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My PTAE2000 developed a faint green circle near the top-middle of the screen after less than 50 hours of use. With enormous thanks to several posts on AVforums, I diagnosed it as a dust blob. When almost fully defocusing the lens in one direction the circle changed into 3 bright green pixels each separated by 1 or 2 pixels. The defocusing also revealed lots of small dark patches throughout the screen (although these were not visible when the focus was normal).

Here's my experience of removing the circle:

1. Bought a couple of spray cans of compressed air (actually what comes out smells like a petrochemical, but the blurb on the can stated it was suitable for delicate electronics and photographic work). Cost about 10 quid each from a local electronics shop.

2. Downloaded a service manual for the PTAE2000 from www.nodevice.com (cost 10 euros), which contained details on how to almost fully disassemble the projector (didn't need to do this, fortunately -- see below).

3. Removed the top cover and lamp unit as per instructions in the user manual for changing the lamp.

4. Removed the upper case by unscrewing 8 screws, and stood the projector on its back panel so that I could spray into it without tilting the air can (I found that liquid didn't come out of the air can until it was it was almost horizontal, but I wanted to make sure that the can stayed almost vertical throughout the cleaning procedure in order to minimise this possibility).

5. The position of the LCDs is obvious from the three wide connecting ribbons (this arrangement probably applies to most projectors). I had intended to remove the "A-P.C. Board" as per the instructions in the service manual, but although it is held by only a few screws, perhaps a dozen connectors would also need to be removed. After unclipping the first 2 I decided that this was going to be a bit difficult (they were very tight, and I didn’t want to damage anything in case I had to send the projector back to the manufacturer under warrantee), so instead I sprayed the air (via the thin plastic pipe that came with the can) through the gap between the ribbons and the PCB in the general direction of each PCD panel.

6. Upon reassembly and testing the green circle was still there, as were all the dark patches. Oh dear.

7. Decided to give it one more go before contacting Panasonic, and this time I ensured when spraying that the end of the plastic pipe was almost as deep below the PCB board as the top edge of each LCD panel. I wasn’t 100% sure that I could see where each LCD panel was, but I tried to spray both sides of each of them and also through a copy of holes in the metal box covering the square area where the light beams intersect. I also sprayed into an accessible gap between the lens and LCD assemblies.

8. This time upon reassembly the green circle and all of the dark patches had disappeared.

In summary, it took about 30 minutes and no hassle of returning the projector to the shop or manufacturer (even if they did do this under warrantee) to completely remove the dust blob and also lots of other rubbish on the LCD panels.

I still don't understand why dust (or anything else that is in the light path that shouldn't be there) would appear as individual bright pixels when defocusing -- anyone have a convincing explanation?

Cheers, Peter Roberts