LED Projector Lamp V.1.0




Introduction: LED Projector Lamp V.1.0

About: I am a graphic designer with many hobbies. I love electronics, computers, LEDs and all things tech.

My first video projector. Ever.

Last year I came across a cheap Toshiba TLP T70M projector on some e-bay wanna-be site over here in Romania. It had no lamp at all but other than that it was operating properly (or so the salesman told me). I traded it for a Shuttle computer I had in my closet and in a few days the projector was delivered. I was surprised that it was in a good condition, I was expecting cracks and scratches, it had none. I turned it on and - predictably - the “lamp missing” LED came on in about two minutes. At this point the projector shuts down automatically. During those two minutes I was able to see the startup screen by looking thru the lenses while holding a small flashlight where the bulb was supposed to be. So yes, it was operating.

I started google-ing all I could find about this projector. I came across the complete Toshiba TLP T70M  user manual (it had none when I received it) and that’s about all. At this point I wasn’t really decided what to do, I was tempted to buy a light bulb for this model and use it as anyone should. On the other hand being horrified by the huge price that projector bulb had it was clear I had to find an alternative light source. Me being a LED addict I started thinking about that. It was the obvious choice but the problem will be the light output. The projector’s lamp had 2000 lumens and in “eco-mode” had 1000 lumens. I was aiming for his lower figure as I won’t be using the projector in daylight anyway. So my goal is 1000 lumens of LED light.

Insert a few weeks of random ideas and pointless calculations here. Lazyness, to be more precise.

Step 1: Parts Used

I decided I will buy the most powerful LED I can get my hands on and try to use it as a light source in my projector. All this without being distructive or making irreversible changes to the projector. Google that and it turned out my only choice in power LEDs (over here, in Romania) was a Cree MC-E M, Star, White, 752 lumens output, 4 chips, 110 degree (light beam). I was hoping for a OSRAM OSTAR rated 1000 lumens but the reseller couldn’t provided it.

The original projector lamp had 2000 lumens and 1000 lumens in eco mode. I figured if I get close to that eco-mode it might be usable in my tiny apartment. This LED is rated for 50.000 hours of operation and is considered equivalent with a 75W incandescent bulb. I also ordered a 700mA constant current power supply to power it. This one is rated up to 30V DC output @ 700mA and is powered by grid power (220V AC here). I plan to hide it inside the projector once the project is successful. But enough daydreaming.

Step 2: Electronics Involved

The first step was to fool the electronics into thinking the lamp is present so that the projector will start operating properly and get rid of that automatic shutdown. A few Google days later I came across a French site on the very same subject. It turned out all I had to do was to find a logic signal that was up (5V) during the first two minutes and down (GND) just before the LED missing indicator turned on. I found it eventually, using my multimeter. By pulling this signal up (a simple wire jumper connected to a 5V source I found on the board) it started normally thinking the lamp was present and on. I connected a laptop to it and checked that the movie was playing by looking into the lens while holding the same flashlight inside the projector. Yes! I was glad I did this, I’m not that experienced in electronics and I feared I may end up stuck at this stage.

Step 3: Construction

I ordered the LED and used a heat sink I had around from an old Pentium I. As space is an issue, I had to make sure the LED bulb will fit. This heat sink was the only choice. The LED came mounted on a small star heat sink so I drilled two holes for the screws in the Pentium heat sink to attach it firmly in place. Arctic Silver 5 thermal compound was used in between those parts. After wiring the LED (the four chips had to be connected in series first) I scavenged a flashlight for the light reflector. Inside that I put a 45 degrees matte lens I also ordered in order to make the light more focused and uniform as the four chips are not a single light source but four, close to each other. I also used two PCB boards I cut to make the bottom and the top of the light bulb. This was needed to make sure the bulb wouldn’t move inside so I cut them to the exact shape of the existing space.

Step 4: Testing the Bulb

The bulb was powered using a 700mA constant current power supply. As each chip needs 3.5V@700mA the measured output was 14V@700mA. That’s 9.8 Watts... my mind instantly told me it’s not going to be enough. But we’ll see. Anyway, it’s well below the max 30V this power supply puts out. I was a little worried about the amount of heat but as it turned out the heat sink barely gets warm, thanks to the built-in fan this projector already had for cooling the bulb.

In this picture you can see the bulb, the flash light made its light beam look weak but trust me, it’s strong and blinding if looking directly to it. It’s not recommended either, actually.

I mounted the bulb inside and proved to fit perfectly. I used the original bulb mounting holes. First tests, as you can see were indeed, disappointing. This projector being a LCD-type (unlike the better DLP ones) proved to eat up about half of the LED light output when displaying anything. This I wasn’t expected. Lack of experience and knowledge, I guess. I was quite disappointed finding this.

Step 5: Conclusion

In a completely dark room I was able to watch “Avatar” but the dark scenes were too dark. As you can see, the scenes that were full of light were almost viewable but that’s about it. It’s clear that I need AT LEAST a double amount of light. 750 lumens is nowhere near enough. Besides, not having a luxmeter I suspect that only half of that reaches the screen. It was fun nevertheless to play with a projector for the first time. I like it and I’m determined to use it. Time to get back to the drawing board. I need more power, more light, all within the same confined space.

Step 6: To Be Continued

Months passed and I still look for a better LED. I decided to try a second version of this light bulb. This one will use an array of 9 x NS6W183T Nichia LEDs. Rated at least 225 lumens each, I should have in excess of 2000 lumens of light. If 1000 lumens of those do reach my projection screen I will be happy, that’s the “eco mode” I was hoping for. The main issue with this attempt is that I have to keep the light source as small as possible while focusing it on that Fresnel lens inside the projector that’s 3x3 cm small. Oh, and the entire LED bulb has to fit a 5x5x9 cm space. Small space for serious power and an estimated 35 watts of dissipated heat. But I won’t give up. Look out for my next instructable on V2.0 once the 9 LEDs array is ready. Right now we’re about to have a baby so it’s standby for everything else. J

Thank you for reading this. Feel free to ask any questions, I’ll try to answer them.

Edit: our baby was born today! I'm the proud daddy of a very cute little boy!



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    138 Discussions

    Nice post friend.I bought a panasonic pt ax100u projector which has a bulb expected to live around 800 hours around 700 it started to shut off once then have to be turned on and worked fine...well after 4 months later and having to turn the darn thing on 5 times before it stays on im curious as to if its a bulb issue or something else.

    for more details: http://www.tvlampsforless.com/

    4 replies

    Thanks. You do have a bulb issue. The gap between the bulb's electrodes got larger (that's the actual wearing of the bulb, the electrodes slowly consume themselves) and the power supply circuit cannot sustain the power needed to generate the electric arc. The protection kicks in and you have a lamp in need of replacement. The on and off thing works for a short time, but the end of that lamp has come. Replace it or convert your projector to a HID lamp. You'll need a shunt on the mainboard to fool the projector the lamp is fine, a HID ballast, an external PC power supply, a modified bulb .... it's doable but definitely NOT for the average user. Oh, and it's a major violation of warranty terms :-)

    do you have a recommended source for details on HID conversion, when I google car headlight results are returned :( Can the HID be powered for the existing power source?

    And no, you need to also use the new HID power supply. On a proper conversion, the original lamp's power supply can be removed, leaving room for the new one.

    hi i have my projector with 2000 lumens can i increase lamp capacity to get 4000 lumens. Mine is 220v 230w lamp as of now.

    Might you do a photo of the bridge of wire? It is that I have not still had it very clear, I have the same projector. Sorry my english


    2 years ago

    hi, LED light is a super idea. how about testing the projector with a cheap strong LED torch like this one on eBay: 3000 Lumen Zoomable CREE XM-L Q5 LED Flashlight Torch Zoom.

    Good luck...


    3000lumen torch eBay.jpg
    2 replies

    Hi there,

    No, I haven't. I wish I would. However, I doubt it will last. I tend not to trust Chinese overpowered LED items. I just don't see it lasting hundreds of hours on external power supply.

    Never trust chinese figures on Lumins or battery specs..they all come far below listing..Ebay is becoming a platform for Chinese fraudsters. After years i am trying to break free from Ebay and paypal..both team with scammers.

    Great post and funny comments..especially when u mention the day dreams n laziness virus which all DIY people have..great post thumbs up.

    I have done this before ran into an issue though the light I got was massively bright and hot melted the case and the color wheel never really messed with the type of light I purchased before but hoooo man you want to talk about blinding light this thing was insane.

    On a side note a typical 100wat bulb is 1600 lumens ... But I think the fella that had the idea from the car light hit it right on the money... Anyhow your post is fairly old and LED has come a long way since then so I am sure you have found the way... Easy way to find the circuit to trick is look for two optocouplers actually often you can just trace these out and just cut and splice wire that is there to make it work.

    Anyhow I enjoyed your posting a bit nostalgic for me ;)

    Just use a 4300 k cheap ebay 35 w Xenon bulb powered by a cheap ebay ballast (14V input) that are made for car xenon retrofits. It will cost you about 30€ and the best part is it doesn't need any heatsink.
    LEDs have a long way to beat that still.

    1 reply

    ... There is also a choice of getting a 55w ballast. The xenon bulb stays the same. Light output is about 30% greater than it is with 35w ballast.

    Hello all! I have the CL312A LED Projector that I bought from Ebay. After a year of usage, suddenly one day it stop producing image but only sound. I guess I need a lamp/bulb replacement. Though, there is nowhere inside the manual any instructions on where is the lamp or how I can replace it. Could anyone please help me with some instructions pleaseeee????????????

    I have your lumen solution.


    I would go with the 50 watt bulb. You will definately want a bigger heat sink too

    I think you're making a mistake with your lumen comparison here. The advertised lumen output for a commercial projector is referring to the final light output from the unit, not the raw lumen output of the bulb, so if you put a 752lm LED into the projector, you'll likely get between 10-30% of that after the light has passed through all the apparatus, much lower than your target of 1000lm.

    1 reply

    You are right. I learned this the hard way. That's why I stopped developing any projector LED light bulb. DLP projectors are better as those won't take that much of the light output. But with LCD ones, it's a painful experience.