I've got a problem with damaged Toshiba TLP-550 projector. It was supposed to need only lamp replacement, but I checked it using a small 35W halogen lamp, and there is a permanent red flare in the screen, like in this picture:
startup logo:
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blue control screen from test dvd, should be all blue, except this small info in the upper left corner:
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This red bloch stays solid, regardless of video signal being displayed. Besides that projector is fully operational, and it looks to me like a mechanical or thermal damage, maybe the polarizer, or the LCD itself? I would be grateful for any comments.
Maybe someone owns a service manual for this projector?
As the unit is intended to use a super bright plasma discharge lamp, then a low wattage halogen lamp will be no use at all, and you are probably just seeing dust or minor anomalies in the optical path. Bear in mind also, that the spectral composition of the light is rather different between plasma lamps and incandescent halogen lamps. With the correct lamp fitted, it will probably look fine.
I can see why you would want to check it this way, as the cost of a replacement lamp is ball-breakingly high, but if you're confident that this is all that's required, and there is no problem with the ballast unit ( high voltage generator for lamp start and run ), then you probably have no other option but to go for it, and hope for the best. I'm actually quite surprised though, that you've managed to get this far with testing, as normally, if any problem is detected with the lamp, the system control puts the unit into a full shutdown.
Well, I considered that, but I doubt it would look good with a "real" discharge lamp. This broken LCD or polariser (or whatever is broken) will still pass this red light, as there is a lot of red wavelenght in the spectrum of a discharge lamp. The problem is that the screen is not uniform. Narrow upper part is perfectly fine, but it's getting bad towards left lower corner. This does not depend on the bulb placement, or the angle of the light beam that I direct into the projector optics. These red patterns are fixed to the same position, so it's not an optical phenomenon in the lenses or whatever, it really exists somewhere in the light path.
It's neither a permanent red-tinted burn into any optical piece, as when I send a white test screen to the projector, there is almost uniform white projection, so all three light channels can fully "open", but for some reason the red channel canno't fully "close" in this irregular area, it leaks it like you can see in the pictures. And there is that darker spot in the middle of red bloch, looks like a centre of the damage, maybe this spot was overheated? That's just my guess, so I'm looking for advices from more experienced people, maybe it's some typical malfunction.
I "cheated" the projector, wiring a standard 400W MH bulb (big one, so it was outside the projector) to the internal ballast, and supressing the security switch. All circuits seem to be fine, lamp was working OK, no problems with ballast or any other functionality, except this red light blotching the major part of the screen.
Can you find someone with a similar projector and borrow the correct lamp for testing? In a pinch you could buy a new lamp, then sell it if it doesn't fix the problem.
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