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Discussion Starter · #1 ·
I recently replaced the Green CRT with usage burn of my NEC 9PG+ with a new one. I took some pictures to document all the steps necessary.

Replacing the CRT is just a small part of the process, the harder part is to setup and realign all the CRT's again.


WARNING: A CRT projector is capable of producing very high voltage. Please take all necessary precautions or better yet, hire an experienced technician to perform them for you.

http://photos.yahoo.com/bc/avictc/sl...src=ph&.view=t


PS. Anyone interested in the G CRT with usage wear?
 

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Hi there,


Thanks for the pictures and explanations. I am sure that there are many different ways of exchanging tubes (the physical part of it) in CRT projectors and you have demonstrated the method that worked best for you. I will one day partake in changing the green in my PG-9200 as well! My new green CRT is sitting in its box waiting to be used. How does the new tube focus? Did you have to adjust the CPC magnets?


I just wanted to comment on one thing. It looks to me that the usage of phosphor on the CRT face is no where near being maximized...You could probably increase your amplitude, both horizontal and vertical, to make use of more phosphor therefore increasing light output and resolution. This would require moving your projector closer to the screen as well. It looks like you have hardly any wear on the red and blue, so now would be a good time to try it because you have replaced the green. You might notice the worn area to non worn transition area since the phosphors do show some wear but I would give it a try...just a suggestion.


I have attached a picture of the CRTs in my PG-9200 for you to take a look at.
 

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Discussion Starter · #3 ·
Thanks for the comments.


You are right, since I replaced the Green CRT I can now project a larger image compared to my current 72" wide screen. I can now go 84 or larger. I was using a 72" wide to hide the uneven wear on the green tube.


The focus on the new tube is excellent. Even my wife noticed a sharper focus after a replaced the tube. I used the CPC magnets to sharpen the dot size of the green and then refocus the lenses.
 

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Bradad,


RE-attach:)picture does not work,



thanks-


tommy
 

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Chris, is your projector at the recommended throw distance? Some guys have the projector closer than recommended, therefore projecting a smaller image than what is required allowing you to increase the picture amplitude to use more of the phosphor. There could be other reasons that the worn area is small though. There are pots that need adjustment for raster sizing vertical and horizontal which require a multimeter to measure voltage output so you do not exceed spec. Someone else can correct me if I'm wrong about this...I don't know why the picture didn't work but I'll try it again.


Brad
 

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Sorry, I can't get the image up. I've done it before so maybe there is something up with the server? I can email it to you if you like.
 

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Chris,

Good presentation. Thanks. I try to tell everyone that your image is only as good as your green tube, be it set up or phosphor wear.


In your case you probably could have went longer if you could control the white balance and live with some pink.


As long as you dont move the red and blue raster this will give you a much better image, any more ware on the red and blue it would show up on a wider screen, it probably does show but not in a bad way.


When ever you can replace the complete set if you have some bad burn, the red is the last to show in most cases, if you can catch it just right you can get by with just the green and blue being replaced.


A trick on the CPCs is to mark the top of the cluster and re-install the same way, this will get you close with a starting point, the other is to start the focus yoke up tight to the deflection yoke then slide it back for best overall focus, in most cases it will be up close to the deflection yoke but I have seen others be much better moving it back a bit. Good job, anytime the wife says theres an improvement you just justified spending the money. Doug
 

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Quote:
Originally posted by Bradad
Sorry, I can't get the image up. I've done it before so maybe there is something up with the server? I can email it to you if you like.


Yes Bradad please send it.

[email protected]


thanks-


tommy
 

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In the IE address bar, when you get a whitepage showing up instead of the picture, theres always this at the end of the addres: &fullpage=1

just erase it and click enter and "voila" you get the image


Ciao


Benoit
 

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Discussion Starter · #10 ·
Brad,


When I purchased the projector, it already have the usage burn on the G tube. It was used on a convention center before and the projector was placed quite a distance from the screen. That's why I set the image to within the burn area initially.

Now that's the green is replaced, and although the R and B have some very minor wear, I can maximize the phospor area and throw a larger image. Still convincing the wife that we need a larger screen, though. ;)


Doug,


I actually was using the projector for more than two years aleady with the old tubes. I just happen to chance upon a new Green tube and couldn't let is pass.


Thanks,

Chris
 

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What a great presentation. I would only add that if one wants to be able to put the tube magnetics on a little easier, its totally acceptable and quite easy to unplug all the wires and remove the tube with all the tube magnetics still on the tube. Leaving the neck board in the machine is the only thing I leave when replacing a crt. A note also about the red and blue crt's in a PG (and I think XG NEC) they have a screw receptacle on the bottom where the outside rod attatches that sets into the crt frame, so its a tiny bit more difficult to get the red or blue crt's back into the frame.

Again, a VERY good presentation, and one that should make it a lot easier for anyone to tackle this job.
 

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Chirs,


I hear you and you did absolutely the right thing setting up the picture in the worn area. Now that you have the new green in there, you can try maxxing it out.


Thanks again, now go enjoy that beast of yours! :D


Brad
 

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Quote:
You are right, since I replaced the Green CRT I can now project a larger image compared to my current 72" wide screen. I can now go 84 or larger. I was using a 72" wide to hide the uneven wear on the green tube.
Honestly, I wouldn't go much larger than 80" wide, (maybe 84" max). These PG projectors are great machines, but still only have 7" tubes. They operate best between 72" and 80" wide, and give you a stellar image!


Enjoy,
 

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Discussion Starter · #14 ·
Quote:
Originally posted by DMan



Honestly, I wouldn't go much larger than 80" wide, (maybe 84" max). These PG projectors are great machines, but still only have 7" tubes. They operate best between 72" and 80" wide, and give you a stellar image!


Enjoy,
Good point! I'll keep this in mind when deciding whether to get a bigger screen.

Thanks,

Chris
 

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Discussion Starter · #15 ·
Just an update.


Instead of getting a larger screen, just decided to move the CRT closer to the screen to maximize the phospor area. Amplitude is now about 96% and there is a considerable improvement in projected image.
 
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