Black and White "dots" all over my projector screen. What causes it? - AVS | Home Theater Discussions And Reviews
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post #1 of 24 Old 11-27-2012, 01:54 PM - Thread Starter
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I got a cheap DLP projector from Dell, since I was on a budget and I just needed one that I could play xbox on. I'm pretty happy with it, since it does what I needed it to do, until this problem started happening. At first, a few white dots started showing up here and there. It's annoying when you're watching a movie, but not so much when you're playing a video game, so I barely noticed. However, these little white dots started to multiply all over the screen, and it became *extremely* annoying. Not only that, but these small black dots started showing up everywhere as well. The screen is not usable now. I can't even read text on the menus.

I probably should have called Dell a long time ago, but I've been busy with school and work, etc. I finally called them today, and they are replacing it. My question now is: what could cause this problem? Is it that it's a cheap projector? Could I have done something wrong to cause the issue? Was it just a defective unit? The reason I ask is because I want to know how this can be avoided with the new projector they are sending.

Has anyone else experienced this problem? I should mention that the model is Dell M410HD. Here is what the problem looks like:

A really bad projector image

BTW, this picture is pretty low quality, and if you guys need some more detailed ones, I can snap a few tonight. Basically, the white dots seem to be present more on the left side of the screen. The black dots are all over the place, and will sometimes spell "DELL" and "DLP" right in the center of the screen. This is normally what you see when you first turn on the projector, and also when you turn off something connected to the projector (like an xbox). Thanks for your help.
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post #2 of 24 Old 11-27-2012, 03:01 PM
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Heat.

The lamps throw off tons of heat, it is a few hundred watt bulb in a tiny box. Over time and heat cycles this can kill a projector in unexpected way. The next one you get might last 1000x longer it is a bit of a dice roll. In your case is seems bits were getting stuck on/off. Glad to hear Dell is replacing it for you.
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post #3 of 24 Old 11-27-2012, 04:21 PM
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This is a guess but the same thing has happened to two samsung rear screen DLPs TVis I had. it was the DLP chip. common problem with some models DLPchips.

http://forums.cnet.com/7723-13973_102-548571/white-black-spots-on-samsung-dlp-tv-model-h-lt6176sx/

http://www.youtube.com/watch?v=JrcgVDbe9_w


Google ,,, DLP chip white dots

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post #4 of 24 Old 12-03-2012, 02:41 PM
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First thing to do is eliminate the cable as a potential cause. Try a different cable type (component, rgb, composite, s-video) to see if the problem goes away. Run a short cable straight from the source to the projector without anything in the way (switchers, receivers etc). Does your projector display a splash-screen that does not require an external source and if so, is the problem there as well?
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post #5 of 24 Old 02-26-2013, 09:11 AM
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Dell.jpg 65k .jpg file There are THOUSANDS of DLP Projection TV's and Projectors with the same problem. Dell is not the problem, the problem is the fact that they used Texas Instruments (TI) DLP DMD device - they are failing with the white dot syndrome in DROVES, I have numerous projectors all manufactured within the past 4 years with the same problem, they are Mitsubishi's Viewsonics, NEC, InFocus, Dell, and others - I do not know why TI has not fixed the manufacturing problems. THE DMD's are fine up until about 4 years ago. Older projectors do not have the problem. IN MY OPINION, Someone needs to start a CLASS action against TI. They have to know there has been an ongoing problem with all their DMD’s and they are not OWNING THE PROBLEM.
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post #6 of 24 Old 02-26-2013, 11:13 AM
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Agreed. Especially when they touted that the DMD would easily last 10years! My fear is that the replacements will go bad in 4 years too. I've seen no indication that the replacement parts are different, but then nobody has verified if new replacements have a different part number.

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post #7 of 24 Old 03-01-2013, 01:57 PM
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Vincent Dunn
THANK YOU SO MUCH,
Apart from 1000 different opinions (most common dust or stuck micro mirrors like in my case),

ONLY You, given very precise and clear explanation!!

thanks to TI -my LAMP going to OUTLIVE the CHIP 2 TIMES Dell Lamp have approx. 3000hrs. live

AND MINE IS NOT EVEN 1600hrs. old frown.gif

And more.. and more.. white spots....

I have a guess Your work includes explaining that, to more and more unhappy customers within last few years, and it s clear You know those facts from first hand

THANKS

i will buy next gen. of display not sooner than they will offer direct implant to the brain thought..
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post #8 of 24 Old 04-13-2014, 12:26 PM
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So you're saying that dust is not the problem at all?

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post #9 of 24 Old 04-13-2014, 02:18 PM
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So you're saying that dust is not the problem at all?
Well known problem ,,, Defective or poorly cooled chips failing. _ Sorry dude, - Bohanna
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post #10 of 24 Old 04-16-2014, 01:56 PM
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It's the DMD chip. You can get replacements on Amazon or Ebay. Pretty easy to replace, too. Just follow Youtube videos on how to replace them. It's like swapping a CPU. Just make sure you have some Artic Silver or other compound, as the DMD chip is connected to a heat sink.
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post #11 of 24 Old 04-16-2014, 02:18 PM
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Optoma had one or more models with the same problem because they tried to cheap-out on the heatsink paste. The chips ran too hot and only lasted a couple years. Apparently you can replace the DMD with the same one (using good paste on the back) and not have problems.

Simple <$250 dedicated black-fabric theater room, build in a day, takedown in an hour.
Easy $25-40 DIY black/dark-grey ambient-light rejecting screen, grab two things from a local store..mix..roll..done.
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post #12 of 24 Old 01-21-2015, 10:15 PM
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Any further news on this? I have a BenQ MP780ST with the white dots too. Is there any further action being taken against TI that might allow me to use leverage on BenQ to get a warranty repair even though my unit was manufactured in April 2011?

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post #13 of 24 Old 01-22-2015, 05:03 AM
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Quote:
Originally Posted by wekya View Post
Any further news on this? I have a BenQ MP780ST with the white dots too. Is there any further action being taken against TI that might allow me to use leverage on BenQ to get a warranty repair even though my unit was manufactured in April 2011?
Contact BenQ and tell them the problem and that it is a DMD DLP chip failure as Texas Instruments provide manufacturers including BenQ with a 5 year warranty on the DMD DLP chip. So they might be willing to repair the projector by replacing the chip for labour cost or for free.

These chips normally do not fail unless they overheat, that usually occurs due to poor installation of the chip as regards thermal paste to the heatsink or/and poor projector design as to cooling, unless the cooling is blocked up with dust or you have been using the projector in a very hot environoment.

I do not believe it is a problem with TI DMD DLP chips. The mean time between failures, that is the expected average life time of these chips is 100,000hrs of use. And TI stand by their product with a 5 year warranty to the manufactures of DLP projectors.

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post #14 of 24 Old 01-22-2015, 05:35 AM
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Oh Goodness, I wasn't aware of that problem, yet.

Back in the late 90's TI had gotten so annoyed with remarks "We don't have faith in the longevity of DMD chips" (e.g. Philips) that they asked the Munsel Color Institute to run an representative longevity test of a couple of LCD projectors vs. DLP projectors (not only did that test prove that DLP had longevity, it also proved that the DLP projectors outlasted all LCD test participants ). Times are changing, obviously.

So what are the statistics, if there are any, to determine at what point in usage time the problem - provided you have a DLP projector that could be affected - starts showing up?

My Optoma HD 83(00) from late 2011 has almost 800 hours of projection time. Am I on the "safe side" now, or do these defects usually not show up before one exceeded 1,000 hours, for example?

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post #15 of 24 Old 01-22-2015, 06:14 AM
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Definitely damage caused to the DMD by heat. I had the same problem with my Casio XJ-A240(now in the rubbish dump).
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post #16 of 24 Old 01-22-2015, 06:48 AM
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Quote:
Originally Posted by Frank714 View Post
So what are the statistics, if there are any, to determine at what point in usage time the problem - provided you have a DLP projector that could be affected - starts showing up?
If the projector has been competently designed and the DLP chip competently installed and the cooling is not clogged up with dust and you are not using the projector in a too hot environment then 100,000 hrs of use is the mean time between failures, the average life of a DMD DLP chip. So in heavy use say 40hrs a week you are talking 48 years. It should massively outlive some other components in the projector like the color wheel if a single chip design and cooling fans.
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post #17 of 24 Unread Yesterday, 05:25 AM
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Thanks guys! I'm going to take a poke at BenQ about the 5 year TI warranty thing and see what they say. I'm going to attach an image for future fellow travelers. It really looks like the Arctic Silver cooling paste didn't get spread to the edges doesn't it?

My dots started showing up well after 1000 hours. I'm at 1800 now, so it probably started at around 14-1500.
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It's just speculation that heat is the root cause of this problem. My tv developed the same problem, but it didn't go ballistic after the first stuck mirror. It got up to about 16 bright and 5 dark before it annoyed me enough to repair it, and that was over a period of about 3 months. My defects were mostly slightly off center, to the right. There was no thermal grease used in the tv design, only a thermal pad that appeared to be doing its job just fine. The interesting part was examining the chip under a microscope. It was strange to see lots of the tiny mirrors surrounded by reflective material, and based on what I saw on the screen, these mirrors still functioned properly (there were many of these). And it was also interesting to note that the defective mirrors looked to be completely coated with this reflective stuff, or they were stuck but it was hard to see since the tilt angle is pretty small.

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Quote:
Originally Posted by garciab View Post
It's just speculation that heat is the root cause of this problem. ...
No question that not all failures of any manufactured electronic part that lives in a hot environment are due to heat. There will certainly be a small percentage of parts in a big production run that aren't quite up to spec and could fail in other ways. But, any part that requires a heat sink or other means of cooling is most likely to fail prematurely from heat-related issues exceeding the operating limits of the part.

With DMD DLP chips, it's the projector manufacturer's obligation to provide adequate cooling in the projector design to meet TI's maximum heat specifications. As already mentioned in this thread they can screw it up in a number of ways, from inadequate heat sinks to inadequate air flow. As far as air flow goes, it's each owner's obligation to keep the air filters clean per the projector manufacturer's specifications.

It would be interesting to see the DMD DLP chip failure rate of various projector manufacturers and different models. TI probably has a fair handle on that from monitoring its own warranty claims. I'd expect TI to be aware of poorly designed projectors that result in higher chip failure rates and not be too generous with those projector manufacturers.
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post #20 of 24 Unread Yesterday, 11:49 AM
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I understand why the connection to heat is made, but consider that this failure has hit pretty much every OEM that used the DMD chips within a certain time frame. Also consider that there are many previous generations of tv's/projectors using older DLP chips that are still not exhibiting this issue. So either the newer generation of DMD chips required vastly improved cooling to remain troublefree, and all OEM's dropped the ball on their thermal designs. Or (which is what I believe) TI changed something in the DMD design/assembly in an attempt to remain cost competitive (this defect showed up in the generation when talk of RPTV's being doomed began) and didn't see the defect coming. Heat-related failures in semiconductors usually result in massive malfunction; here we see what appears to be more of a mechanical failure of the mirrors (mechanical failure is speculation on my part, as I don't know whether the mirror is stuck or the electronics controlling it have failed). Now, whether heat accelerated the rate of mechanical failure is unknown to us, but I guess it's possible. Only TI knows the root cause of why this gen of DMD's failed the way they did. Also note that regarding Mitsubishi DLP tv's, the repair never even mentions making sure a good thermal connection is made to the heatsink when replacing the DMD, so it's as if the cooling solution is fine. I'd also think that if cooling the DMD were so critical, there'd be a thermal sensor within it that would trigger a shutdown of some sort to prevent damage, as is the case with CPU's. And if TI is indeed providing free DMD chips to the OEM's for these repairs, do you think they'd do that if the failure was caused by poor cooling?

This is just my hunch, that's all. The reality is probably somewhere in between: a combination of heat and something TI changed in the way they make these little jewels.

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post #21 of 24 Unread Yesterday, 04:48 PM
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garciab, of course all of the fine details are required in order to make a good analysis, and some of the details you cite point more toward a TI design or manufacturing problem than one that's strictly heat-related. What I said in my previous post was more generic and didn't consider the added details that you've cited.
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post #22 of 24 Unread Today, 03:28 AM
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Quote:
Originally Posted by garciab View Post
I understand why the connection to heat is made, but consider that this failure has hit pretty much every OEM that used the DMD chips within a certain time frame.
Did it effect the premium DLP projector manufactures. The likes of Projectiondesign, Runco, Barco, Christie? And if it did were their larger more expensive projectors effected.
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Also consider that there are many previous generations of tv's/projectors using older DLP chips that are still not exhibiting this issue. So either the newer generation of DMD chips required vastly improved cooling to remain troublefree, and all OEM's dropped the ball on their thermal designs.
DMD DLP chips have become higher resolution and smaller in size so higher mirror density on the chip, they are also driven faster as in the number of times the mirrors tilt per second or what have you. The black coatings have also been improved a bit so more light absorbant. So I would guess that modern smaller higher resolution faster driven chips need to get rid of more heat. And obviously a smaller chip size means the light is focussed on a smaller object the chip so more heat.

But I expect the vast majority of failures are down to projector manufactures not faulty TI chips.

Consumer projectors are often very compact so the lamp is close to everything else and there is not much space for large fans inside or for air flow cooling. Noise is also seen as an issue with quieter better which means fans may also be releatively slow speed. Due to lack of space what space there is might be easily reduced by dust, and fans may also wear out over time and get slower.

Depending on design of the lamp housing the lamp reflector maybe not very efficient so resulting in more heat and might not be adequately cooled. Lamps are now often modulated to the color wheel segments and dymanic so they are at times overdriven so running hotter. The IR UV filter in some consumer projectors looks to be part of the projector not part of each lamp housing, IR UV filters deteriorate over time so letting more through the light path and causing more heat further down the light path. IR UV filters on some designs also appears to not be tilted so it is not deflecting the heat away from the light path.

The colorwheel maybe more light efficient due to clear segment or brilliant color segments which also means it will result in more light through the light path and so possibly more heat further down the light path.

The light integrator rod on most consumer projectors is a mirrored tunnel which is less efficent and generates far more heat than a glass rod light integrator. And over time may degrade so generating more heat.

On many consumer projectors the DMD DLP chip illumination has overspill around the chip which is absorbed so more heat. The light box in many consumer projectors is also very small so the heat from the light dump for the DLP chip offstate is close to the DLP and the lens may also be very close to the chip, and often a mirror or two, so again more heat. Overtime depending on what it is made of the light dump and other black areas may get bleached and so relfect light back onto the chip, that might also add to heat.

Consumer projectors are also cheap so possibly cheap components or less strnigent quality control in manufacture.

Consumer projectors often come with a manufacture warranty which is less than 5 years let alone 100,000hrs. So they may not be built to last and some of the things not built to last might adverserly affect DMD DLP chip life expectancy.

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Quote:
Originally Posted by garciab View Post
if TI is indeed providing free DMD chips to the OEM's for these repairs, do you think they'd do that if the failure was caused by poor cooling?
1. Some major partners of TI several DLP projector manufacturers are based in Europe. European nation wide or EU wide 5 year warranties are not uncommon due to national laws on products being fit for purpose.
2. A major selling point of DLP projectors is their life expectancy so it can be seen as a marketing ploy. Especially in the commercial and business projector markets where the projectors are often heavily used day in day out.
3. Consumer projectors are often treated as disposable when they die they are thrown away, I expect few people pursue repair years after purchase.
4. The mean time between failures the average life expectancy of these chips is 100,000hrs that is over 11 years continuous use, the TI warranty to manufactures is 5 years. I doubt they get many returns that are due to faulty chips prematurely failing rather than poorly designed or poorly assembled or poorly looked after projectors.
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I appreciate the interesting technical details you've added, dovercat. That's what I was referencing when I said all of the fine details are required in order to make a good analysis. The typical consumer doesn't really care about all the fine technical details. They're just pissed that their expensive toy died and want someone to make good on it or get even with someone by smearing their reputation, whether or not the object of blame is the actual culprit.
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