For those who do not know what a "dust blob" is, it is when a spec of dust lands inside the imaging mechanism (lens and/or mirrors, etc.) of a projector. Some may think, "big deal, its a tiny spec of dust". Well, given the nature of projectors, this pin sized spec of dust gets magnified a billion times then is conveniently projected right out onto your movie screen resulting in most cases as a blurry hexagonal shaped "light " spot on the screen. This spot is typically just a shade lighter than the overall displayed image on the screen and is most noticeable when the video/image being displayed from the projector is black. The size or quantity can vary, obviously, however in my case the dust blob was approx. 5-6inches wide.
At first I tried to look past "the blob" and enjoy the movies however because I knew it was there, my eyes were always drawn to it which would tend to ruin my movie watching experience. This is when I decided to hit up Google for some info but to no avail, it had looked as if nobody had come up with a way to fix the problem. One guy was lucky enough to have this exact issue within his warranty period, so he sent the projector in to Optoma.............then never updated his blog with a status. This is where I come in. I refuse to let a particle of dust, drive me or anyone else to insanity. So I held my breath, ripped apart my HD70 projector, FOUND THE PROBLEM!!! and worked up the below instructions in hopes that it will help you guys as well.
My Google search returned quite a few results of people trying to resolve this issue on this exact model projector, so I hope this helps them out!
- Medium sized Philips screw driver
- Small flat head screw driver
- Cotton swab (Q-tip)
Step 1) If the projector was in use, make sure it has been set to cool down for at least 30 minutes to prevent damage to the bulb during dis-assembly. (per the warning label)Step 2) Turn the projector upside down and remove the 2 Philips screws for the bulb cover.
Step 4) Unscrew/loosen the 2 Philips screws that are holding the bulb casing in place.
Step 5) Flip the metal bulb casing handle upwards and gently pull straight up while "wiggling" the casing slightly back and forth, then carefully set the casing aside where it will not get bumped/dropped.
Step 6) Remove the 3 Philips screws that are holding the plastic front casing of the projector together.
Step 7) Flip the projector upwards so that the lens is facing the ceiling and so that you are looking at the underside of the projector.Step 8) Using your thumbs, put upward pressure on the casing as to push the casing away from you. You may have to wiggle it a little however, once the the side closest to you pops loose you can then slowly lift the front casing upwards and away from the main body of the projector.
Step 9) Once the front casing is free, you must disconnect the wires to the IR sensor by separating the wire clips, then set the front casing aside.
Step 10) If you have a lens cover, (as seen in the photo below) place it over the projector lens to prevent any damage to it.
Step 11) Remove the top 2 Philips screws (circled in red) on the back of the projector.
Step 12) Flip the projector over and remove the following 3 screws which hold the top casing of the projector in place. (2 by the bulb housing and 1 on the opposite side of the projector)
Step 13) Place the projector upright and you should now be able to wiggle the top cover of the projector loose. Note: On my HD70 there was sticky tape on the back left side, (see below in red) which I had to separate from the top cover to get it loose.
Step 14) After you pull the top cover off you will notice a ribbon cable that connects the projector buttons to the main circuit board. Pay attention to the direction in which the ribbon cable is plugged in and then proceed to carefully pull the cable out from the main board then set the cover aside.
Step 15) Now turn the projector sideways so that the main projector lens is closest to you and look for the wire clip below and lens access panel. Once you have found the wires and access panel, remove the wire from the main board so that you have a clear view of the lens access panel.
Step 16) Remove the 2 Philips screws holding the black lens access panel in place. (Removing the black foam piece is optional)
Step 17) IMPORTANT: Make sure the projector is in a dust free area! Then, using your small Flathead screwdriver, carefully pry up the corner of the access panel to loosen it.Step 18) Remove the access panel to expose the inside of the main projector lens assembly and set it aside.
Step 19) I do not have photos of this next process however as long as you are careful, it was quite easy:
a)The main projector display lens is located inside and to the left. (see red arrow)b) Remove the rubber main lens cap that we installed in "Step 10)" then turn on your flashlight and shine it directly into the main lens from the front side of the projector.
c) By carefully looking into the access panel, (photo above) you should now be able to see the reflected light from your flashlight in the the display lens. I created a diagram below so you can understand the point of view.
Step 20) By moving the flashlight up and down and from left to right you should be able to easily spot the dust (tiny bright specs) on the display lens inside the access panel. Note: Be careful not to breathe or accidentally blow air into the main lens assembly.
Step 21) Next, take a clean dry cotton swab (Q-tip) and through the access panel that you are looking through, very gently brush the dust off of the display lens by applying very MINIMAL pressure. Continue this procedure carefully until you no longer are able to see the dust specs on the lens.
Step 22) Once you no longer see dust on the display lens, proceed to cover up the lens access panel and carefully reassemble your projector in the reverse order that we have taken it apart.
Step 23) Your done!! Plug in your projector and try it out!
I had excellent results when cleaning the display lens using these steps and I no longer have "dust blobs" on my screen!
I hope that my time spent putting these instructions together helps you guys out there that have been looking for answers (like me) and could not find them.