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Discussion Starter · #1 ·
Have had problem with my image becoming fuzzier over the past few weeks. Repair man was here today and it turns out the green and blue tubes have mottling over the phosphors. These tubes only have 1600 hours on them. What would cause this? Tube defect, overdriving, etc?

Bill
 

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Say Bill


Pull up a white field test pattern and set H Size to 95; if the mottling is much smaller than that pattern then the unit was maybe mounted too far from the screen priorly, and maybe driven too hard, a common installation blunder.
 

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Discussion Starter · #3 ·
The tubes were new, the unit has not been moved, about 95% of the tube surface is being used. The mottling is diffuse over the entire surface area, not concentrated at any particular point. It can even be seen outside of the 16:9 area, and I watch very little 4:3.Am using the unit on a 10 ft. diagonal screen 1.3 gain screen but not a overly bright levels.

Bill
 

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Any chance that there could be contamination in the coupling fluid?


Chip S.
 

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Discussion Starter · #5 ·
No. The repair person said they are defects in the phosphors. I looked last night and the mottling is over the entire area of the tube, not just in the 16:9 area. Also see some off to the edges where the beam never goes.

Everyone with new or rebuilt tubes should go to their projectors, turn down the contrast almost to zero and look to see if they have the same problem. It causes a fuzziness in the image.

Bill
 

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I have a pile of used, burned, worn and generally fried tubes here but all look perfect within the unused portion of the phosphor. I would look into this further before you condem the tubes. Perhaps bad/ defective c-elements. Who was the tech that said it was the phosphors that had gone bad?


Chip S.
 

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Discussion Starter · #7 ·
The tech was from the company I purchased the unit from. You have to turn down the contrast almost to 0 to see the mottling of the phosphors. The result is a decrease in the the sharpness of the projected image.
 

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Guys!


New Matsushita tubes would be warrantied for 90 days, VDC rebuilts for a year; how long since you bought the unit?
 

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Get a second opinion, it sounds too far fetched and too much like the old " You need a new transmission " line. Holy cow, if this is right, then every 9500 is a ticking time bomb, just waiting to explode for a HUGE repair bill which could recur at any time !
 

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Explain "mottling" please. Describe exactly what you're seeing. I've never seen phosphers magically "go bad" except in the normal manner of burn, etc. Sounds to me like something else is going on ("C" element, glycol, electronics,etc).
 
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