DIY Rear Projection TV - Page 5

dbc105 · 13th January 2004, 12:15 PM

well I picked up 3 bad RP big screens this weekend. I have not had a chance to pull the backs and take a look but plan to do that this weekend and see what I have. I can see in the lower front of one and it has 3 CRTs pointed toward the rear at an upward angle so I am guessing that they are pointing at a mirror. it maybe that I can position the projector part where the center CRT is. rmccoll, do you have any more pics of what you built? Landers(the tv repair guy) said he had several of these things in his way so maybe I can get lenses, fresnels, etc...
David
dbc105

mbates14 · 13th January 2004, 02:25 PM

yea, thats what you should do. remove teh CRTs, and have the projector lense where the green CRT was.

If it were me, i would attempt to repair the RPTVs before I use them as projects.

I just got a 53" i found of the street, and im currently ordering a vertical deflection IC, which is $4!! thats all thats wrong with it, along with a fusable resistor. and a shorted DC supply diode.

after this, alls well.

ALSO, if one of your 3 sets has a magnovox PTV-375 chassis, I need the convergence waveform board(the one with 40 knobs).

shout at me if you find one.

karmaz · 13th January 2004, 02:33 PM

Quote:

Originally posted by Nevermore
I just found this thread on the internet, and I must say that there are to little people builing an RPTV.

I'm building one myself at the moment, and I hope to finish the damn thing before the end of the year.
I'm using a plexi glass screen, which has one satin surface (Atoglas). For as far I can tell up to now this works great if you can bring enough light to the screen. Satinized plexi has a little smaller grain, but is hard to find. What I did was ordering samples from different producers, before ordering.

For the cabinet itself, I use a two-mirror system. This allows a longer projection distance in a relative small cabinet. I found that the downside is that if the angles of the mirrors some times can give very weird images, but this is just trial and error.
At first I started out with a projection panel, but now I'm switching to a LCD projector. The image is MUCH better, and brighter and it was a real bargain.

Hi Nevermore,
I'm very interrested by your experience!
Can you give reference (12128001 ?), price, specs, resseler of your screen ?
Results of different sample ?
Any snaphot of the screen ?
Details of your box, type of mirror...

Thanx
The French guy...with the very bad English

dbc105 · 14th January 2004, 11:49 AM

mbates14, not much chance in repairing any of them, the guy I got them from repairs TVs and a lot of parts have been robbed from each one of them. But, they do have screens, lenses, mirrors, etc... That should save me a lot of time and money in the start. Question, will using a LCD monitor screen instead of a panel get the picture quality up to High Definition? I stumbled upon a projector site the other day and the guy was using a LCD monitor and a line doubler on his projector to acheive a very high quality picture. Also, how would you go about getting wide screen?
David
dbc105

dbc105 · 19th January 2004, 06:17 PM

Well I got the backs off the 3 RPTV I got. 2 of them use a single mirror to reflect the image onto the back of the screen, the third tv uses 2 mirrors, a small one down low and a large one behind the screen. One of these is a Pioneer, it looks to be the best choice. The CRT projection lenses are bolted to a metal plate in a row pointed toward the mirror. I am thinking of making a part to fit in it's place to hold the lense on the top side and the LCD on the bottom side. Using the existing setup the angles should all be ok if I can get the focal points to workout. Can't decide whether to put a PC with a capture card and descaler software or to use a XGA Theater line doubler. Also thinking about using one of the 7" lcd's that ace used in his projector. That is a nice setup. With the RPTV being all enclosed I am not sure what to use for a light source. Should not need as much as a regular projector due to no ambient light. So I am thinking that a 150 watt should be more than enough. Maybe even less. I am going to see about renting a LCD panel for a OHP and do a little testing with light sources before I spend any money. Hang it in the box behing the screen and put the light behing it and hang the back on and look at the screen for an idea of how bright it is. Any thoughts on this anyone. I would like to get a picture like a HDTV has if possible. Bigger is nice but quality is the biggest thing I am after.
David
dbc105

Nevermore · 21st January 2004, 11:34 PM

Quote:

Originally posted by karmaz

Hi Nevermore,
I'm very interrested by your experience!
Can you give reference (12128001 ?), price, specs, resseler of your screen ?
Results of different sample ?
Any snaphot of the screen ?
Details of your box, type of mirror...

Thanx
The French guy...with the very bad English

I'm a little behind schedule, but I will try to post some pictures and details soon.

dbc105 · 22nd January 2004, 12:13 PM

that would be a big help Nevermore.
Thanks

dbc105 · 27th January 2004, 05:55 PM

Ace, you had shown some interest in RPTV. what thoughts and ideas do you have on it? how would you set one up? would you use the 7" lilliput and the mirror setup?

Nevermore, are you still here?

David

ace3000_1 · 27th January 2004, 06:04 PM

heya buddy sure just time is taking my interst in this feild away right now but its doable with a lilliput lcd, i probally would use a mirror, before the mirror there would be the lcd at the bottom with its light engine, then after the lcd i would magnify the image to a mirror so the image is bigger and u have a larger more even throw area, then it should project onto the screen from a right angle, u would need a short focal lens for this and a very bright light, if u wanted to get the best results maybe use a frensel behind the screen the same size as the screen but i gather this may give u a viewing angle problem, but without the frensel behind the screen the image would be very even if you set the optics up right in the light engine.

Trev

rmccoll · 27th January 2004, 06:25 PM

I know the 7 inch lilliput is a good lcd, but does any know about the 1.8in lilliput lcd? I just ordered off ebay.

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13th January 2004, 12:15 PM	#41
dbc105 diyAudio Member Join Date: Jan 2004 Location: Alabama	well I picked up 3 bad RP big screens this weekend. I have not had a chance to pull the backs and take a look but plan to do that this weekend and see what I have. I can see in the lower front of one and it has 3 CRTs pointed toward the rear at an upward angle so I am guessing that they are pointing at a mirror. it maybe that I can position the projector part where the center CRT is. rmccoll, do you have any more pics of what you built? Landers(the tv repair guy) said he had several of these things in his way so maybe I can get lenses, fresnels, etc... David dbc105

13th January 2004, 02:25 PM	#42
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	yea, thats what you should do. remove teh CRTs, and have the projector lense where the green CRT was. If it were me, i would attempt to repair the RPTVs before I use them as projects. I just got a 53" i found of the street, and im currently ordering a vertical deflection IC, which is $4!! thats all thats wrong with it, along with a fusable resistor. and a shorted DC supply diode. after this, alls well. ALSO, if one of your 3 sets has a magnovox PTV-375 chassis, I need the convergence waveform board(the one with 40 knobs). shout at me if you find one.

14th January 2004, 11:49 AM	#44
dbc105 diyAudio Member Join Date: Jan 2004 Location: Alabama	mbates14, not much chance in repairing any of them, the guy I got them from repairs TVs and a lot of parts have been robbed from each one of them. But, they do have screens, lenses, mirrors, etc... That should save me a lot of time and money in the start. Question, will using a LCD monitor screen instead of a panel get the picture quality up to High Definition? I stumbled upon a projector site the other day and the guy was using a LCD monitor and a line doubler on his projector to acheive a very high quality picture. Also, how would you go about getting wide screen? David dbc105

19th January 2004, 06:17 PM	#45
dbc105 diyAudio Member Join Date: Jan 2004 Location: Alabama	Well I got the backs off the 3 RPTV I got. 2 of them use a single mirror to reflect the image onto the back of the screen, the third tv uses 2 mirrors, a small one down low and a large one behind the screen. One of these is a Pioneer, it looks to be the best choice. The CRT projection lenses are bolted to a metal plate in a row pointed toward the mirror. I am thinking of making a part to fit in it's place to hold the lense on the top side and the LCD on the bottom side. Using the existing setup the angles should all be ok if I can get the focal points to workout. Can't decide whether to put a PC with a capture card and descaler software or to use a XGA Theater line doubler. Also thinking about using one of the 7" lcd's that ace used in his projector. That is a nice setup. With the RPTV being all enclosed I am not sure what to use for a light source. Should not need as much as a regular projector due to no ambient light. So I am thinking that a 150 watt should be more than enough. Maybe even less. I am going to see about renting a LCD panel for a OHP and do a little testing with light sources before I spend any money. Hang it in the box behing the screen and put the light behing it and hang the back on and look at the screen for an idea of how bright it is. Any thoughts on this anyone. I would like to get a picture like a HDTV has if possible. Bigger is nice but quality is the biggest thing I am after. David dbc105

22nd January 2004, 12:13 PM	#47
dbc105 diyAudio Member Join Date: Jan 2004 Location: Alabama	that would be a big help Nevermore. Thanks

27th January 2004, 05:55 PM	#48
dbc105 diyAudio Member Join Date: Jan 2004 Location: Alabama	Ace, you had shown some interest in RPTV. what thoughts and ideas do you have on it? how would you set one up? would you use the 7" lilliput and the mirror setup? Nevermore, are you still here? David

27th January 2004, 06:04 PM	#49
ace3000_1 diyAudio Member Join Date: Mar 2003 Location: spain	heya buddy sure just time is taking my interst in this feild away right now but its doable with a lilliput lcd, i probally would use a mirror, before the mirror there would be the lcd at the bottom with its light engine, then after the lcd i would magnify the image to a mirror so the image is bigger and u have a larger more even throw area, then it should project onto the screen from a right angle, u would need a short focal lens for this and a very bright light, if u wanted to get the best results maybe use a frensel behind the screen the same size as the screen but i gather this may give u a viewing angle problem, but without the frensel behind the screen the image would be very even if you set the optics up right in the light engine. Trev

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