Inside the projector is a lamp inverter board that produces the voltage and pulses to operate the lamp. You cannot power that led driver from the projector lamp output. And you can possibly destroy your multimeter due to the pulses.
The Projector lamps use a regulated power supply meaning it will drive the voltage to meet the current it is supposed to operate at, or at least that is my understanding.
when i discovered your channel nearly a decade ago, you were restoring an old honda 3 wheeler. that series got me hooked. did it ever get finished and what became of it?
The original bulb is probably some manner of arc lamp. It takes a high voltage to ionize the gas in the bulb, like in the KV range, and once struck the voltage drops and the power supply reverts to constant current to maintain intensity. Hard to beat the the efficiency of the original lamp with its built in reflector designed to concentrate all of the visible light from the arc lamp towards the screen, while allowing the heat, etc. to escape. The Original bulb looks cool because it is.
Best to replace the original bulb because an led without a reflector would already be like 5x more efficient, and plus these bulbs are getting expensive
I have the same make old projector still have a new spare bulb , as you said the type of lamp needs a high strike voltage to get the bulb started , not sure what the voltage and amp draw is once the bulb is up to operating temperature , not a good idea to use the built in power on an LED 🙂
@@uptowndisco2 I guess it is possible to remove the internal metal halide lamp inverter from the projector, replace it with an led power supply, figure out and circumvent the lamp failure control circuit, modify the lamp housing to hold an led with heat sink. Led should match color temperature as closely to original lamp or color won't be correct and all should be close to good. Maybe.
The regular lamp must be started with higher voltage. Startup voltage is high but after the lamp starts the voltage drops under 100v. The projector tryes to start the lamp multiple times, and after several failed attempts it shuts down. To make it work u must moddify the lamp driver board, and make the main poard thinkl that the lamp is started and working. Kinda pain in the but to make it work.
Is the bulb it uses normally a sodium arc lamp (HID bulb)? If so it will use a HID ballast, these are pretty scary in terms of operating, (high voltage/frequency) can sustain a small arc in air. IIRC they use a high voltage/frequency to ignite the arc and melt the sodium, once molten it drops to a lower voltage/frequency. So you're probably right in thinking bypass the inverter/ballast (assuming it uses a HID/molten sodium bulb).
So the lamp is AC, it uses a huge inverter and a ballast to start and run the lamp. The best thing to do is to remove the ballast and run it from the power supply, use a relay to turn it on and off with the projector.
Can you put videos about the vidoe and picture quality of this 3M projector? Its contrast ration is 400:1. So, what does it looks like when it project image, videos and films?
It's probably for the best since we could make little kits to upgrade them to LED fairly easily. I had almost forgotten about this project, thank you for reminding me.
a lot of buck converters need some sort of load, as the pulse width often cant go down to zero. So without any load the output voltage might be the same as the input voltage. Also the original lamp is probably a point source of light, while the led has a large area that produces light. so not all that light might be used. Maybe if you move it forward a bit .. so it fits the cone of light the lamp produces.. There are these LED lamps for cars that are small but still 160 watts or so, they might be a better point source of light.
ya thay run on high kv. you better off running a external psu. i have one here from a thrift store and looking to do the same. also that led needs a good heatsink to stay cool. >:)
I think you're onto something with cutting the AC power supply out of the equation. I mean, you just need 2 DC rails. One that has the right power for the mother board, and another that has the right power for the LED. :) (Yes, I know I'm stating the obvious. hehehe)
BTW: this lamps have a view 10s of kV high frequency high voltage. you probably damaged your DMM input protection MOV by sticking it in there. this Projektors use "Ultra-high-performance_lamps" (actually a technical therm) and they are orders of magnitude better then LEDs for hist application because they have higher intensity. Ti has good video on this topic: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3ItoGhwWsG0.html LED Projektors need highly specialized LEDs for this application or Laser.
You need more experiment with metal halide or UHP bulb ballast circuit. Find ballast to mainbord connected wires to wich one is error reporting. Make that signal from external circuit to fool motherboard. This is not a simple DIY game. Try harder.
