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Discussion Starter · #1 ·
So I have been living with some annoying dust blobs dead center on my 20-HD for the past few months and finally I cracked. I'm a trained engineer after all, how hard can it be? After searching this forum and the web in general for advice on this I ended up just giving it a whirl and it worked out great! For any 20/70 owners out there who are suffering similarly, I thought I would post what I did exactly.


First of all, you know you have dust blobs when you see can see areas of color on an all black or all white image. My blobs were green and smack in the middle of the image, but I imagine it could be red or blue as well.


Before you get started you need some equipment:

- bright light or headlamp

- vacuum cleaner with soft bristle attachment

- standard philips screwdriver

- air compressor or compressed air can with directional nozzle


For the air source I used a little portable air compressor from Campbell Hausfeld. This is just a regular household air compressor of the sort you would use to inflate tires or whatever. The directional nozzle is one of those air hose attachments that let you inflate pool toys. The air compressor sends out air in rapid little pulses from the compressor piston, which I think was very helpful in dislodging the dust (I'll get to that part in a second), but I imagine a compressed air can would work OK as well.


My projector is ceiling mounted and so it hangs upside down. I left it in the ceiling mount for the cleaning and I recommend you do the same, so that the dust you blast out falls down and away from the machine instead of just settling back inside somewhere else. Be aware that later in this description that when I say "bottom" I mean the bottom side of the upside down projector hanging from the ceiling mount, which the would be considered the "top" if the projector were sitting on its feet instead of hanging. All clear? Good, lets continue.


Step 0: unplug the projector.


Before you start taking things apart, vacuum the area and then with a soft bristle attachment vacuum the outside case of the projector (not the lens though). Think "clean room". You don't want dust to be flying all around when you actually have the case off.


Next, take out the case screws. There are seven screws that you can remove completely, two on each side, two on the bottom toward the lens, and one on the back (exhaust) side in the center. All the case holes have little arrows next to them and the screws are the same size. After that, unscrew the two screws that hold the exhaust fan door closed and open the door.


Now you are ready to remove the case. It is holding on with friction now. I had success by pulling down from the back (exhaust) side. CAREFUL NOW! Two things to watch out for. First, the front part of the case has a long tongue that extends under the front case part that remains (up by the lens), so in order to fully remove the case you must slide it toward the back (exhaust) side until the tongue is clear. Second, the case that you just removed is attached to the guts of the projector with ribbon wire, because the case contains controls and LEDs. The wire is very thin and it doesn't seem like a good idea to let the case dangle by it. I didn't want to unplug the wires either, so I just hung the case over part of the projector. You might want to secure it some how so it doesn't fall or dangle.


OK, so now the underside of the projector is exposed... (yikes, lots of parts in there!). Don't touch anything! Just look with your eyes for now. There are circuit boards all over, but right in the middle behind the lens is a cube looking thing that is flanked on three sides by the red, green, and blue LCD panels (the fourth side of the cube facing the lens itself). Using your bright light or headlamp, inspect this cube and its LCD panels closely and get the lay of the land. You will see an air gap between the cube and the three LCD panels. Look into this gap and you can see the surface of each LCD pane... and probably notice that the surface of each panel is covered with fine dust... finally, we meet our enemy.


Get your air compressor and attach a directional nozzle, then fire it up. Let it run for a few seconds before going near the projector, to make sure it blasts out any dust that might be inside the nozzle. Then carefully take your air nozzle and direct the air blast into the air gap between each LCD panel and the central cube. Do not physically touch anything, let the air blast do the work. Take your time, it is a hassle to get the case off and on, and so you really want to make sure that you completely blast all areas of the LCD panel air gaps from various directions. I saw showers of dust raining down while doing this. Take the opportunity to air blast other chassis parts lightly just to knock away any other loose dust. Air blast the front of the lens too.


OK, pretty much done. Put the case back on (tongue first), attach all screws, and plug the projector back in. In my case all dust blob troubles where completely eliminated and the picture looked sharper than ever. Awesome!


Have fun,

-George
 

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Thanks for the write-up, George! I've done this w/the PJ down as I'm not willing to risk yanking the wires out and the Chief mount is a pretty quick-release setup. I do appreciate your comments re: gravity assist getting the dust out of the chassis. It really is easy, as you say. Only takes a few minutes. Not something to be scared of. Only had to do it once. I have some very minor blobs right now that are almost invisible even worst case (total black field). Got them by fumbling my filter removal one time (let dust from filters get inside when I removed them). I've started vacuuming BEFORE I pull the filters to get the bulk of the loose dust off. Just hold a dust-buster over the two outer grills and suck. It works pretty good as the mesh filters are always clean when I pull them out after vacuuming.


Gordon
 

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Discussion Starter · #3 ·
One other quick thing worth mentioning on Dust Blobs... I got my dust back when I was using the original dust filters that shipped with the projector. These filters looked like cloth or fiber of some kind and were just terrible... they had irregular gaps in the mesh and were hard to clean. I eventually tore one and called Studio Experience for a replacement. The replacement filters they sent me (for free!) were a very fine metal screen, with perfectly regular gaps, and easy to clean. A huge improvement. If you don't have this type of filter yet, contact your dealer and get them.
 

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Quote:
Originally posted by gbuzsaki
My projector is ceiling mounted and so it hangs upside down. I left it in the ceiling mount for the cleaning and I recommend you do the same, so that the dust you blast out falls down and away from the machine instead of just settling back inside somewhere else.
Leaving the PJ mounted has worked the best for me as well. I was cleaning mine every month or so until I tried it leaving on the ceiling. I haven't had to clean it again since. I attach a safety line (piece of string) from the mount to the cover to hold it while I'm cleaning.


I'd be careful using a compressor though. Apart from the fact that they're compressing room air (not necessarily clean), they'll also have some water and oil unless the line is run through a good filter.


Bob
 

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Becareful of canned air as well. If your can is tilted, goo can comeout and make a mess of your optics. LCD is 3 times as likely to get dust blobs and dead pixels due to its triple panels compared to DLP's one. Coffee filter makes a great air filter for your line when you are using a compressor. It does cut down on the strength. I personally use a hand pump used for kids long balloons (to make balloon animals) with a long tube attach to its nozzle (for directional guidance). I tape the vacuum nozzle with duct tape on the table near the area to be blasted to suck the dust away from the panels and my wife does the hand pumping while I guide my hose to the crack :D
 

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Discussion Starter · #6 ·
Wow, sounds like dust blob removal is more fun at Huey's house!


And now, to end my experience on a very slight downer... here is the official response to my inquiry from Boxlight Technical Support:


"Sir, If your projector is under warranty you will want us to do this. If you open the case of the projector then your warranty is void. Please call us at 1-800-762-5757 and let us know what the serial number of the projector.

Regards..."


Ha Ha, just kidding everybody... this never happened. Never happened... never happened...
 

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Very funny, George ! You had me agog for a minute. :)


Gordon

Easily Gogged
 
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