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DLP Pincushion effect

1006 Views 7 Replies 5 Participants Last post by  c1courtney
I have a Samsung HLN 50" DLP and I have recently noticed a pincushion effecit (a bowing in of the center of the vertical edge of the picture on 4:3 mode). It measures approx 1/2" difference between the center of the picture and edges. Several questions arise:

-Is this something endemic to all DLP RPTV or more specifically the Samsung lines?

-Will the effect worsen over time?

-Are any adjustments possible the minimize the effect?

Any advice would be helpful. I am currently discussing the problem with Samsung.
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Most microdisplays are guilty of having similar symptoms. Some worse than others. Unless you can do any specific geometry corrections within the service menu, I would say that there isn't much to do but get another television and see if it exhibits similar issues.

I currently have a LCD RP that is also guilty of pincushioning, alas, it is not that noticable though. I can check the amount of pincushioning I am getting if you like.
I believe all Samsung tv's do this in 4:3 mode. I don't know about other DLP's. It has something to do with the short distance from the light engine to the screen that causes the bowing. It won't get any worse, but it also won't get any better.
All Microdisplays do this to some degree or another.

Do to fixed optics you're going to have some pincushioning (either at the edges of the 16:9 or edges of 4:3 image when displayed.) This is fixed (because the optics are fixed) and there aren't any adjustments you can make for it. This is the nature of optical lenses.

RP CRTs in the 16:9 format have this as well, you may be able to adjust some of it out because w/ a CRT you can change the sweeping widths across the screen - this is not a change in the optics but a change the sweep electron beam of CRT.

My advice is to sit back and relax, stop trying to scrutinize the set and you'll be a happier person for it.

The fact is you've been living with Pincushioning all your life w/ CRT sets and haven't noticed it because of the overscan and curvature of the surface and edges. It wasn't really until computer monitors were created that people tried to do something about it (because you don't want overscan on computer monitors and you want everything lined up all nice and pretty.)
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While it seems to be that case that all displays have this to one degree or another, I am curious if some sets are worse than others within the same model line or with the newer HLP sets.

A colleague of mine with a HLN61 series actually had about 1/2" pincushion. The Samsung service center thought this was excessive and landed up taking apart his tv twice to try and correct it.
I think .5" might be too much and would call Samsung. Our HLP5063 probably has about .25" which doesn't bother me.
I have an LCD RP and I also notice a slight pincushion effect, however, my buddy has the 42" version(same model) and his is alot more pronounced. Either way, I think you should learn to live with it, as I could imagine numerous techs showing up to attempt to fix the problem, and not doing anything but making things worse.
How is everybody measuring pincushioning?

Is it the difference across the entire width at the center verses the top/bottom. (i.e. 40" across at top of 4:3 and 39.5" across the middle = 1/2" pincushioning.)

Or is it the distance in from what would be a vertical line at the side edge (which should be 1/2 the previous - the above would be 1/4" in from the vertical line.)
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