A couple of months ago we started noticing a fault with our data projector (Hitachi CP-X301) which we bought maybe 5 years ago, (so it's obviously well out of warrantee). A slight yellow/green hazy circle is appearing in one area (near the upper-middle of the projection area). The yellow/green is most apparent in darker conditions, but it seems to be becoming more noticeable. It also results in a slight blurring of anything in the area of the projection area, which is noticeable even in light conditions. (The projector is inverted and attached to the ceiling, and I can get it down if needed.)
Attached are 2 photos which will hopefully show you the problem. One photo is a spreadsheet, it gets most blurry around the cell which contains “61”, and this blur is also noticeable when projecting song lyrics. The other photo shows a “X” which is caused by a shadow from room lighting (no problems with the shadow), but just above the centre of the “X”, you should see the haze.
Our lamp had done 1700 hours so I replaced it about a month ago, and that helped with brightness, but not with this haze issue.
I tried cleaning the lens (for the first time), but that didn't help either.
I've only cleaned the filter a few times with this projector, because I've just realised that unlike our previous projector which prompted us every 100 hours to clean it, this one hasn't been prompting us at all, and I see the only prompt period options are: 500, 1000, 1500 and 2000 hours, and the factory default is 2000 which we haven't yet reached! (I've now set it to 500 hours). I did clean it when I changed the lamp, though.
I don't think this issue has anything to do with the cables, because it happens on both cables (VGA for PC and RCA for DVD) and even when displaying the menu (which uses neither cable).
What's the likely cause? Dirty or damaged LCD(s) or prism lenses? "Sunburnt" LCD(s)?
How could I conclusively confirm exactly what/where the problem is. I have some experience with fixing electronic equipment, but haven't tried projectors yet.