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Mitsubishi WD-65734 light spots on black screen

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Old 02-09-2009, 10:50 AM   #1
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Default Mitsubishi WD-65734 light spots on black screen

Hello,

I have looked through the forums to see if anyone has had this problem with a Mitsubishi WD-65734 or similar DLP.

When the screen is black, such as when there is no signal, or in high dynamic range sources such as blu-ray when the screen is dark, I have recently noticed the left side of the screen has very subtle lighter spots, best described as smudges, that radiate from the bottom to the top of the screen (they are vertical) they are the width of a quarter, and are a few inches long.

I noticed a lot of talk of cleaning the projector lens and the mirror, so I took off the front of the TV (easy to do) cleaned the lens with a camera lens cloth and cleaner (it was dirty). I didn't mess with the mirror, it was still very clean. The TV is about 1.5 years old.

I also checked for "light leakage" around the lens - all of the foam is in place.

I also pulled out the lamp, and cleaned the glass "window" that the lamp shoots at. It also had some dust on it.

Smudges still there.

I am inclined to leave it alone, I really like this TV, the picture quality is spectacular, and the smudges to not seem to effect picture quality, they not visible when there is a picture on the screen. Turning up the brightness a bit also obscures them, and my eyes adjust to that very quickly.

But I am wondering what it could be and if maybe there is a more complicated fix. I suspect dust has gotten on something between the lamp and the underside of the lens (another mirror? DLP apparatus?). I do have electronic tech chops so doing a more in depth repair is not daunting to me at all. But I don't want to love the thing to death and I will leave well enough alone unless I am pretty sure another action will solve the issue.

Thanks for your responses.
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Old 02-09-2009, 12:44 PM   #2
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I posted a few weeks ago about a similar problem with my 2 yr old Mitsubishi 65831.
The bulb was replaced a few months ago, and I have recently noticed three distinct areas on the bottom of the screen that indicate light scattering - as noted with white film credits on a black background for example. It's one of those things that once noticed really annoys.
The lens can be accessed from two small removable panels on each side, BTW, and the lens is clean.
I'm with you in believing that a few dust specks have gotten into the light engine. The mirror chip is 0.6" across, so that's all it would take.
Here's the interesting part. I have a service contract, and they are going to replace the entire light engine on Wed. The new engine has been drop shipped to our house, and the tech is a good one, so we'll see.
If I didn't have the contract, I'd be in the engine with some dust off or something. I'll post when the job is done. Good luck with yours!
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Old 02-09-2009, 01:12 PM   #3
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Interested in how you get into the light engine there to get dust out without messing it up, if it is meant to be serviceable. Hmm, well they are swapping yours out - maybe you can watch and ask the service tech how it is done? I have a hunch that they are putting a "refurbished" one back in your TV, and will take yours back service it and put it in someone elses TV. Anyone ever gotten right to the DLP chip and lens and cleaned it?
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Old 02-09-2009, 03:02 PM   #4
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Quote:
Originally Posted by dithersail View Post
Interested in how you get into the light engine there to get dust out without messing it up, if it is meant to be serviceable. Hmm, well they are swapping yours out - maybe you can watch and ask the service tech how it is done? I have a hunch that they are putting a "refurbished" one back in your TV, and will take yours back service it and put it in someone elses TV. Anyone ever gotten right to the DLP chip and lens and cleaned it?
I think it is a refurbed unit since the box has a return label to get the old unit back to Mits. Cost on the invoice is $600.
You have no idea how I'm tempted to get into my unit. The service guy said that it might be an optical filter that is delaminating from the heat and that Sony has had that problem with their RPTVs. I think it is dust - it exactly mimics the look I would get on my Pioneer CRT RPTV when it needed a cleaning.
A fan appears to pull air through a filter screen in the lamp housing and then through the internal optics. No way that screen can keep everything out! I'll keep you posted about what turns up.
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Old 02-09-2009, 03:40 PM   #5
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Ahh yes very interesting. I noticed that there was no filter for the intake air to the lamp unit, just a screen that looks like it was designed only to keep large bugs and objects out, no serviceable fine screen that I could see. I could see several fans, one the traditional flat type, one more like a wheel (like a furnace blower). Both were dirty. It must pull all kinds of crud through the optics, even if the system is totally sealed up no doubt finer stuff would work its way in. It would be cool if you could do a bit of tinkering on the defective unit before you send it back (if you are responsible for that since they sent it directly to you). There must be an easy way use canned air to clean things off.

$600, Whew! Considering I paid $1500 for the thing from Tiger Direct, not worth it!!!
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Old 02-11-2009, 12:10 PM   #6
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It's fixed!! The new/refurbed light engine did the trick! The entire image has a crispness that it did not have before, and the halation along the bottom is gone.
This is proof that dust or ? does get into the engine. It seems to me very wasteful to replace the whole engine when a strategic cleaning would work, but after looking at the light assembly, cleaning the internals would not be for the faint of heart. I'm sure it can be done, though. Be very careful if you do it!
What amazed me was how close image alignment was after the replacement. Just a very slight touch-up was needed.
Yes, there are no less than three fans. If they move air, they also move particulate matter, and I didn't see any real filters anywhere. Like you said, the screen on the lamp assembly keeps gravel and small birds out. We are non smokers, and I imagine this problem would surely surface in a smoking environment.
At any rate, I usually don't buy service contracts, but thought it might be a good idea with a DLP set. Am I glad I did!
The service guy took the old unit with him, so I couldn't do a post mortem. Sorry.

Last edited by BANDB; 02-11-2009 at 12:13 PM. Reason: more info
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Old 02-12-2009, 11:54 AM   #7
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Just a follow up after an evening's viewing:
First my wife exclaimed about how "clear" the picture looked. Commercials that have lots of bright colors just popped. Good HD program material was stunning. Subtle detail in black areas was easily visible. White credits on a black background are absolutely crisp with sharp delineation. In other words, superb imaging like brand new.
I was fortunate to have a contract and a tech who was willing to gamble on a new light engine. However, we can't be replacing the light engine every couple of years because the optics get dirty. But who knows, maybe we'll have 65" LCDs for $1000 by then.
I'd love to hear from any more folks who have had this experience. There has to be a better way.
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Old 02-12-2009, 09:56 PM   #8
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thanks for sharing your experiences, you're right, there has to be a way to clean the optics if you have some technical chops. The picture on mine is still spectacular - only when the room and television is dark do you notice. Well enough alone. I'll check back every once in awhile to see if anyone has cleaned the apparatus themselves.
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Old 02-16-2009, 02:13 PM   #9
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We are not alone! http://www.hdtvmagazine.com/forum/viewtopic.php?t=8601 Scroll to bottom.
Googled "dust in dlp light engine" and got this among others.
FYI

Last edited by BANDB; 02-16-2009 at 02:14 PM. Reason: more info
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Old 02-17-2009, 10:53 AM   #10
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Wow! Interesting. I am not encouraged. It seems like it gets worse over time (makes sense as the dust accumulates). I have not noticed the "halo" effect. I am wondering if I should call mitsubishi anyhow and see if I can get them to show me some love. My set is 15 months in my house. Just out of warranty.
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Old 12-25-2009, 05:00 AM   #11
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Hello all.... New here. Let me start off by saying Merry xmas to all....

Ok, now my issue. I too have this TV and it just began doing that HALO effect. Mine is to the right side(about 10" in to screen) and some to the top left side and even some bottom left.... Very annoying, on black screens it looks like white haze and its driving me nuts. Only had the set for 2 1/2 years, and of course that half is out of extended warranty. My bulb went a few months ago, i replaced it..all went well....

Anyways, I thought dust, so I took off the case and cleaned the screen, glass looked good..... I was hoping this would fix the issue, yet it did not. I didn't even want to venture into the light engine areas, as im not 100% sure of success and don't want to make things worse.

Anyways, i see this is an older thread and perhaps someone else has found a way, or has figured something else out to do to alleviate this. My wife says it don't look to bad, but for me, man it likes stares me in the face and is driving me nuts.

Anyone have any suggestions, etc.. i sure would appreciate it.

Again a very merry safe and happy holidays to all...
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Old 12-25-2009, 09:58 AM   #12
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Quote:
Originally Posted by BANDB View Post
Just a follow up after an evening's viewing:
First my wife exclaimed about how "clear" the picture looked. Commercials that have lots of bright colors just popped. Good HD program material was stunning. Subtle detail in black areas was easily visible. White credits on a black background are absolutely crisp with sharp delineation. In other words, superb imaging like brand new.
I was fortunate to have a contract and a tech who was willing to gamble on a new light engine. However, we can't be replacing the light engine every couple of years because the optics get dirty. But who knows, maybe we'll have 65" LCDs for $1000 by then.
I'd love to hear from any more folks who have had this experience. There has to be a better way.
If you do eventually replace that DLP, plasma will be much closer in depth, detail and color range than any LCD available. There is just something unique to the plasma look, almost a 3D depth that LCD just can't reproduce. If you had a nice CRT or DLP, plasma is the next progressive step forward in viewing, LCD is a side and maybe even slightly backwards step. Not disputing the quality and beauty of the newest generation of LCD display panels as there are some excellent models available (at 2 to 3 times the price of a comparable plasma) but they still are missing something, call it perceptual depth...
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