HD66 Dead Pixels repair thread - collecting info to do a step by step tutorial. - AVS Forum
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post #1 of 9 Old 11-13-2012, 02:41 PM - Thread Starter
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I bought my projector about 3 years ago. I think I was the first one on avsforum to get one, and I put up a review. A few months ago my projector had a few dead pixels one day. I am up to 13 now. I am adding a new one every week give or take. I sold my movie chairs, and I am buying a new LCD for the living room. I am not sure if I am going to hook the projector up anywhere in the house. If I do, it will be less dedicated and likely an electric/remote control drop down screen from the roof from ebay for 150 or so. The DMD chip is what is wrong from what I read, and I don't see anything else that would cause it. As for DMD, I see many of them on ebay for about 125, and on some of the import companies for about 80 or so.

I found one website or post with directions on taking apart a hd65 which is about the same from what I understand.

I am probably going to go ahead and fix it. I am sure there are more than a few people here who would like a step by step tutorial to changing it. I am willing to take pictures and write down exactly what I am doing to fix it.

I do have a few questions, if anyone can help me with the answers.

Is there any of you who have done it that can give me tips or hints?

Is there anything else that needs to be done while I am in there?

Getting hot causes the mirrors to fail as far as I understand the issue. What happens to the mirrors? Is there any way to heat it up by running it without the heatsink or maybe tap it on a hard surface and have a chance of getting them back into position or something? Maybe a blast of electric cleaner on the mirror surface? Playing with the old one can't hurt, I'd like to try and resurrect it.

I have Artic Silver 5 that I use on PCs. I have never once had one dry out and go bad when using quality stuff. I think I would prefer to use this as opposed to what comes on the chip as obviously whatever is being used on them isn't the best. If any of you removed the paste, how did it look? I worry about removing the paste carefully because of all the mirrors. I can't imagine getting alcohol or thermal paste on the mirrors would be a good thing.

I have a lot of things like stick on PC memory unit heat sinks and such. I will be looking for the possibility of improving the heat sink situation on the unit while I have it apart and considering the idea of adding a fan or something to the side of it if there is room. Anyone have any input on this?
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post #2 of 9 Old 11-13-2012, 04:10 PM
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I was in a similar predicament a month ago. My nearly 2yr old Acer H5360 developed a stuck mirror, shinning white, near the center of the screen. Only 1500 hrs on the unit. So I had planned to do exactly what you are planning to do, purchase a DMD from China and fix it myself, using ArcticSilver.

Well, after not using the PJ for about 2 weeks, I used it in 3D mode + high lamp for a few days, and the mirror started to function again. So far 50hrs use later and still good. So I don't know what did it. I would suggest just trying to apply the Arctic Silver compound first on the present chip, or run it with high lamp + 3d for a while.

If one stuck mirror can fix itself, then it should work in principle for all of them.
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post #3 of 9 Old 11-14-2012, 03:00 AM - Thread Starter
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I may take the current chip out and spray it down with electric cleaner spray and see if it affects the mirrors before I order a new chip. I know it is a overheating problem but is the problem due to the thermal paste drying out and becoming powdery and maybe falling into the mirrors. They are tiny and a bit of powder would easily hold a mirror open or closed I would imagine.
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post #4 of 9 Old 11-14-2012, 06:29 AM
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There is nothing inside the DMD, no thermal paste or any other matter. I don't know where you got that idea. Perhaps you should look at this...


http://www.optics.rochester.edu/workgroups/cml/opt307/spr05/john/
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post #5 of 9 Old 11-14-2012, 02:11 PM - Thread Starter
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I know what they look like but I never saw one in person, just pictures. I didn't realize there was glass over the mirrors but it makes sense. The reason I believe there is thermal paste is because every post I see about people changing them or having issues involves the thermal paste. I don't think I implied the thermal paste was in the chip as much as on it. The statement about getting the dust in the mirrors was because I didn't realize there was a piece of glass on it. I have obviously never taken a DLP apart.smile.gif


This is a similar optoma model and really is a decent video and I am sure the projectors are very similar.

https://www.youtube.com/watch?v=uJpGvrz3yR4

At 19 minutes or so he takes the actual DMD chip out, you can see the thermal pad there. This pad is why the chips stop working from my understanding due to excess heat because they used a cheap garbage thermal pad. It looks like it has a pretty decent heat sink and that there would be enough room for me to put a cooling fan on the heat sink.

Does anyone know if the electrical inside is 110v or 12v or some other random 53v or something? Id like to have a fan ready in case I decide to put one in when I take it apart. Thanks.smile.gif
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post #6 of 9 Old 11-17-2012, 03:23 AM - Thread Starter
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I successfully took apart the projector and changed the thermal pad to artic silver 5 today. I have at current 15 dead pixels. I have been adding 2-3 a week to the count. It was not terribly hard. I did it today because I wanted to stop the decline of the projector and also because I wanted to make sure I could do it before I spent 125 on a new chip. Also, I wanted to make sure the artic 5 would work.

A list of things I noted that might help someone in the future. I will still make a video or take pictures when I actually fix it.

1) Pulling the top off is load and sounds a lot like breaking plastic. It comes apart though.
2) It is pretty easy.
3) I left a few of the cables off the first time. The second time was a lot faster.
4) I realized I switched the IR and the color wheel connector the second time.(color wheel goes on the left, IR goes on the right.) They both fit and look identical.
5) After putting it back together the third time, I can change a DMD chip in about 15 minutes.
6) I didn't realize my projector only has 900 hours on it.
7) The thermal paste came right off with the tip of a screwdriver. It is no wonder it was overheating. I spread artic 5 on it, and it seems to be ok.
8) The lens/dmd/color wheel assembly is taped under it and maybe pressure fitted. It takes some tugging to get it loose even though everything is disconnected. The color wheel is what I worry the most about since it is just sitting in the open.
9) While it is about 25 screws or so, they aren't too bad.
10) You will need 2 sizes of screwdrivers, and one needs to be a long skinny small tipped magnetic one for the screws on the lens assembly.
11) The two ribbons connect in different ways. The one on top of the case flips, the one of the board pulls out and not very well. The one of the case will surely get pulled loose when you take it apart, it isn't a big deal - I pulled it off accidentally 4-5 times. It is a sort of L shape. The small end hooks into the projector, the long end into the case. You should hook the small end first if you want to put it together easier.
12) I accidentally touched something and left a fingerprint or something somewhere. I will fix this when I replace the DMD chip. I figure I will use alcohol on a cotton swab and then blow it off with(haha) compressed air. Is there any better way?
13) The video I posted is about 95% accurate and everything is real similar. A few screws/ribbons that don't match up.

Ill follow up when I get the new chip.
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post #7 of 9 Old 11-17-2012, 10:50 AM
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Thats awesome! I can't beleive some people are ready to ditch a PJ when a problem arises. Its surgery time smile.gif

I think these kind of threads are really important. I think Texas Instruments screwed up in designing these 720p DC3 120hz chips, as there are dead pixel issues accross all brands that use them, Acer (mine), Optoma, Benq....

I think you should wait and see if any of your mirrors start functioning, or atleast stop getting further stuck mirrors, then you'll know the next chip you put in will last a really long time.

If my stuck mirror returns, I plan on doing exactly what you did and try to prevent further damage.

All the best, and please keep this thread going. I ordered a couple of tubes of Arctic compound as well in anticipation.
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post #8 of 9 Old 11-17-2012, 07:22 PM - Thread Starter
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We will see how it goes. I plan to use it for a week or two, the 15 pixels that are currently dead don't keep me from using it to play the XBOX, so it isn't a big deal. I don't know if I could watch a movie on it like that as they are bright white pixels. I am buying a new TV in a few days though, so I am not terribly worried about it. I can definitely change it myself which is awesome, and I am going to find out if the DMD chip thermal paste was the issue.

If anyone is interested, you can probably put a PC fan on the heat sink pretty easily. It is completely open on one end of it.

Do you think it is the DMD chip itself or the poor performing heat removal? If my pixels crapping out stops, then I am going to assume the DMD chip itself isn't the problem and I will definitely change it out with a new one using the arctic silver 5. If you use AS5, then you might want to watch a movie on all high lamp settings after installation. It does have to cure somewhat, but is probably much better than the thermal pad right off the bat. It has to cycle cold and hot a few times before maximum heat transfer. It does, however, do better uncured than thermal pads/tapes.



Here is a chart of common PC thermal pastes. You will see Arctic Silver is pretty awesome. However, there are others that might be cheaper and/or better than AS5 in this usage. I used it because I trust it to be better than the pad and I have enough to last me forever.

I considered ditching the projector because I saw a HD67 unopened in the box for 450 locally. smile.gif I would of still ripped this one apart. After I checked and saw I only had 900 hours on my bulb and all of that at theater black I decided to salvage it. It is almost new still!

When I take it apart next time I will definitely take pictures.

-David
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post #9 of 9 Old 11-18-2012, 03:12 AM - Thread Starter
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It would probably help if I explained that chart. The numbers are the difference between ambient temperatures and core processor temperatures on a CPU. All the tests were done on the same CPU and the lower the number the better the thermal paste transferred heat from the CPU to the cooler.
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