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Discussion Starter · #1 ·
Newbie and first time poster. I have searched for two days and can't find a thread that is any help, so if I'm repeating a old problem please excuse me. I have a HD72 that has worked perfect for years and two weeks ago it started have a color distortion problem. The colors would change has if I had a bad signal from the cable box then sometimes good to black and white then back to a perfect picture only after it has been running for an hour to hour and half. I have installed some new stuff about two week ago also. New Denon avr-590, new HDMI cable from the Denon to the projector and a new digital comcast box.

The problem happens with cable TV or PS3. I also hooked the PS3 straight to the back of the projector, same problem. Yesterday I was watching a movie and the problem came up near the end of the movie so I decided to finish the movie but it got so bad the projector went blank and the red lamp light is on. Is this a lamp going bad or is this possible another problem?
 

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Definitely NOT the lamp. The lamp will NEVER be the cause of any problem like that. It puts out light, period. Now....


This is a indication of a problem with the color wheel. You said something about a "screech", that is typical of color wheel bearings about to fail. It may also be that the opto-sensor near the color wheel is dusty and not allowing proper operation. The projector will see this as an error and shut down.


Opening the projector and using some canned air around the color wheel (when the projector is cold) may help that situation. If it doesn't then the next step is either repair or replacement. If all it needs is a new color wheel, fine. Those don't cost that much and Optoma will sell it to you, you just have to willing to perform the "surgery". But there is always a chance that it isn't the color wheel, if so, then it is definitely time to replace the projector.
 

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Discussion Starter · #3 ·
I cleaned the inside of the projector last night with canned air but I stayed away from the color wheel. where is the opto-sensor located? I'm thinking it may be the sensor just lower left of the wheel. I will take it apart again tonight and try cleaning that area better. Thanks for the advise.
 

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Be REAL careful with that canned air. A blast in the wrong direction can force dust into the imaging chamber, onto the optics and imaging device. Once on there, the ONLY way to get at it is to open the chamber for cleaning. To attempt to clean the chamber from the outside is like trying to vacuum your car through a small gap in a window.


The sensor will be in the direct vicinity of the color wheel.
 

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Discussion Starter · #5 ·
Sheridan1952

Thank you very much. I pulled the color wheel out and the opto-sensor off the side of the wheel, cleaned them both and ran the projector five hours last night with out a problem. I have been lurking on the website for a long time and I can't get over how helpful you guy's are. Thanks again.



Mark
 

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Doesn't it feel great when your labors pan out? Nothing like success!! Glad we were able to help. You should also feel a sense of relief that the color wheel was not damaged while it was being handled. Those are very fragile and easily broken.


Come back anytime.
 

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HI,


I think I'm having the same problem but with slightly different symptoms. When the projector is set to RGB it's all green and on YCbCr it's a bit washed out, with the clours having almost a corona round them.


Before I take the thing apart to clean it, does this sound like the same problem as Mark was having?
 

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I don't think so. What make/model is it? Are the colors correct in YCbCr (otherwise known as Component) mode?


If you have a DLP projector, I'm thinking the optics are dirty and need cleaning. Most likely, the color wheel has a film on it that is diffusing the light. A lamp that is old and weak can also cause washed out colors.


Post more info so we can help you better.

Quote:
Originally Posted by Robert TK /forum/post/18383169


HI,


I think I'm having the same problem but with slightly different symptoms. When the projector is set to RGB it's all green and on YCbCr it's a bit washed out, with the clours having almost a corona round them.


Before I take the thing apart to clean it, does this sound like the same problem as Mark was having?
 

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Thanks for replying ... I'll try to give you a bit more,


It's the same projector, an Optoma Themescene, although mine is the HD72i model.


When it powers up there's a small grinding noise for a second then everything comes on as normal albeit all green, including the menu, welcome screen etc.


It's not the cable as it's connected to a PC via DVI and a PS3 via HDMI and both sources have the same problems ... green in RGB or when I switch it to YCbCr in the menu the colours look, well rough, and as I say they have almost a corona around them.


It's hard to describe but if there was blue logo, it'd have a rough blue-ish ring around it that increases or decreases as I play with the colour, brightness or contrast settings.


I downloaded a colour chart, put it on a memory stick and displayed in via the playstation. The colours all look a bit dull, with the reds appearing almost brown and no amount of tweaking with the settings is helping.
 

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First, that grinding noise is the color wheel. It will fail eventually. That you're getting the colors change when you go from RGB to YCbCr is odd, the inputs you're using are independent of those settings. RGB and YCbCr are for signals coming in the VGA or Computer input, not HDMI.


How many hours do you have on the lamp? Has the projector been maintained, cleaned periodically? Can you look inside and see the condition of the color wheel? We're looking for obvious, easy fixes. A lamp that is well past it's prime will affect the image, the colors will be muted and dull and the contrast will suffer. A color wheel that is coated with dust and film will also affect the image similarly.


Beyond these, the next most likely cause is a failing image processor. If that's the case, it's time for a new projector.
 

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Hi all.


I'm having the shifting color problem followed by a bulb shutdown and a failed lamp light. Power cycling the projector solves the problem for a short time but it returns. I'm going to tackle cleaning the color wheel/sensor (as well as the unit as a whole). Does anyone have any photos or diagrams of where things are located on the inside? I've already replaced the lamp driver as part of my troubleshooting but apparently need to try something else since it's still have issues.


Thanks,


Sean..
 

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Quote:
Originally Posted by Sheridan1952 /forum/post/18385148


First, that grinding noise is the color wheel. It will fail eventually. That you're getting the colors change when you go from RGB to YCbCr is odd, the inputs you're using are independent of those settings. RGB and YCbCr are for signals coming in the VGA or Computer input, not HDMI.


How many hours do you have on the lamp? Has the projector been maintained, cleaned periodically? Can you look inside and see the condition of the color wheel? We're looking for obvious, easy fixes. A lamp that is well past it's prime will affect the image, the colors will be muted and dull and the contrast will suffer. A color wheel that is coated with dust and film will also affect the image similarly.


Beyond these, the next most likely cause is a failing image processor. If that's the case, it's time for a new projector.

This is incorrect. Green indicates a color mismatch, on all input types. If the pj is expecting YCbCr and you send it RGB(setting on the PS3) there will be a color mismatch. Likewise if you send set your source to output YCbCr and the pj is expecting RGB. One will show a pick tint, the other will be green. Opomas are particularly problematic in this regard, I had an HD65 that would show a mismatch(green) over HDMI if I set the output to RGB and the pj to force accepting a RGB input.


The "rough" looking image is a puzzle though..as is the dull looking color. What do you have your pj set to accept, YCbCr, RGB, or Auto?
 

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Negative. He said his Menu was also affected. An input mismatch will not affect the Menu.

Quote:
Originally Posted by novasol /forum/post/18509045


This is incorrect. Green indicates a color mismatch, on all input types. If the pj is expecting YCbCr and you send it RGB(setting on the PS3) there will be a color mismatch. Likewise if you send set your source to output YCbCr and the pj is expecting RGB. One will show a pick tint, the other will be green. Opomas are particularly problematic in this regard, I had an HD65 that would show a mismatch(green) over HDMI if I set the output to RGB and the pj to force accepting a RGB input.


The "rough" looking image is a puzzle though..as is the dull looking color. What do you have your pj set to accept, YCbCr, RGB, or Auto?
 

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Quote:
Originally Posted by Sheridan1952 /forum/post/18509299


Negative. He said his Menu was also affected. An input mismatch will not affect the Menu.

You're right..though not about what I corrected
 

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I know this is an old subject and I must apologize to all the DIY experts here, but I think I may have a color wheel problem with my Optoma EP753 pj (yes, I know it's old!) Just recently the colors are starting to "flash" green and red and outlining images on the screen and then going to black and white for a bit then to an almost negative appearance. This started last night and then today the pj just shut down. I let it cool completely and after tirelessly googling I think the problem is the color wheel. I took the bulb out tonight and gently blew out some dust from inside the pj and then put the whole thing back together and it worked great for about 15 minutes then started the flickering stuff again. I shut down the pj and that is where I am at now. Here are some additional details:


The bulb is relatively brand new with maybe 200-300 hours on it.

I do not have the pj mounted to the ceiling and there is sufficient air flow around the unit.

I do have the pj pointing down at a pretty serious downward angle in order to throw the picture at my screen with keystone correction. (already working on an alternative setup)

Lastly, I am absolutely a NOVICE at any type of repairs, but more than willing to do them with some guidance, if anyone is willing.

Thanks in advance for any help!!
 

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No, that's not the color wheel. There is no way the color wheel can give any sort of colored outline on the images, nor can it make the look negative.


Your problem is a failing image processor, not an economically repairable problem. The entire main board would have to be replaced at a cost of about $500 for the assembly.
 

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You think so? My problem sounds an awful lot like Mark_Lars though. I did fail to mention that I am also getting a new whirring sound from the pj as well. When I did a brief cleaning inside the pj the image improved for awhile. It will go from flickering to perfect and then back again.
 

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I suppose it's possible, but some of those image problems you reported just don't sound like a color wheel issue. Unless instability in the color wheel sensing is causing a problem in the processor. Hard to say.


You could try cleaning the sensor next to the wheel. But the color wheel making noise is an indication of eventual failure of the bearings, at which time, the projector will shut down. It doesn't look like the color wheel is available separately from the optical engine, which looks to have a cost of about $600 - $700. So I would say do what you can but plan on replacing it.
 

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Thanks for the info...any suggestions on where I might get some easy to understand instructions on how to safely attempt to clean the color wheel?
 
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