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Discussion Starter #1
Hi,

I have a NEC 9PG Plus I purchase a little more then a year ago. I was planning on building my HT then, but money went into other home remodeling and my HT project was put on hold. The projector has 6900 hours on it. I will probably have someone install and set it up for me, but I need to know if it would be best to have it re-tubed now before it is installed? I was told that it is recommended replacing the crts at about 8000 hours, but do they actually get a lot more hours then this with good care? I have no idea of what kind of PQ it currently gets and if it suffers from any decrease in contrast loss, which I heard happens as crts get a lot of hours on them. Once they install it, does it need to be taken back down to re-tube it? And if they can re-tube it without taking it down, does it then need a complete recalibration?


Thanks for any help you can provide me :).


Best Regards,

Don
 

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Don,


the timelife of the tubes is heavily affected by the set-up that you did on your pj. Sometimes it is possible to see tubes with 5000 hours clearly burned, and in some other cases it is possible to see pjs with more than 8000 hours in acceptable conditions. Normally it depends upon the internal adjustments (specially concerning the G2), the contrast level normally used, and the screen size too...


The best suggestion, in my opinion, is to check out the blu and green tubes, looking direclty into the lenses with a small light (when the pj is turned off), or better, to dismount the lenses and look directly on the CRT surface. You can also check them out getting a bigger raster (== enlarging the image, with the "size" command at maximum, taking care to keep the whole image inside the CRT surfaces!) and, turning on only one tube once, look at the borders of the image (specially using a totally white image). If you clearly notice "darker" borders all around the image, like a rectangle, the tube is burned...


A tube burn will cause a lot of problems obtaining a good and corrected grey scale and grey tracking and, in most of the cases, a loss of detail and resolution.


Surely it's recommended to replace the burned tubes on the pj before to install it, specially if it will be placed on the ceiling, for the fact that the future replacement will require that you dismount it... and surely a complete re-alignment will be required (concerning the astig, the internal color set-up and, obviously, the geometry/convergence from scratch...)


it's just the my opinion


Romano
 

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Discussion Starter #3
Thanks Romano,

After purchasing this projector I took it into a place here in the Phoenix area that specializes in repairing and installing these and it all checked out good with no burn-in.


Best Regards,

Don
 

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If it checked out ok then it doesn't appear that you need to replace the tubes. If you are unsure, project a white screen and see if you can see any color variation on the image. If it is burned or non uniformly worn, you will see a 4:3 pattern in the center that is likely pinker than the white around the edges. Once you see this, you will also see it in your images. (I am assuming you have it setup on the floor where you can run test images through it.) As to brightness, you are the judge of that based on the size of the screen you have and the ability to control light in the room. Your contrast and brightness controls should be down in the 50% range. Since there are no reported burns, it appears the unit was probably well cared for and not abused in some conference room.


.Doyle
 
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