Data Projector has big yellow blotch

  • Thread starter Thread starter Picard
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Picard

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My class' projector throws a big yellow blotch with the projected image. Is it the lamp that is starting to die?
 
you may be running into a large problem here, my dad had something similar happen to a rear projection TV, and it wasn't the lamp, it was the lense being burnt, and there is no fix for it. I might be wrong but replace the lamp and see if it goes away.
 
Just a guess but it could also be the lcd ( if it is lcd)
 
xumwun said:
Just a guess but it could also be the lcd ( if it is lcd)
Click to expand...

I read this diagnosis on a some tech-repair site.

The Purple dots indicate the filters are clogged and let dust get into the optics. You will have to Blow out the prisim block with compressed air and carefully wipe the dust particles off the LCD panels. WHATEVER you do DO not remove the three LCD panels from the block they are a royal pain to line up They can be cleaned with out removing them. If you have a yellow spot on the screen it usually means the blue LCD screen needs to be replaced. this is a more difficult job. The MOST important thing about LCD projectors is to keep the filters cleaned or they overheat spit dust and cook the panels!!
Click to expand...

I also have plenty of the blueish spots.

I think this thing needs a major service.

Question; if it is the lcd screen, how will it cost to replace?
 
Could be that the LCD or some inner equipment got too hot due to poor ventilation, or the projector getting switched off immediately after use without allowing the fan to cool it off first.

Might be cheaper (and better) in the long run just to scrap it and buy a new projector. With a new one you get a warranty, with repairs the warranty is iffy...
 
I have been through two LCD projectors over the last few years, with the same problem.

The blue channel polarizer overheats and burns a patch on the organic material.
This then shows up as a yellow blotch or blotches on the screen.

The replacement polarizers were so expensive and coupled with high replacement cost of bulbs nearing end of life, it was cheaper to get a new projector, which was usually an upgrade in brightness, resolution and performance anyway.

This is a typical problem of LCD projectors and has something to do with the wavelength of the light in the blue channel, which runs hotter. The blue polarizers always seem to go first followed by the others.

It's a toss up between cooling efficiency and fan noise. That manufacturers love low db noise levels to make the projector quieter in a domestic home theater environment, but this compromises cooling. The newer projectors are improving and hopefully LED type bulbs will catch up to similar lumen output levels at lower temperatures.

Of course you could always look at a DLP projector with its spinning colour wheel idea, as it does not suffer from the same problem. I have personally avoided this, as I can hear the high pitch "whine" of the spinning colour wheel and are one of the few who are sensitive to the visual "rainbow effect" as well. The newer DLP's are getting better with higher colour wheel speeds and more segments to reduce the "rainbow" problem.
 
Most DLP projectors dont't use colour wheels anymore, instead they a 3 dlp chip system.
 
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