EPSON 755c LED MOD - diyAudio
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Old 10th September 2009, 03:55 AM   #1
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Default EPSON 755c LED MOD

Well I am working on modding a little Epson 755c. This projector is nice and small and the light inlet for the lamp is about 1inch square. From testing it is giving promissing results.

I have a question for the projector guru's. Projectors require a point source for the light. What happens if theres mutiple points like 2-3 that are focused into the tunnel? Would the fly-eyes lens spread the light evenly? and would the brightness improve?

I was looking into this optic with the rebel led
http://www.luxeonstar.com/polymer-op...leds-p-424.php

The beam is highly concentrated at about 14mm with an angle of maybe 3degrees.

Last edited by crazifunguy; 10th September 2009 at 04:19 AM.
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Old 17th December 2009, 05:44 AM   #2
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looks promising, havent run any numbers however i highly doubt this would compare to brightness you currently get, why dont you go for the MH replacement lamp most people are going for instead? it seems you want to put a bunch of different leds and concentrate them in a honeycomb sort of way but what you really need is the highest point of light concentrated on the smallest area possible, so maybe a bunch of leds with the right concentrator lens, sort of what you see on projector headlights
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Old 17th January 2010, 10:33 AM   #3
Bohanna is offline Bohanna  United States
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Hi Folks,

Here is a C/P of something that I posted Dec 16 2009 on another board.
This thread seems more like the place it might do some good and hopefully tickle some minds.

Hope it leads to something.

Bohanna

The C/P >>Just curious ?? Has anybody tried or had any luck using three high powered LED arrays instead of a single one retrofit into a commercial projector? I have seen several attempts with a single LED panel but just like the larger arc chamber metal halide lamps they don’t produce enough focusable light to be useable. Instead of using one LED panel that is being fed through a single lens and mirrors in order to supply the light to the three LCD panels I am curious if it may be more productive to triple the LED power? I am thinking about mounting three individual LED panels directly behind the LCD’s just before the light enters the micro lens array prisms block. I am assuming this will increase the useable light significantly and allow for the individual tweaking of each LED panel to achieve better balance and color convergence. Also since most of the LCD prism array blocks already have fans in place for cooling I believe the same fans would keep the LED’s Cool. The essence of what I am talking about is going back to the original 3 CRT tube principle of having three individual color and sources combined and converged instead of using one source performing triple duty. I just don’t’ know if I want to spend the 300+ dollars on LED panels now that the price of sealed beam UHP lamps has come down.

Many Thanks in Advance,

Bohanna <<<<
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Old 18th January 2010, 02:17 AM   #4
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Quote:
Originally Posted by crazifunguy View Post
Would the fly-eyes lens spread the light evenly? and would the brightness improve?
Fly-eyes before the tunnel or after?
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Old 18th January 2010, 04:03 AM   #5
Bohanna is offline Bohanna  United States
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Quote:
Originally Posted by crazifunguy View Post
Well I am working on modding a little Epson 755c. This projector is nice and small and the light inlet for the lamp is about 1inch square. From testing it is giving promissing results.

I have a question for the projector guru's. Projectors require a point source for the light. What happens if theres mutiple points like 2-3 that are focused into the tunnel? Would the fly-eyes lens spread the light evenly? and would the brightness improve?

I was looking into this optic with the rebel led
Polymer Optics Concentrator Lens with Holder - Fits Rebel LEDs [141-180]

The beam is highly concentrated at about 14mm with an angle of maybe 3degrees.
As long as you can spot beam the light sources in into the Fresnel (fly eyes)
I think it will work. I believe this is what makes the short arc metal halides (UHP's)so effective. They form a very tight beam with a hot spot in the center. The LED brightness is not as important as how narrow the beam is.
I have spent a LOT of time and MONEY finding this out first hand. The long arc metal halide lamps will not work well in commercial projectors because the LCD screens are so small. You can get them to fire up and put them in reflectors but they will still be too dim. Think about my three LED idea. If it works you woundn't need the light chamber the fresnel and the mirrors

Bohanna
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Old 18th January 2010, 10:59 PM   #6
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The 3 LED will require a separate control board and a software programmed as per Elektor. It would also be very difficult to align the LED's for optimal performance. But I agree, that light tunnel, color wheel and the mirror does lose a lot of brightness.
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Old 19th January 2010, 12:14 AM   #7
Bohanna is offline Bohanna  United States
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Quote:
Originally Posted by Gizmotech View Post
The 3 LED will require a separate control board and a software programmed as per Elektor. It would also be very difficult to align the LED's for optimal performance. But I agree, that light tunnel, color wheel and the mirror does lose a lot of brightness.
Nope I think not. Mount one LED panel behind each of the three (RGB) panels/They are ALREADY lined up. All you need is a light source. It has nothing to do with controllers. All the mirrors do is channel the light beam within the projectors light chamber after it has left the lamp and gone through the fresnel/Fly eye lens. People have already tried to retrofit a single source LED but it is always to dim to compeat with a UHP's beam. I am suggesting trippling the light power and placing it much closer to the output lens.

I have attached a diagram of what I am talking about. You can mount the LED's at point 6, 6 and 7. So they shine into the LCD's at point 12,, 13,, and 14 . The rest of the light engine would not be needed as it is what is used to bend the light around the inside of the projector. also the 3LCD have a fan already mounted below them that could be used to cool any heat the LED's produce. You can also channel any exhast heat the LED make through the now empty light chambers with a small boxer fan

Bohanna
Attached Images
File Type: jpg Bohanna's 3 LCD block and Light chamber.JPG (114.8 KB, 251 views)
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Old 19th January 2010, 12:30 AM   #8
Bohanna is offline Bohanna  United States
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Default another prism shot

Here is a another drawing and view of the actuall LCD prism array. It is from a different projector but it is pretty much the same.

Bohanna
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File Type: jpg Bohanna's 3LCD prism Block.JPG (36.7 KB, 241 views)
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Old 19th January 2010, 09:53 AM   #9
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Currently I have the light tunnel removed completly and will try led's with lenses going right into the 3 LCD panels. Pics soon...
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Old 19th January 2010, 12:45 PM   #10
Bohanna is offline Bohanna  United States
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Quote:
Originally Posted by crazifunguy View Post
Currently I have the light tunnel removed completly and will try led's with lenses going right into the 3 LCD panels. Pics soon...
Cool!! If you want to get a better set of picts of the projector I uploaded Try Googleing PLC-SU20B.PDF service manual and see if you can find it. Make sure you get the SERVICE manual and not the user manual. It has a very detailed set of drawings Here is the link to where I got it.

Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics

Good Luck

Bohanna
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