Wednesday, March 27, 2013

Epson emp-s4 Projector LED Mod

Recently during one of my Ebay window shopping sessions I came across a listing for an 'as is' Epson projector missing a lamp. It was sold as is because it would turn on and then simply flash a lamp error and since the lamp is much more expensive than the projector as a whole, the seller undoubtedly decided to sell just the projector rather than purchase a new bulb. The best part was that he was willing to part with it for $25 with free shipping. As far as I could tell nothing else was wrong with the projector so I took the plunge.

While waiting for it to ship I read up on the control systems that these projectors use in order to control the ballast and lamp assembly. It looked like nothing more complicated than tricking an input to the main board to make the projector think a real lamp was inserted while in reality I would use a high power LED but more on that later. 

A week later it arrived in a huge box and as I hurried back to my dorm room I tore it open in excitement. It has three lcds, one for red, blue, and green. These three images are added together with the help of a lens to create the final image. The next step was to remove the ballast and figure out how which two wires from its control cable sent the lamp ok indication. I noticed that the ballast (the circuit board on the bottom left in the picture below), had a digital control circuit mounted vertically with three optoisolators near the i/o cable. These chips are necessary to insure that the digital low voltage i/o dont mix with the high voltages present in the rest of the ballast or else this projector might release its magic smoke. In addition two of the optos were facing left while only one was facing right. This hinted to me that the one lone opto was the output sent to the main board pictured in the upper right below to tell it that the lamp was operating perfectly fine so that the projector would stay on instead of shutting off and giving an error like it would without a lamp inserted.

So my solution was to short out the two wires that led to this opto (found with the help of my multimeter). I also needed to tape down the lamp door safety open switch so it could operate with the cover off. Now when I shone a flashlight into the lens input on the upper left of the image above I could faintly see an image being projected from the projection lens on the bottom right. Bingo, now I was getting somewhere. Now I needed more POWER!

I had bought a 30W 2000 lumen LED and 2A ac/dc driver in anticipation of this exact purpose a while ago so I dug that out of my parts bin along with some optical lenses to focus the light. I drilled into an old pentium cpu heatsink and attached it to the LED because after a few seconds it got rather hot. The fan came with the heatsink so I just wired it up in parallel with the exhaust fan seen below to the upper right of the picture. Then I used some framing wire to attached the glass lens to the assembly. This ensures that the light is concentrated and evenly dispersed into the small window to the left.

 Next I need a way to turn on and off the led because having the light on all the time when the projector was plugged in was no fun. I could have gotten fancy and dug into the buck control circuitry of my LED driver and done it that way but I opted for a more universal approach in case I wanted to upgrade the light source in the future. I patched a ac cable into the power input of the projector's main power supply board to gain access to 120V AC. Then I used a beefy relay pulled from an old computer battery backed ups (uninterpretable power supply). This small beast could handle 5A at 125V so it should be sufficient for the task. I placed out of the way it in a crevice in the bottom left of the projector as seen in the picture below. Normally when the coil is unenergized it opens the circuit so the LED is off. When it receives the signal from one of the other optos (I carefully tested with the projector open to see which control line to the ballast changed when the projector was turned on and off) it sends current through the relay switching the AC voltage into the LED driver thus turning the LED on. This way the hacked on LED would behave exactly like the original lamp: it turns on and off with the projector with no user intervention.

The LED driver in the protective plastic shield on top of the main power supply can be seen above in addition to the small optoisolator and flyback diode circuit I built to handle automatic relay control to allow the projector to turn on and off the LED itself.

I pulled ground and +12V for the relay coil from these two spots on the main board.

Finally a picture of the entire device fully modded to my liking. Its a thing of beauty.

Now for a test I played some video games on it for an hour and measured the internal temperatures to make sure that it would be fine. Here is a projected screen size of about 30" in pitch black room for your enjoyment.

And what game did I test I hear you ask. Only one of my favorites of all time ;-)

These images were about 30-35" diagonal. Not too bad. They look better in person its just that I had to use my phone cameras as I forgot to bring home my nice Sony camera for spring break. I can push the image to 45-50" and still be viewable in a pitch dark room but brightness degrades quickly. I'll see if I can get my hands on a 8000 lumen 100W LED and make this almost as bright as it originally would be with the stock lamp. Here is a quick video of the internals and it operating for those who are interested.

For now I will go ahead and call this hack a success. Now let me get back to beating Castlevania Symphony of the Night for the millionth time ...

If you have any questions feel free to comment below and I will do what I can to help.


  1. Nice hack.
    Make sure you post an update if you upgrade the LED.

  2. Can you post a link to the LED you bought?

    1. Here you go!


      LED Driver:

  3. I did this to a Panasonic projector, and i'm in the process of doing this to an Infocus projector. Good fun. gotta be awful careful of the high voltage when probing for lamp ok signal.

    1. When doing anything high voltage always keep one hand in your pocket and use insulated tools!

  4. Could you post a pic of the lens you used? I think that's the only piece missing here, for me. Thanks!

  5. Very good friend! surpriendente! I really liked your project! most did not quite understand how the binding of that plaque, I have the same projector epson s4, you could send it to my e-mail more detailed scheme for me to do one like yours? would appreciate it! Thank you!
    My email:

  6. Hmm, good project I think, but it is useable only for small diagonal image than you mentioned above. In this case the price of all components + lamp life (price/power), is better solution than classic (stock) lamp.
    100W Led for higher image + flyback converter it may not be as good a solution as stock lamp.
    Well done! =)

  7. Very cool. Im now super curious about the 100w led though as I have a dead home theater projector lying around.

  8. I would think modding an already factory led projector, like the Favi Rio for instance, with a more powerful led, would be a little easier?

  9. Hi, I have an Epson EMP X3 that uses the same motherboard. Can you tell me which cables (brown, red, orange, yellow and blue) from connector I need to short to fool the lamp sensor?

    1. I'm up at college right now and left this project at home so I unfortunately cant open it up to take a quick peek to tell you which wires to short. If you still have the original ballast you can trace each control line to a few four pin devices which are optoisolators. My ballast had three such devices and they were lined up but one was facing the opposite direction of the others. This hinted that two were for data out and the last was for an enable input. Find the one optoisolator that is facing the opposite direction of the others and trace its wiring to the cable harness. This should help you figure it out. If not I can check when I go home over thanksgiving break.

    2. Hi, thanks for the info. I've figured out, but I need to find a good light source. What kind of lenses did you use and where can I buy one? Did you remove any lenses from original projector?
      Thanks again!

    3. Hello Miky Smart, if you are kind, write here what colors are those wires you have find to shortcut?
      I have same product at home and just find out this post I want to try.
      Thanks in advanced

    4. Hi Mihai Achim, sorry for my late reply but I wasn't home this past weeks.
      I have shorted the red and brown wire that go from motherboard to the ballast. I have removed the ballast.
      Hope it helps you. Post your findings regarding the light source. I still need to build mine (lenses, LED and LED driver).


  10. sjm4306 - thanks for you idea, is really great,
    You are very inventive, :)
    If you have time when reach at home may be take a look at that wires ? Sure if meantime Miky is arround.
    I am just an electrician :( so with LED I can handle but opto... :(

  11. I posted this on another thread and I'll try here to see if I get any responses too. I’m doing a mod with a 100w led in an Epson power lite 8350. I’ve got the bulb assembly finished and it stays at 90 degrees Fahrenheit. The issue I am having is making it sense the bulb is working. I tried shorting the brown and red wires because they were on the flipped opto. This did not work. I put it back and have since been messing with the yellow wire. When a good bulb is installed it reads 1.2v. When no bulb it reads 2.6v. I dropped the voltage to make it 1.2 but the projector thinks it is overheating and the bulb is blown. If anyone has any ideas let me know.

    1. Hello, I'm just like you but with a Epson EB-S02
      you have made ​​progress? There is very little about the topic on the network, I tried different search engines and more than a thousand combinations and I can not find anything of value.
      There must be something more in these newer projectors.
      and I thought this was too easy lol
      good luck!
      and if I give something I commented.

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  13. how did you test/find the +12v and ground for your relay coil on the board.

    1. Ground was just pulled from the ground plane on the main pcb. For the 12V I just pulled it off of the output of the powersupply right next to the connector. I used a multimeter to probe the voltage of each wire coming from the power supply until I found the right voltage.

  14. I think most of individuals posting comments here speech that paramount projectors area unit junk unit those who haven't used a dominant projector or haven't seen it operative. I preponderating smart-905 from space|a neighborhood} bourgeois in my space and I’m really happy with it. I watch blue ray movies with it and so the images unit unceasingly sharp. I even have set the screen to 90” and so the images seem to fill my space. I even have seen someone speech that variety of the buttons don’t work. Well, that is contrary to my experience; all the buttons unit operative totally. i want to mention that I’m really happy with my purchase.

  15. (Epson EMP X-3) Thank you. Brown and red wires correctly. Both did not short-circuit. Lamp control card had been disabled.

  16. Hello,
    Epson emp-s4 Projector LED Mod is a nice blog.So many informative ideas and information s are there.I like this blog.Thanks for posting such a nice blog.
    LED Projector

  17. Thanks for the hack. But can you exactly say which pin of the odd opto isolator to which pin of the normal opto-isolator. There are 4 pins to each opto-isolator. I am bit afraid of shorting the wrong one. I am not an electrical engineer. Please help! Thanks

  18. To Selwyn ross.You need to find part number of actual optocoupler and then download or find online info about pinout.
    Most common 4pin optocouplers have dot mark 1st pin on one corner which is anode so 2nd is catode then you need short 3rd and 4th which are transistor to make it,but check it first,dont wanna blow it.
    I am working currently on Led mod for Infocus LCD where I used 100W-6000K-9000LM led but result is still too dim to be watch-able.
    LCD light engine need to be filled by huge amount of ANSI lumen’s source to produce enough light for good image result as there is too much brightness loss when light going though color filters and other parts to optical lens.
    There is no problem to cool down 100 watt LED but higher wattage would be power hungry and need more cooling.
    There also any light escape from light engine will affect final relult in brightness so be careful with the gap between bulb and input square hole where light is incoming to convergence lens.
    Have a nice DIYing
    Regards Ronan

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  20. Has anyone modded an epson power lite home cinema 8350? I really don't want to buy another 250 dollar bulb.

  21. Dear Friend.
    I have a EPSON EMP-S4 projector with the original source damaged. I bought and I received the led lamp and the driver you recommended on your blog. I've also got the heat sink with the cooler from an old PC.

    I really need your help to make the card with the opto coupler that connects the power supply to the relay. You can provide a wiring diagram with the proper connections or more detailed photos of the project?

    Thank you for your attention and sorry the job.