I have decided to build a RPTV similar to SPK's. I replaced most of my componets, I now have the EYE bulb as oposed to the MH400, a used Samsung Syncmaster 151, new PJ box, and a 53" old RPTV screen from a TV shop.

First the plans:


Here is the LCD pre strip:


Here I have the back off, so far so good:


Here is a picture of the controls. Its a self contained pull out piece so it should be easy to position:


Here is the wire going to the LCD that may need to be lengthened, anyone have any ideas besides solder and wire?

Here is a FFC that I will have to order a extension for, it is a 20 pin:

Here is the stripped panel:



Oddly enough the panel on the inside says Chi Mei M150x3 Rev: C1. The rest is coming along, I'll post pictures of the TV box once I get it all together.

Jim

Time for an update, everything is going good so far;



Here is the completed LCD setup prior placement, note the use of plexi to hold the circut boards in place.



As always, proper cooling is needed.



I am using 2 hard drive fans off of the same cord.



The semi-done PJ



Here is the front of the unit using a 53" screen.

Here you can see the placement of the ballast and the sure to change lower mirror mount.



Here is the back, I am sure that my depth is way overdone but I would rather have the adjustment room.

YOU ROCK!

Anxious to see results!

I did a real quick wife hold screen, I hold mirror and it looked good before focus adjustment, should have it finished by weeks end.

Jim ..Looking GOOD !!

So you bought your screen from a tv shop did you have any luck finding it anywhere else? I was also wondering about the mirrors that you are planing to use are they both FS mirrors if so where did you purchase them from?

I called about a dozen tv repair shops before I found one that had 2 screens, this one and a 48" one. Apparently most places just throw them away.

I am using a LL front surface mirror cut in half, one part on the inside one on the outside. For the large mirror I am using a 1/8" mirror cut to the same size as the RPTV screen, I hope to have the entire thing together later tonight.

MuHaHaHa, IT'S ALIVE!!!!!!!!!!!

I finally got it together, all that is left is finishing work and focus alignment, which hopefully I can get to on Friday.

First I mounted the mirror to peg board using liquid nails,


You need to be sure to let the glue dry.....


Here is all of the placement so far,


Here it is with the screen in place,


And the results (looks brighter in real life):


OK, now I just need to work out which mirror goes where, what angle's, PJ placement inside the box, focus, but....


IT WORKS

well done! are you sure the two PC fans are going to do the job? I have one of those in my pc and it doesnt push much air. I would go with two 80mm or two 120mm fans for proper cooling.

Wow, are all those bottles fuel for the project?

I do have a temp sensor and will keep an eye on it. Together they move 70 cfm, which isn't bad. My last PJ was only one 120mm fan.

Well done,

Can i ask what the actual screen is?

It looks like a freshnal........

Chris H

It is an actual RPTV screen. It is a piece of plexi? with groves running up and down like a fresnel but without the circles. There is also a piece of plexi for support.

Oh Ok,

Good luck, it looks great.

CH

I believe they are Fresnel lens with a long fl I bought one and cut it up. One side is a Fresnel the other side has a dispersion layer of some kind straight lines cut into it. You will be able to see the Fresnel rings. but they are vary fine and smooth. The Fresnel side faces toward the triplet and the dispersion faces out.

From what I can see it might be in backwards.

no the grooves are facing the inside, itis just very blurry and I need to adjust the positioning, thanx for the tip though

Here are the focused results:



First, I lined up the projector to get the 53" image all nice and focused before putting it back into the RPTV.



Here is a shot with the lights off



And a shot with a light on right over my head.

The shots are in focus and the image looks about 10x better, blame the shots on the camera. I am pretty happy with the results, the only problem I have noticed is that when you look at the screen, all you see is a big focused circle with the part outside it a little dimmer. I have already switched back and forth on the fresnels to no effect. Anyone have any ideas?

Jim

After re-reading this post, I will work on switching around the screen to see if it helps. Should the plexi be facing out, the grooves facing out behind the plexi? Grooves facing in towards the mirrors? Any ideas on this on one out there? By grooves I mean th estraight lines not the fresnel rings.

Jim

It's hard to tell wether the tunneling effect is due to the screen or your build. First of all, make sure your fresnals are correctly positioned. The grooves on your fresnals should be facing each other. If you are using the split configuration they should be facing the lcd. If you are using the unsplit then they should be facing each other. Once you have checked this then you can concentrate on the screen.

your rptv screen is probably to blame

might have a focal length



Mine did, from an old pioneer.

OK, quick update. The fault is in the RPTV screen, it appears to be an older one where you have to llok at the image dead on. I then took a white sheet and tried that and it looked much better. I then used a thin white blanket and am almost approaching the level of brightness I want. I can also view the image from any direction. I will work on pics later, and I am waiting for an sample of an actual rear projection cloth to see if that works better.

Jim

Does this RPTV screen look like it got some type of black tape around the edge of the screen.

Some of those old screen comes in 2 sheet and 1 is some type of focal sheet which could be seperated from front screen by unpeeling the black tape around the edge.

I had done repair where I had to seperate the sheet to clean in between becasue they would use too much window cleaner trying to clean thier TV screen and it would leak to the edge then bleed back between the 2 sheet.

Bill

There are 2 sheets of a plexi like material. One is grooved on one side, I have that facing the mirror. The other is just a clear piece of plexi(?) that I have on the outside. There was no black tape around it, I got is from a repair shop and it just ahada a plastic clip on the top and bottom. I myself built a wood frame and both pieces are sitting next to each other.

Should I go back and make sure the ends are taped together?

Jim

No I was just saying maybe try with just 1 sheet, the one on outside which have no focal on it but only if the outside have a dull looking sheet to be able to capture the image hitting on it without the sheet with groove or focal looking on it since you are already using a focal fresnel near your LCD.


Bill

One thing I always wondered about.

Using a white plexiglass or one of those paper thin white plastic sheet to cover the back of the outside RPTV screen in place of the focal sheet if it transparnet so the image have something to project on.

Just throwing some ideas but I don't know if that will work or not.

I would think a hard plastic-like sheet would project image better than a white cloth sheet.

Bill

What about the white plastic shower curtain people are using?

I'm going to try that as well, first I'll post some pics of the sheet and blanket.

Jim

Hi Jim, how is your project coming along since your last post? I am rear projecting as well so I am curious as to what material you are currently using for your screen... And whatever else you may have discovered!

G'Day Jim

Any news on ur RPTV ...?

Cheers

Don't know if this will help, but I noticed someone mentioning focal length. This made me think of a problem some people have when trying to project an image from a telescope. It happens when the telescope's projected image doesn't fully cover the area, for ex., of a frame of 35mm film when doing astrophotography. In this case, it does have to do with focal length. With telescopes, they call the problem vignetting. It's shape is circular since that's the shape of the lenses. What I don't understand is why your image is circular and not a rectangle. The solution to your problem might start with that. But I have no experience in these matters so it's just a suggestion.

uhhh, i fix a`llot of RPTVs, the fogged plastiv goes on the outside the spines out running vertica`lly, the frenel lens in the back, grooves pointing to the mirror... This is how the real ones are made, mucking with them the pics you have show it backwards.. That is none the less cool, simple fix too.

Jim, Hows your project? I have a 55" Hitachi im waiting on a transistor to arrive, if that don fix it Im gonna gut it and do a LCD inside. I already have a 15" vertical I built last year that works perfectly. Im wondering about the Screen though. The TV is 16 years old! If there is a focal length why couldnt you just project from the original distance and adjust by using the proper lens. Tell what you are doing now. I need some guidance from a voice of experience. Thanks.