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Blue Pixels on a new VT540  

post #1 of 18
Thread Starter 
I'm now the proud owner of a new NEC VT540 projector, driven by a home-built HTPC. Wow, what an amazing experience to watch 8' wide films and surf and play games on a true "Big Screen"! My beef with this particular unit is some cyan colored pixels in some bad spots. There's at least two, maybe three that I can see on any viwed material because they're near the center of the display. There's at least five other ones, but they're around the perimeter of the picture and don't get seen during movies and aren't really noticed for other computer activities.

I know an LCD panel has a million or so of these pixels, so expecting them all to be funtioning is probably over-optomistic. My laptop display gets blue pixels sometimes, but I can usually get them to turn back on with a gentle nudge from a pencil eraser. I can't really try this technique with the projector's panel.

My questions are:

Are these pixels "stuck" or "dead", and will they be this way forever?

Do I have a reasonable gripe about my unit, or is a few bad pixels acceptable for the industry.

Has anyone had any luck with a manufacturer giving them a replacement unit for a few stuck pixels?

Should I send it back where I bought it (they have a 30 day "100% satisfaction guarantee") or deal with NEC's InstaCare?

What's the best color image to project so I can start counting all of these pesky pixels before I get on the horn with warranty service... all white screen, all black, grey, etc.?

I'm still pleased as punch with my new purchase, even if I have to live with a few bad pixels. No one seems to notice them til I point them out... they're just sitting there with mouth agape. What an amazing AND afordable Big Screen I have!

Thanks all,
Brian
post #2 of 18
I have a VT540 also. The original unit had two always on blue pixels. After speaking with tech support, they agreed to swap it out and sent me a new unit which they previewed first. This unit has a couple of yellow pixels in the periphery which are not bothersome.
post #3 of 18
If I had two or more dead pixels near the center of the screen, I'd request that my dealer send me another one!

I agree, we can't expect LCD panels to always be 100% perfect. However, I feel we're entitled to a considerable level of satisfaction when it comes to making such sigificant purchases.

On the other hand, my experience with the LT155 was the same as Andy's. The model I had on loan for a few days did not have a single bad pixel.

Frank
post #4 of 18
Just an FYI. The NEC VT540/440 was designed and built to be an inexpensive, stripped down, low end projector for the education market and cost conscious buyers. It was never meant to be the best of the best. That's why you can find new XGA units for $3k or under.

Mike
post #5 of 18
Thread Starter 
Thanks all, I will get on the horn with NEC and tell them I'm driving a HT with the projector and see if they can weed out a center dead-pixel-free unit. I hear their customer support is really exceptional.

I'm sure the QC of the manuf. process is why we can find quite a few refurb. units out there AND why they're so affordable to begin with. The LT155 was really out of my budget, so I'll take a few bumps in the road for $1k less. I wonder if NEC is disappointed as to just how well these affordable projectors do for HT applications, since now they have to support a much more finicky audience at a price point/ profit margin that was never intended to offer such support. Maybe they'll "dumb down" their next "entry-level" units to avoid this problem.

Honestly, I could spend three times the money for a "best of the best" projector and still have had other disappointments about my purchase, since any particular model/ technology is going to have its pros and cons.

Thanks again,
Brian
post #6 of 18
Brian,

I've had my VT540 for about two weeks now, and don't see any "dead" pixels. Not to say that they aren't there, but on normal program material they don't exist. I see that you are in the Longmont area. I set up my projector for forum member James (in Boulder) and there were no stuck or always on pixels. I have however put the picture in "mute" mode and walked up to about three feet from the screen, and I do notice some of the spots that "tk" mentioned above, but they don't appear to be pixels. Due to the fact that they are too small and rounded in shape. Eitherway they never show up with ANY program material!! Once I get the theater finished, you are more then welcome to stop by to check it out. That is if you can wait that long. I'd personally call up NEC to see what the policy is.

You can email me to set up a time to stop by if you'd like.
Good luck,
Mike

------------------
Let's go out to the lobby.
Let's go out to the lobby.
To have ourselves a snack!
Michaeldare@earthlink.net
post #7 of 18
From what I hear dead pixels free LCD projectors are rare to find and count yourself lucky if you have one. I have just opened my brand new Sony VW10HT and found one dead pixel (blue) to the top right corner of the image. I have been told that you could end up receiving a unit that has more dead pixels then what you have already therefore I am going to stay with the unit, as it seems to work fine apart from this minor problem.

I must stress that having pixels out in the center of the screen would normally cause the unit to fail its factory inspection, which would imply that you should return it and request a replacement. Having pixels out in other areas other then the center would not normally prompt replacement from the manufacture.
post #8 of 18
My friend was just about ready to buy a VT540, but he went through 10 (Ten!) of them and none of them were dead-pixel free.

He later found out from NEC that this is relatively common for the VT540, and that the LT155 was made with a greatly improved manufacturing process. As a result, your odds are much better of getting a good LT155 than a good VT540.

Andy K.
post #9 of 18
Thread Starter 
Well, last night during a screening of "The Mummy" I paused the playback and took a close look at the screen, then blanked the picture to its default blue and black screens to check for pixel problems. Like "tk" mentioned, the spots I'm seeing aren't quite full pixels and some are the cyan color, others are like green streaks, very ill defined. Even a weird red streak on one. Right next to the screen I can clearly make out individual pixels (alas, with LCDs, pixels can be evident half the room away!) and none of the center "specks" are full pixel size nor are they a distinct square shape. There are two full-size, full cyan square "dead" pixels in the very bottom left corner edges, but I'm not concerned about these because they're even beyond the typical scan of 4:3 material.

I'm wondering if it's dust I'm seeing, but I would think dust in front of the light path would block light and render itself as dark grey or black on the screen. Do LCD projectors truly have 3 panels, one for each primary color? Do these then get combined on a different panel before projection? This might explain the different colors I'm seeing, depending on which color panel has the defect/ dust.

Living at higher altitudes than most other places might explain why some of my optics (cameras, scanners, binoculars, etc.) manuf. in lower elevations can get dust "sucked" up into them when shipped here. I wonder if this is what's happened to my projector and maybe there's a way to get the crud out of the light path w/o voiding my warranty.

Any more light shed on this problem http://www.avsforum.com/ubb/wink.gif would be greatly appreciated,
Brian
post #10 of 18
I have seen all of the above mentioned with the VT540. My friend who purchased one has also.

In my case, the first unit I had was horrible. It had 30+ of the off colored 'specs' all over the panel. I could see at least 8 of these 'specs' from my viewing distance. I called NEC and they were GREAT! I received my second unit overnight and this projector is much better. There are no dead pixels/dust afflicted pixels that appear in the 16:9 portion of the panel. I can barely see one or two of the off colored pixels from 15 feet away (my viewing distance). This will be taken care of by my masking material. If I am very close to the screen, I can count about 10 of these 'specs'.

My friend also went through the InstaCare exchange (3 times) and ended up with a 0 hour unit that was inspected by their support people (there are a couple tiny faint off color spec on it, none that can be seen from viewing distance).

Overall, I am happy with NEC's attemp to remedy my problems. I doubt anyone will find a perfect VT540 panel, but your chances to obtain a viewable panel are good. At least their support makes an attempt, unlike the Sony support!

-Mike
post #11 of 18
The VT540/440 was definitely designed to be a low-end projector. That's a fact. The easiest way to understand it is to think of the projector from a corporate stand point. Low lumens to weight ratio, no monitor loop through and no remote computer mouse control(available as an optional accessory).

In regard to one Mfg's low-end projector having more defects than another, it is most likely attributed to the cleanliness of the facility it was assembled in.

The "small dead pixels" that many are referring to are in fact dust particles on the panels. Those who have had the displeasure of seeing a true dead pixel know there is a huge difference between a dead pixel and dust. Most dust particles are small enough that they can't be seen when you're displaying a video source, but they will always be visible if you set the projector to a blank black screen and look closely. If you have a blank blue background showing, you will most likely never see a dust spot, but you will clearly see a dead pixel. The confusion over dust vs dead pixels seems to be the biggest issue when it comes to LCD panels.

Just to reiterate, dust on an LCD panel does not mean the panel is defective. It simply means that at some point in the assembly process, or through normal air circulation, dust has made it's way onto the panels. For this very reason, many LCD users on this forum use cans of compressed air to blow dust off the panels to alleviate the problem.

Hope this helps.

Mike
post #12 of 18
I have the same problem with My sharpvision, and no, they are not dead pixels, as you have determined. The dust, however, my not be on the panel directly. THerefore, what you might try to do is change the focus, then you will be able to see the defined edges of the dust particles. I did this once, and found a piece of HAIR!!! causing a shadow, which disppeared when I refocused the image. Try it out.

Funny thing is (knock on wood!!!) I have no dead pixels with my 4 year old projector. Sure, its 640x480, but still lucky. I got LOTS of dust though.

------------------
David Mendicino
Sharp xv-s55u (Don't laugh) :)
post #13 of 18
Thread Starter 
Yeah, if I look inside the lens obliquely while it's on, I see ALL kinds of dust on what appears to be a mirror. The unit has filters on it that are supposed to be cleaned every hundred hours, but my unit has less than 50 on it, so I think it came to me that way.

Is there a way to get inside the panel-housing and suck or blow some of that crud away?

I think my pixel problems will largely go away with a cleaner mirror and panels, not to mention I'll probably have more apparent picture sharpness than before.

Any ideas out there?

Thanks a bunch,
Brian

[This message has been edited by archtech (edited 04-19-2001).]
post #14 of 18
As far as using compressed air to blow out the dust ... is that a safe approach? I would really be interested in trying that out if it was easily accessable (where do you 'blow' from? take the lamp out? from one of the removable side filters?).

Any direction would be appreciated!

-Mike
post #15 of 18
Wanted to Bump this thread up ...

Still looking for info from anyone who has attempted to blow the dust off the LCD panels on a VT540/440. Is this a simple job, or is it better left to an projector technician? What is the easiest access to the panels?

-Mike
post #16 of 18
Thread Starter 
Bump bump...

Spoon Man, make that two us, looking for advice on "dusting off the panel". I would think this would be a maintenance issue and NEC wouldn't want to swap out units on a regular basis just for some dust problems.

Maybe I'll try to email their tech. support. They were real responsive sending me an *.inf file for my VT540. I can't believe this is an isolated problem. Maybe in our cases the altitude "sucks in" the dust during shipment, I dunno.

Any help out there?

Brian
post #17 of 18
Is it true that only VT540 is showing all these problems and other projectors doesn't?
Or are we just looking our units too hard?
post #18 of 18
Thread Starter 
TK,

As for me, I only looked REAL hard after noticing a bad pixel on the edge of my screen and then I saw these defects in the center on close inspection. From my normal seating position I cannot see the dust defects.

I'm wondering if our VT540s and other projectors have sealed panel area(s) and the dust is a result of poor manuf. conditions OR a fairly typical maintenance issue that's a byproduct of the fan sucking in cooling air for the bulb and dust getting past the filters. There's a reason why they put filters on the fan intakes I'm assuming, not just to protect the bulb from dust, grit, bugs, etc.

I just don't want to get crazy with a can of compressed air until I know whether on not it's a good idea to blow off the panels. And if it's a sealed area around the panels, I wouldn't be able to blow them off anyway.

Anybody out there know anything about this? In the meantime, I'll continue to enjoy my projector and tell myself "dust happens".

Brian
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