Flickering colours on a DLP projector after warm up.
I came across this issue with an old Optoma HD800X DLP projector purchased used of ebay. If your DLP projector is aging and has a colour wheel you may eventually run into this problem.
After a 15 minute warm up period, the colour starts to flicker. You can hear strange noises from the projector, eventually the flickering stops and you are looking at a purple/green image all the colours are wrong.
When the problem is just starting to appear you may also see a solarised picture (one with abrupt rather than smooth colour transitions) This can be temporarily fixed by adjusting the colour wheel index in the service page.
Here is the culprit:
This is a picture of the sensor board that looks at the shaft of the colour wheel. It detects a bit of back tape so the projector knows where the wheel is. Air is moving in this area so dust build-up is inevitable.
http://www.mediafire.com/convkey/4b8...0db1mftz6g.jpg
After blowing off the dust it looks like this:
http://www.mediafire.com/convkey/5d8...r93xrr0k6g.jpg
What happens is this:
It is extremely bright in this location and the dust reflects some of light into the sensor blinding it. It can't see the tape on the shaft clearly.
As the projector heats up the sensor loses its sensitivity and at some temperature (mine does this at 53C) it just can't see it any more and becomes intermittent. This causes the PJ colour wheel servo to lose lock and to start to hunt and you see flickering and hear strange noises from the PJ.
If you do a search you will find various remedies, anything that reduces the temperature will work for a while but will ultimately fail as the dust build-continues and temperature rises in Summer.
One good work-around for emergencies is to run the PJ in high altitude mode, this increases the fan speed on mine, so runs cooler but actually accelerates dust ingress.
All that you really need to do is just clean this part.
No need to extensively dismantle your projector.
No needs to clean (possibly damage) or replace (£200+) the colour wheel.
No need risk blowing dust into your optical path.
Just find and clean this bit.
Hope this helps
Peter.
