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  #1  
Old 07-02-2018, 01:16 AM
cheddarbob cheddarbob is offline
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CRT Projector Project (I may be Crazy)

I know I am a bit crazy for taking on this project, but with out a little crazy, there is no fun.

So here it is

I Acquired a Toshiba 57H83 TV, for the low low price of Free... I didn't need a TV, i have a small living room with a 40" LCD on the wall and a 37" LCD in the bedroom. My old house has what we call the "Bonus Room", a carport that was enclosed without permits some 40 years ago, Would be a great media room for this TV, but I already have it as a media room with a 100" screen on the wall and an LCD projector on the ceiling.

So enough Back story, Here is the status and the idea:
I want to turn the light box from this Toshiba TV into an overhead CRT projector to display on my 100" screen.

So far, I have removed all the electronics from the cabinet of the TV, so now I have the N3PSP chassis sitting on the table, able to procect a 75" image on the ceiling, and got it focused to a degree.

The problems

Need to flatten out the mounting, or make the angle adjustable for the red and blue CRTs, need to move the CRT mounting plate to the front of the chassis to make it more ceiling mount friendly, and possible do a vertical flip, to get a better angle to the screen when it is mounted with less modifications.

Any ideas would be greatly appreciated, and of course, I will get some pictures attached as soon as I can.
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  #2  
Old 07-02-2018, 01:50 AM
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MIPS MIPS is offline
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I did this once with a hitachi cabinet and posted in one of the other subforums. The results were.......unimpressive.

RPTV sets are really designed for their specific task and likewise their luminous output is only so much for close-range rear projection. Likewise the lenses are ground and adjustable for distances no more than five feet away with little to no adjustment for keystone.

In other words: you can do it but it is going to be very unimpressive and dim compared to a true FPTV unit. I ended up abandoning it and getting a proper setup.
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  #3  
Old 07-02-2018, 02:37 AM
cheddarbob cheddarbob is offline
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that was my initial thought, but... I am able to focus the image on each CRT at a distance needed for greater than my screen size, maybe a 120"to 130" image. The convergence adjustments in the service menu allow me to adjust the geometry enough to account for keystone (enough atleast to produce a usable image on my kitchen ceiling. The throw distance is fairly short, like a 0.7:1 (from what i calculated) so that does make up for the lower lumens along with my 1.3:1 gain screen, I should be good in my almost blacked out room. Distance to the screen should be about 5'6", was able to focus each crt to a distance of about 7.5 feet and there was still room.. This light box was designed as a pretty universal unit for many different sets in the line.

I think the saving grace of this project is, i am dealing with the last of the CRT RPTV units, so this is about as good as it could get i think.

My biggest issue is modifying the CRT mount to clean up the convergence, the Red and Blue are at a but too much of an angle to get the convergence on my 100" screen.

That being said, Even if I never get satisfactory results, the project is still fun and to be able to say I did it, is enough for me. free is free, and I am a broke nerd, so I will take what i can get.

Last edited by cheddarbob; 07-02-2018 at 02:43 AM.
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Old 07-02-2018, 11:15 AM
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old_tv_nut old_tv_nut is offline
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This sounds like an entertaining project as long as you aren't expecting perfection. RPTV lenses may have a non-spherical element that is optimum only at the designed throw distance, so when you focus at a different distance, the result will not be so sharp; but you can have fun experimenting.
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Old 07-02-2018, 01:24 PM
cheddarbob cheddarbob is offline
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Entertaining is my goal, I am not going to extreme in my change of screen size i think, the light box is used on the entire range of this model 51" to 65", and possibly smaller too.

The fun has already started, gonna try and get some progress today, and some pictures.
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Old 07-02-2018, 07:01 PM
cheddarbob cheddarbob is offline
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ok, got some pictures, full daylight, image is halfway decent at night with the overhead light on, should be bright enough on the screen in the home theater, i have that room damn near blacked out already.

But do want suggestions with any ideas on how to modify the CRT mount for the red and blue to get a better grasp on the convergence.
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Old 07-03-2018, 12:49 AM
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Do they have no physical angle adjustment? Is that what you're asking? You might need to make a whole new mount for the red and blue, something easily adjustable. You might be able to hinge the inner side of each, and attach an adjusting screw on the outer side to lift it up or down.
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Old 07-03-2018, 01:11 AM
cheddarbob cheddarbob is offline
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That is exactly what I am asking, if anyone has done this and might have some insight, was thinking exactly that, hinged on the inside, and some adjustment screws on the outside, just trying to work it out to make it happen.
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Old 07-03-2018, 07:39 PM
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MIPS MIPS is offline
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The way I worked around the coarse convergence was that the innermost tube was fixed to the frame while the outer two were mounted with spring loaded bolts on the outside edges and two threaded adjustment knobs on the inside edges. Another two knobs would tilt the frame up and down on a welded-in piano hinge but I never got the keystone issue figured out. I found that for the short time that my STK convergence amplifiers were behaving it worked very well.


http://i11.photobucket.com/albums/a1...y/IMG_4525.jpg


http://i11.photobucket.com/albums/a1...t/IMG_5247.jpg


http://i11.photobucket.com/albums/a1...t/IMG_5277.jpg

Last edited by MIPS; 07-03-2018 at 07:44 PM.
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  #10  
Old 07-03-2018, 10:24 PM
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dishdude dishdude is offline
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Looks good!
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  #11  
Old 07-03-2018, 10:42 PM
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mr_rye89 mr_rye89 is offline
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you might look at some lenses for CRT front projectors on epay. Too bad that I trashed a good set off of my Electrohome ECP (It caught on fire )
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  #12  
Old 07-03-2018, 10:50 PM
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Quote:
Originally Posted by mr_rye89 View Post
you might look at some lenses for CRT front projectors on epay. Too bad that I trashed a good set off of my Electrohome ECP (It caught on fire )
Or just watch everything in a mirror
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Old 07-04-2018, 01:16 AM
cheddarbob cheddarbob is offline
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I like that idea for the course adjustments, I was hoping to keep the inside edges basically down, and be able to adjust down the outside edges, to try and keep all three tubes as close to the same distance as possible.

Front projection lenses might not be a bad idea, but that will then make for a longer throw, and it could make my light levels less efficient, Figure with the lower light output, I would benefit from the short throw distance.

No need for a mirror, as on the RPTV it bounces off a mirror to project to the back of the screen, so in a front projection setup, the mirror is not needed.

All ideas are welcome, and I know i will crack into something soon.
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Old 07-05-2018, 06:54 PM
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MadMan MadMan is offline
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Looks like MIPS did a damn good job on his setup. Bunch of threaded rods with locking nuts and screw-on knobs, spring-loaded bolts acting as hinges?

Ey... that's pretty gud.
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  #15  
Old 07-06-2018, 03:10 AM
cheddarbob cheddarbob is offline
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Quote:
Originally Posted by MadMan View Post
Looks like MIPS did a damn good job on his setup. Bunch of threaded rods with locking nuts and screw-on knobs, spring-loaded bolts acting as hinges?

Ey... that's pretty gud.
I am absolutely stealing that idea with the springs, I love it, should do the job on the inside edges, gonna use my dremel and cut off the mounting ears on the outside, and rig something up with with some angle aluminum to make the adjustments.
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