or 200 hour or less uses with some uses involving powering off the projector before being properly cycled.
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James A. Griffin

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Re: NEC NP600 PROJECTORS - HOT SPOTS
« Reply #2 on: September 04, 2012, 06:49:15 am »

Thanks for reply, Brad

They are NP600, projecting from rear on the basic DaLite rear surface   I think it's called DaMat but I could be wrong about that.

I think you might be onto something with the throw length and projector height. We didn't have enough room behind screen for optimal projector distance so I put the zoom control to max to fill up the screen.    Perhaps backing off of that might give a smaller picture with better quality?
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James A. Griffin

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Re: NEC NP600 PROJECTORS - HOT SPOTS
« Reply #3 on: September 04, 2012, 12:45:29 pm »

After looking at it again with fresh eyes this morning, I see that the hot spot positions change when I move around the room, which tells me that I'm just seeing the projector through the screen.   It has nothing to do with the projectors themselves...

I'm still a bit curious about the older projector looking a little duller than the other, even though it only has 100 hours.    Could it be a difference in the two screens?   Maybe I swap projectors to test that idea.
« Last Edit: September 04, 2012, 12:48:21 pm by James A. Griffin »
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Brad Weber

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Re: NEC NP600 PROJECTORS - HOT SPOTS
« Reply #4 on: September 05, 2012, 05:54:01 am »

After looking at it again with fresh eyes this morning, I see that the hot spot positions change when I move around the room, which tells me that I'm just seeing the projector through the screen.   It has nothing to do with the projectors themselves...
That makes sense, if it is a flexible rear projection surface the material may be Da-Tex and it has a pretty narrow viewing angle, Da-Lite offers an Ultra Wide Angle flexible rear screen material that has a wider viewing angle and is less likley to hot spot but is just 0.65 gain versus the 1.3 gain of the Da-Tex, so you trade off image brightness for the viewing angle.

I'm still a bit curious about the older projector looking a little duller than the other, even though it only has 100 hours.    Could it be a difference in the two screens?   Maybe I swap projectors to test that idea.
It could be the screen, the projectors, environmental conditions such as the ambient light on the screens or a combination of those.  It could also be related to the viewing angles, Da-Tex has a 30 degree viewing angle and since many viewers will have different relationships to the two screens the difference in off axis projector output and screen gain could result in differences between the two images.
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ProSoundWeb Community

Re: NEC NP600 PROJECTORS - HOT SPOTS
« Reply #4 on: September 05, 2012, 05:54:01 am »


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