John & Anne Wiley

Intro
We bought an Optoma HD25e projector (similar construction to several other Optoma projectors) in July 2013 and liked it so much we bought another. It’s such an inexpensive way to have a giant HD and 3D TV & movie theater & monster computer monitor, we wanted to have a spare in case of problems and so we can take it on the road for presentations. We posted a review and a detailed followup on Projector Central soon after.

A couple of years later a flicker developed at the top-left (ceiling mounted) visible when viewing a white screen, and we knew dust could be a factor. So we opened the projector after reading what little we could find online, and eventually also opened the light engine itself, and cleaned them. We wrote the procedure up the procedure below in case it’s needed again, and decided to post it here in case it’s helpful for anyone else. It’s pretty scary and intricate to open the Light Engine, but it fixed the flicker and the picture’s brighter now. We’ll see if the flicker returns and maybe try a new lamp, since it already has 4500 hours though it’s still fine for watching TV in a bright room. We noted that lamps that have dimmer somewhat after a thousand or more hours may put out less heat, and thus be less prone to flicker.

Update 6/15/2022: We’re now of the opinion that there’s a digital part (logic chip?) deep inside the projector that overheats and causes the flicker. To the extent easily possible we remove dust from all electronic parts during cleaning and it’s helped a lot with flicker. Aside from frequent disassembly and cleaning, another strategy would be to add an external fan to increase airflow inside the projector. Ideally it would be built into a projector housing box with a large dust filter on the air intake and a bypass air intake flap that would open if the dust filter gets clogged without being noticed. Such a box would also reduce the already low noise level of this great little projector.

Here in SoCA we’d also like to have the input air coming from somewhere cool and the exhaust air going outside. Of course, big screen TVs have been getting better and cheaper (lower power requirements, less heat output, quantum dots, lighter weight…). Soon projectors may not be the best solution for our 93″ screen.

Update 11/14/2016: The flicker began to return a few days ago, and while exploring the menu to try varying settings I decided to try the built-in Help suggestion. When I pressed the remote’s <-‘ return button in the center of the four arrow buttons, the suggestion popped up to try the Frequency and associated setting. Doing that improved and then fixed the problem completely. Before disassembling your projector or buying a lamp, you might want to try that. It seems that few people have found this article so I’m not going into more detail but if anyone uses the Contact form here to ask, I’ll clarify further.

Opening the Projector

If you’re lucky, there’s dust in the lamp area and you can just remove that and clean inside the projector and clean the lamp assembly.

Warning: DO NOT use any sort of blower, air can, etc. inside the projector or you’ll run a very high risk of introducing dust into the Light Engine and that’s a massive and risky (but somewhat rewarding) hassle to clean. Use only suction inside the projector. We used a shop vac with a set of adapters and tiny attachments we got online.

Remove Top:
Remove the 3 screws from the bottom of the case, pull off the silver focus ring in the front and carefully pry open the case at the back and slide the blade of a tool (we used a slot screwdriver) along joint, and then open the front with the back tilted up while watching out for the ribbon cable (needs to be removed Before you completely remove the lid). The ribbon cable is clamped by a little Black plastic hinge that slides out and then up to release.

USE VACUUM ONLY INSIDE CASE. Using a blower will almost certainly introduce dust deep into the Light Engine. Vacuum everything you can reach, then use a soft brush to loosen more dust and vaccum again. Sometimes a thin film will still remain on parts, so we use a soft microfiber cloth on parts and a lens cloth and cleaning liquid on lenses. We sometimes also very carefully clean the color wheel, even though it’s risky and seldom makes any detectable difference.

REASSEMBLY
To install the lid, put the projector on its back and get the front of the lid in position first. Note that the Zoom wheel on the lid needs to line up with the pin sticking up from the top of the lens so that the pin goes into the slot on the wheel. There’s a big tab in the center of the case that needs to line up with the lid. Then click the lid into place by working your way around until it’s all the way down in place. Hold the corners of the lid in place as you tighten the three screws on the bottom of the case.

The focus ring has 3 tapered slots inside, that screws on the outside of the lens click into, so you need to rotate the ring so that it lines up with the screws on the lens and ensure that all three screws have clicked in when you insert the ring.

To Remove Color Wheel (risky):
Remove the two screws holding the sheet aluminum bracket to the base of the plastic case, and the two holding the color wheel assembly to the light channel of the Light Engine (between lamp and lens).

Don’t remove the screw holding the color wheel to the sheet aluminum bracket or the black semi-circular shield to the left of the color wheel (between wheel & lamp opening) will fall out and possibly damage the color wheel (plus it’s a dangerous hassle to reassemble).

Color Wheel Circuit Board Plugs

AFTER removal from projector and well away from it, vacuum and then blow off dust, then dust with a soft brush and vacuum/blow again, then use lens cleaner to remove film. It took several passes to get all the film and then streaks and specks of dust off the wheel, and shining a flashlight at close range from different angles helps to reveal any spots that still need work.

To put the ribbon cable back in, hold the cable in and carefully tilt the clip down, and push the clip all the way in.

IF DUST INSIDE LIGHT ENGINE (darker blobs visible on a blank white picture) or misaligned light engine or light channel (darker on a geometric portion of a blank white picture):
Safest to remove the Color Wheel first to avoid damage while juggling the larger parts.

To Remove Light Engine (very risky) & Circuit Board:
Remove the 8 screws holding the Circuit Board (arrows in pic), on the back outside case remove the 4 nuts (2 ea., metric) at the RS232 & VGA connection plugs & 2 screws beneath the HDMI plugs, and 4 holding the Light Engine.

(click to enlarge pic)

The 4 Light Engine screws are two at the base of the lens and two on the light channel that goes to the lamp (marked with felt pen arrows in pic).

(click to enlarge this pic)

Remove the Left screw holding the small shield onto the Circuit Board to get at the left rear Light Engine screw below it. The front Light Engine screw has a wire holder on it.

Tilt the whole assembly up and slide toward you out of the edge connection at back. The Light Engine is attached to the Circuit Board by an edge connector. Tilt the whole thing up at the Lens and pull the Light Engine out of the edge connector at the Circuit Board.

NOTE: With the Light Engine removed from the projector you can safely use a blower inside the projector. In fact, it’s a very good idea because dust insulates the heat-generating parts of the circuitry and power supply thus making them run hot resulting in failure. So with the Light Engine safely away from the area, we used the shop vac blower and attachments of all types and sizes along with brushes. We wore masks, because even after vacuuming carefully the blower made clouds of dust. After reassembly we noticed that the projector fan runs at a lower speed (quieter) than before, and that careful cleaning is the reason.

To Open Light Engine:
This bit can be tricky and potentially risky, but is required if there’s dust inside that shows on screen or if you’d like to remove any buildup of film that’s making the picture hazy.

The black plastic cover on the Light Engine has 4 screws.

Light Engine Bottom Cover

After you remove the screws be sure to flip the Light Engine over (so black plastic cover is on the bottom) before you open it or else the lenses will fall out. You don’t need to completely remove the black plastic cover, you can just pull the metallic braided tape that is at the base of the lens back a little so you can slowly flip the Light Engine right side up again until the black plastic cover sits on top of it with the lenses in place. Be sure to watch the lenses to make sure they release from the Light Engine and stay in the black plastic cover as you flip the Light Engine over. Then you can work on the Light Engine with the lenses sitting in the black plastic cover flipped over on top.

REASSEMBLY
Put the Light Engine into its approximate position. Note that the Circuit Board has slots that fit into tabs on the back of the case, so start by tilting the Circuit Board down at the back and inserting the tabs into the slots. Insert the Light Engine in to the edge connection, and tilt the whole assembly down into position.

With the Circuit Board/Light Engine assembly in position, put the 4 screws into the Light Engine and remember when you put in the front screw on the light channel, use the screw that has the wire holder.

To install the lid, put the projector on its back and get the front of the lid in position first. There’s a big tab in the center that needs to line up. Then click the lid into place by working your way around. Hold the corners of the lid in place as you tighten the three screws on the bottom of the case.

The focus ring has 3 slots inside where screws on the outside of the lens click into place, so you need to rotate the ring so that it lines up with the screws on the lens and ensure that all three screws have clicked in when you insert the ring.