# Dust *IN* the lens?



## patchesj

I have an AE-2000U and it appears I have dust behind the front lens. I see no "easy" way to even get in there with some air to blow the dust out. The specks create very slight green dots on the screen during extremely dark scenes. Help! Thanks.


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## lcaillo

The green spots are almost certainly debris farther back in the light path. Dust in the lens as you describe is so far out of the focal plane that it does little other than create diffusion, which may be visible as a darker area but mostly just reduces contrast. A colored spot is usually on one of the light paths before the prism and after the dichroics.


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## RBTO

The previous poster is quite correct. Small specks of dust in the polarizer assemblies produce out-of-focus "fuzz balls" on the screen, usually on a dark field. There is a cleaning procedure in another forum on this, but here it is in abbreviated form.

First pop the top. This hinges back up and comes off after the two retainers are removed that limit it from falling off. Now you need to remove the lamp and remove the screws holding the inner shroud. These screws are marked and the shroud comes off by lifting it directly upwards.

You'll see the three slots in the PC board where ribbon cables go though to the LCD assemblies. Use caution and some canned air to blow downwards in these slots. _*Make sure not to let any liquid from the canned air get sprayed into these areas.*_ It's best to use a can that is mostly depleted and hold it upright while spraying to prevent this. Spray on both sides of the ribbon cables. Reassemble the projector and check it out. If this didn't remove the dust, you might want to go further, but read the cautions!

*SECOND LEVEL SERVICE SUGGESTION - PROCEED ONLY IF MECHANICALLY and ELECTRONICALLY INCLINED.*

If this didn't work, you will need to remove the PC board ------- CAUTION!!!! This requires some mechanical and electronic experience - not for the faint hearted.

CAUTION: The three ribbon cables (which go to the LCD assemblies) _*are held in zero insertion force sockets *_at their ends. There' s a little white tab that flips up to release them. _*You have to release them before any attempt is made to pull them from the sockets.*_ Once the tabs are flipped, the ends of the ribbon cables will come out easily, with little force. _*Make sure you are grounded to the frame of your projector before you touch the board or do this.*_ Once the ribbon cables are out, CAREFULLY remove all the edge connectors that go to the PC board. This requires skill and you might not want to do this unless you are experienced. Don't pull on the wires going into the connectors! Grasp the body of the removable part and wiggle it out. If wires get broken, your looking at a big repair bill a la Panasonic!

Remove the screws holding the PC board (hope you are still grounded to the projector frame) and lift the PC board up and out (the rear input connector assembly comes with it). As you are removing the board, feed the ribbon cables though the slots so they aren't damaged. Set the PC board assembly aside, and use your compressed gas to spray all around the ribbon cables (_*no liquid spray into the spaces!!!!*_). You should have a lot more clearance now that the PC board is out. While you are at it, you might want to wipe down the interior with a dust cloth. A microfiber cloth works well. Don't use anything that will shed.

Reassemble, taking care when feeding the ribbon cables back up through the PC board slots. Make sure all the edge connectors are clear when seating the board. Once the screws are back in, insert the ribbon cables and snap the locks. Reinstall all the edge connectors making sure they fully snap in place. Install the shroud, lamp, and top cover, and test. You should be free of dust specks.

Do the procedure at your own risk. It is not that hard for someone who works with electronics, but there are things that can go wrong (static discharge, broken wires, etc.), so it can be a somewhat risky procedure. Do it in a clean area and don't introduce more dust that you remove. Clean your air filter while you have the projector apart and clean around the filter mount (with the filter out) with a vacuum to get any loose dust. If done properly, you can get a near perfect dark field when you're done.


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## Gregr

I hope You have not gone in with the canned air before you've had a chance to consider using a vacuum instead. If your DLP or camera, projector, etc. has dust behind the lens (first place to try) hopefully it is behind the lens. Blowing the equipment clean is always a good idea and with expensive equipment it may be best to leave that for professionals but if you want to clean out a few pieces of dust or debris it will more likely be quicker and easier to vacuum. Little chance of stirring up additional dust and debris and driving this into smaller crevises still.

If you don't want to invest in sears micro vac parts than you can create a small vacum using a can of canned air and plastic tubing. 

I can describe that to you if you need.., just let me know

Greg


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## Gregr

Ha, Ha , one small question..., how did this post end up in the "new posts" column? I don't see recent posts.

Greg


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## Gregr

Nevermind!?> :yikes: I'm still learning.

Gregr


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## RBTO

Gregr said:


> I hope You have not gone in with the canned air before you've had a chance to consider using a vacuum instead. If your DLP or camera, projector, etc. has dust behind the lens (first place to try) hopefully it is behind the lens. Blowing the equipment clean is always a good idea and with expensive equipment it may be best to leave that for professionals but if you want to clean out a few pieces of dust or debris it will more likely be quicker and easier to vacuum. Little chance of stirring up additional dust and debris and driving this into smaller crevises still.


Unfortunately, problems with "dust blobs" in the AE2000 is not dust behind the lens. It is dust on the LCD and polarizers which lie some distance behind the lens. A speck of dust appears as a "blob" because it is substantially out-of-focus and not in the same plane as the LCD itself.

A vacuum will not work (although I highly recommend it for cleaning up around the air filter area and within the projector case so as not to scatter the dust there) since you can't get the tip to where the dust particles are located (without completely disassembling the LCD/polarizer assembly - not at all recommended). The particles are attached to the optical elements with a slight static charge which immobilizes them, and a pressure type cleaner must be used. It would be similar to trying to remove particles from a CD working from the outside edge only. Likewise, you wouldn't want to risk having the tip of any cleaning device where it might contact the LCD or polarizer leaving _any _kind of a mark on it. As long as one takes precautions not to allow any of the liquid propellent to enter the optics, scattering the particles to other locations is a sufficient cure for the dust blobs as they tend to exit the system with the cooling air rather than return to the optics.

My cleaning procedure is specific to the AE2000 and may not apply to other projectors. I agree that a cleaning job is best left to professionals, especially if one has no experience taking this type of equipment apart. The original poster didn't indicate their skill level, but it's wise to have it done professionally if there are any doubts. Unfortunately, it will cost a substantial fee, and the AE2000 most likely will need to be sent to a service depot since very few "repair" shops are equipped to handle this procedure. I do know that some who read this forum are very skilled in such matters, and can do the procedure successfully, however.


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## Gregr

Hello RBTO,
.
You've done a great job of describing the process and I am inclined to agree there are many qualified people here on HTS and you have given them specific instruction enough to do a complete cleaning. I was concerned that somebody might try to do a quick cleaning and instead of blowing the system clean they now have dust everywhere esp. on static charged plates/parts and nothing less than a complete cleaning will do. Because I have done similiar things thinking "well I'll just do a quick clean for tonight" and end up with something unusable.
:unbelievable: :huh:

Thanks

Greg


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## lcaillo

You do have to be very careful with cleaning in these systems. It is very hard to get dust to move, but sometimes if it is a large enough to be discretely visible, it is more likely to move with air. The propellents are a problem and can damage a filter or panel if sprayed directly on them.

This is a problem that most people just don't get about LCD light paths in projectors. You simply have to expect that the image will deteriorate over time as dust and oils collect in the light path. The cleaner you keep the air, the longer before it is a problem.


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## patchesj

Great advice, I love this place.... I consider myself mechanically and electronically inclined, circuit boards don't scare me and I happen to have more than one grounding strap (but I'll admit, not used as often as I should..).

I've opened the case and removed the PC board. Spent quite a bit of time looking around the optics without any additional cleaning attempts. Did some very quick and "light" air can dusting and reassembled. Tested and I've taken care of most of the smaller blobs. Still have one or two, not sure if I'm going to take it apart again or just deal with them. They are VERY faint and not very large, I'm sure I'll be the only one to notice but they might drive me insane.

Thanks again!


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## RBTO

Glad it worked out for you. Once you've done the procedure and get a feel for it, it isn't so intimidating, but I'm still set back with all the edge connectors which have to be disconnected in the AE2000, and removing the PC board more than once just multiplies the risk there. I'm like you. I had a good collection of dust spots going after 2 years of use and finally said "that's it", and bit the bullet. After cleaning, I had only one very slight blob left, of which I'm sure, I'm the only person that will ever notice it. Actually, I have to be looking for it, before I can see it, so I consider the job a good success.

Greg has a good point. It amazed me how much dust was in the "inner sanctum" of the projector when I first opened it. I did a thorough vacuuming after lifting the cover, and again, when the inner shroud was removed. The inner area should be protected by the air filter and positive pressure, but it still had significant dust on most of the plastic parts (which, fortunately, seem to hold onto it). Vacuuming cannot be overrated to get this potential problem out of the innards, as long as you're in there. Some of the dust clings tenaciously and a "sticky" cloth will help wipe it off the areas where the vacuum doesn't get it. The reason I mentioned vacuuming the filter holder while the filter is out, is because removing the filter dislodges a bit of dust on the wrong side of the filter, and unless it is removed, it will be sucked into the projector, the next time it is powered. I both vacuum and reverse blast (in that order) the filter while it is out, and then give it one more vacuuming before putting it back in (good procedure any time you clean the filter).

Anyway, glad you were successful. Notably, it's been about 6 months since I did mine and the only spot I have is the almost invisible one that I had right after the procedure. I'm not going back after that one!


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## patchesj

OK, so I lasted a few hours before I went insane.. Took it back apart, blasted the optics again with air. No blobs anywhere... Woot. Thanks again!


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