Barco DP2K-10S – Blue Blotch Bottom Right (Prism Contamination or Blue DMD?)

[Fandi Arbianto Dewanggi]

Hello everyone, I am a cinema technician from Indonesia, I work in an independent cinema, so I have minimal fellow technicians.
I am currently operating a Barco DP2K-10S . Recently, I noticed a permanent blue blotch appearing at the bottom right corner of the projected image.

The blotch is always blue, regardless of the color being projected.

It is most visible on a full white test pattern, but it can also be seen (less strongly) on all colors.

The position is fixed and does not move.

The appearance is more like a blurred spot/cloud, not sharp pixels or lines.


What I have already tried:

Cleaned the porthole glass.

Removed and reseated the lens.

Swapped lamp house with another unit.


In all cases, the blotch remains the same.

My questions:

1. Do you think this is prism contamination rather than a failing blue DMD?


2. Has anyone here successfully cleaned or refurbished the prism block or dmd chip in a DP2K-10S light engine?


3. Would replacing the blue DMD chip solve this, or is it more likely that the entire optical engine needs servicing/replacement?

20250920_232452.jpghttps://drive.google.com/file/d/1FA1ka9Zn6daO6hj9jH8tyvpH-VYRveBY/view?usp=drivesdk

I attach sample pictures of the screen output for reference (white test field, with the blue blotch visible).

Thank you in advance for your advice and experience.

Best regards,

[Marco Giustini]

that is not likely an issue with blue. The spot is cyan. Cyan is Green and Blue together - so a cyan spot on a white field means there is not enough red on that spot. If you put up a RED pattern, you should see a darker spot there.

First of all: work on a full container image when diagnosing. That is Scope, half of your chips are not being used.

Then move the lens left and right: does the spot move with the lens? If so, the issue is in the projector, if not, it's porthole/screen (unlikely). You say "the position is fixed", can you clarify?

A coloured patch is likely inside the engine so not much you can do - at least officially. But it's worth checking the integrator too: you can adjust it a bit, if the patch of colour moves with it, you've found the issue. If it doesn't, then the issue is further down the line. DO NOT touch anything unless you know how to re-adjust things.

[Steve Guttag]

Agreed. This will be a contamination in the optics to the RED DMD. Something is likely obstructing it like dirt or a liquid contaminate. I suspect if you put up a full Red (like you are shooting colors), the contaminated area will be there but not on Green or Blue.

[Leo Enticknap]

The only other possibility I'm wondering about is an issue with the cold mirror. Fandi writes that he swapped a lamphouse unit, which rules out the lamp, reflector, or UV filter. I was once asked to look at a DP2K-20C with a reddish patch visible on a white test pattern. The first thing I discovered was a yellow tail light, and the cold mirror fan (the one that sits above it, immediately below an air filter) out. That had caused the mirror to overheat, resulting in a diagonal crack across most of its length. With the fan and mirror replaced, the reddish patch went away.

[Miguel Moreno]

How difficult is it to clean the dust on the red DMD?

[Marco Giustini]

I've never tried myself but Manufacturers have dust-free rooms for that. Formatters must be torqued properly and I feel it's easier to make it worse than anything else.
If the engine was dead or unusable and no repair/exchange option, then why not. But in your case it might mean having to source a new engine urgently!

Also, bear in mind the issue could be with the prism itself, some glue might have failed on the Red path.

[Caleb Williams]

Can you post a pic of only the red test pattern? It is possible to clean the prism, extremely carefully, but any contact with the prism should be avoided.

If it does turn out to be a spec of dust, a can of compressed air with no additives can be used to carefully push the dust out.

[Fandi Arbianto Dewanggi]

that is not likely an issue with blue. The spot is cyan. Cyan is Green and Blue together - so a cyan spot on a white field means there is not enough red on that spot. If you put up a RED pattern, you should see a darker spot there.

First of all: work on a full container image when diagnosing. That is Scope, half of your chips are not being used.

Then move the lens left and right: does the spot move with the lens? If so, the issue is in the projector, if not, it's porthole/screen (unlikely). You say "the position is fixed", can you clarify?

A coloured patch is likely inside the engine so not much you can do - at least officially. But it's worth checking the integrator too: you can adjust it a bit, if the patch of colour moves with it, you've found the issue. If it doesn't, then the issue is further down the line. DO NOT touch anything unless you know how to re-adjust things.

Hi Marco,
Thanks for the helpful insight! I ran a full RED test pattern as you suggested, and indeed the spot appears as a darker (almost blackish) area on the red pattern (in the photo it is not clearly visible but it will be visible to if you look closely). This suggests, as you said, that it's not actually a blue dmd issue, but rather a lack of red in that area, creating a cyanish blotch on a white field.

Additionally, I noticed that when I shift the lens position upwards, the blotch moves along with the lens movement. That means the spot isn't absolutely fixed on the screen, but is tied to the image path through the lens.

So it seems like the issue is indeed related to prism contamination or something obstructing the red channel internally, as you suggested. Do you think replacing the DMD red can solve the problem? Because for me, it is very difficult to clean the prism block, because I am not an expert and do not have a dust-proof room.

[Fandi Arbianto Dewanggi]

Agreed. This will be a contamination in the optics to the RED DMD. Something is likely obstructing it like dirt or a liquid contaminate. I suspect if you put up a full Red (like you are shooting colors), the contaminated area will be there but not on Green or Blue.

Hi Steve, thanks for the helpful insight!
You are absolutely correct. I ran the test patterns:

On RED, the blotch shows up clearly as a dark spot.
On GREEN and BLUE, there is nothing visible.

So it matches exactly what you described – the issue is in the red channel.

In your experience, what would be the best course of action from here?

Would replacing the red DMD solve this?

Or is this more likely to be contamination or obstruction somewhere in the red optical path (prism or cold mirror), meaning a DMD replacement would not fix it?


I really appreciate your guidance – this is my first time encountering this type of contamination issue.

[Fandi Arbianto Dewanggi]

The only other possibility I'm wondering about is an issue with the cold mirror. Fandi writes that he swapped a lamphouse unit, which rules out the lamp, reflector, or UV filter. I was once asked to look at a DP2K-20C with a reddish patch visible on a white test pattern. The first thing I discovered was a yellow tail light, and the cold mirror fan (the one that sits above it, immediately below an air filter) out. That had caused the mirror to overheat, resulting in a diagonal crack across most of its length. With the fan and mirror replaced, the reddish patch went away.

Hi Leo,
Thank you for sharing your experience. That’s very interesting

I will check the cold mirror and its cooling fan as you suggested, to see if there is any sign of overheating, cracks, or coating damage. If the fan has failed or the mirror surface is compromised, that could explain the issue.

Thanks again for the valuable insight!

[Fandi Arbianto Dewanggi]

Can you post a pic of only the red test pattern? It is possible to clean the prism, extremely carefully, but any contact with the prism should be avoided.

If it does turn out to be a spec of dust, a can of compressed air with no additives can be used to carefully push the dust out.

Hi Caleb,
Thank you very much for your advice. I tested with the full RED pattern and the blotch clearly shows as a dark spot, while nothing appears on Green or Blue. So it definitely confirms the issue is in the red channel.

Thanks for the suggestion about cleaning the prism. I'd actually like to try that, but I am not confident to attempt this myself, since my environment is not dust-free. I understand that even a small mistake or contact with the prism surface could cause permanent damage.

Thank you again for sharing your experience and advice. It really helps me to understand the situation better.

[Steve Guttag]

My guess is that the issue is on the prism and not the DMD itself. If a DMD has an issue, you get stuck pixels (either stuck on or stuck off). I, personally, know of no way to clean it besides sending it to a facility that can take the light engine apart...which normally means a trip to Barco.

[Marco Giustini]

Ok, we know the issue is NOT on the screen or the porthole glass or the lens.
if you are familiar with the task, you can move the fold mirror a bit - the last mirror before the prism - while looking at the screen. If the blotch moves with the mirror, the issue is BEFORE the mirror. If it doesn't move, the issue is AFTER the mirror (engine).

Remember that mirror must be re-aligned at the end - and you might want to lower the lamp power while testing to avoid potential damage to the DMD gaskets.

I still advise to do all these tests using a full container macro ? You're looking at half of the DMDs in Scope!

[Caleb Williams]

If the light engine was handled recently, this could be the result of a fingerprint on the prism.

Different projector, but we had a CP2000ZX with a chipped integrator rod that had a very similar presentation to this, but was more noticeable on red than other colors. If it was the DMD, as Steve mentioned, I would expect to see sharper edges and individual pixels on/off and not such a subtle impact on image. There could also be contamination between the fold mirror and the light engine. The older Christie's will sometimes have moths or other bugs that find their way in there and die and cause weird subtle artifacts like this.

[Phil Ranucci]

We has a Christie CP2220 that had a similar blotch. Called our service company and he cleaned the prism. He said it was oil / grease that had leaked from a cooling fan.