I have a 7 inch lcd. I removed the AG layer and I have it mounted on a test bench so the light passes through the viewing side where the AG layer was. Testing with a 150w hqi bulb at 220mm to double fresnel unsplit and then 1.5 inches to lcd. I didnt have a fan on the lcd or anywhere but I was only leaving the light on for 5 minutes max at a time. After about the 3rd test the lcd starting showing gosting lines and then worse complete signal break up. To make a long story short it is overheating of the lcd screen itself.

So obviously I will put a big 12cm fan on it from now on to avoid this but I am still concerned about 2 things.

1. Is it possible I have an lcd that is far to sensitive to heat and will cause problems once the build is done rendering it impossible for projector use?

2. Does the fact that I'm sending light through the viewing side make the lcd more sensitive and therefore I should try to put light through the designed side?

The simple answer is that light isn't just light. Even a resular incandesent light bulb gets really hot they are only something like 2% efficent most of the rest is heat MH are closer to 10% efficiency but still a lot of heat install heat shield and fans and it will be alright

efficiency

I tried taking some photos with a digital camera using the MH 400 and i got streaks on the lcd of the camera. Looks like heavy interference. I thought the interference is from the bulb making some kind of flicker not visible to human eyes then someone suggested perhaps the ballast is putting out EMI or electro magnetic interference. How can I shield the ballast from this using a aluminium box design?

It's probably the CCD being washed out by so much light. The EMI from a ballast shouldn't be enough to affect a camera.

The problem was simply overheating lcd. I now have a 12cm fan directly behind the arc sucking heat out and a 12cm fan blowing air past the lcd . While its a fairly open setup on a test bench and no dust filter installed I think this will work. The noise however is a little distracting. I think a better setup would be to use one or even 2 real IR filters and using 2 small 80mm fans instead in the same positions.