H31 has a new color problem after blowing out dust

You probably blew away a segment of your color wheel. Easy to tell by feeling the projector during running. If the wheel is missing a segment, it will be out of balance and impart a vibration to the projector.

The bulb will NEVER cause any problem like that. Only a change in brightness/contrast.

You didn't say, but you never blast air into a hot projector.

I had assumed you used a can of compressed air. Under normal circumstances, it should not be possible to dislodge a segment. They are fixed with a strong adhesive. However, over time and heat, the bond can soften. I've seen it. If a segment has come off, but is still intact, it can sometimes be reattached. This does require that the color wheel be removed. If the segment is no good, then a it would have to be replaced, assuming that parts are available.

But we are jumping to a conclusion here. The first step would be to verify the initial diagnosis. If it ISN"T the wheel, then you have other, far more serious problems. Problems that most likely are unrepairable as it would be an electronics failure.

BTW, you didn't say whether the dust had gone away, but I would bet that it hadn't. Dust like that is usually in the imaging chamber which is "sealed" and cannot be cleaned with air blasted into the sides. The projector would have to be opened for service.

So much for my assumptions. Since it is normal on startup, that eliminates the color wheel, as you reasoned. That leaves the more serious possibilities. I have not seen a projector do what you're describing, but I can't think of anything else it could be besides a component problem.

bergie33 - was it easy taking apart the h31. I seem to have a flickering peice of dust of some sort on my screen that moves.

Possible the dust blob got onto the color wheel sensor and was causing it to spin at the wrong speed after the intial startup when it tried to sync?

It's fine to clean the color wheel, but any dust visible in the image will NOT be there. It will be in the imaging chamber behind the lens. Think about it, the color wheel is spinning at a very fast clip. How is dust going to appear as a spot? Besides, the color wheel is nowhere near the plane of focus.