DIY replacement lamp for projector

[mathias]

Good to hear that more people than I are trying this, also nice to hear that they use opto-couplings, that makes this thing more easy, I wondered how they know when the lamp has warmed up, but now I know that they can use opto-couplings. In my case I have a 20pin connection from the PSU so the problem is which pin do I have to pull down to 0V. The biggest problem I have is that I can´t get into the PSU without to take everything out of the projector.

As I have sad before I think this is the new DIY-video thing most people want to do in the future. Pro-projectors have all the advanced optics and electronics and better lcd:s already built in that diy-projectors can´t compete with. A pro-projector without the UHP-lamp is only worth the half of it´s price and that makes it more cheap than any other diy-projector. And the best thing with pro-projectors is that you can sell it, if you don´t want it. DIY-projectors is quite hard to sell ?

[Tuga]

Hi,

I had a lot of big connectors from my main board to the PSU.
But these wires were going to what was easily identifiable as the low DC regulation part of my PSU (not live).
The connector that did it for me was actually on its own, 3 little wires…lol.

If it helps look for a chip with the numbers ***494** (ex:TL494, M5T494P or equivalent)
This is a PWM chip that controls the output of the PSU. Basically I THINK this chip controls the voltage after the ignition pulse.
Somewhere around this chip you maybe able to find the 2 Optocouplers u are looking for.
I don’t think it knows if the lamp is warm or not, it only knows if the arc has been formed.

My optos were made by Sharp, PC123 chips.
As I said, the igniter and optos are no longer inside my projector so I’ll take a picture when possible.

At the moment I am looking at trying a 240v 300w linear Halogen lamp (78mm) on mine, since I can’t find an easy ( and small ) way of powering a 24v 250W halogen one.
The lamp compartment should be just big enough since it has an 80mm fan at the end.

Has anyone actually tried to use a normal compact metal halide lamp on a Pro projector with the projector’s ballast and igniter??



If any one has any ideas …...

[Tuga]

Hi,

Here it is as promised, a pic of the half of my projector’s PSU that is no longer used.
Inside the red circle are the 2 OptoIsolators and 1 end of the cable that connects to the main board,
Inside the yellow one is the 494 PWM chip that is supposed to control the output.
Inside the green circle is the other end of the cable and the drawing of the 3 lines ; “PowerOn”, Ground and the so important +5V that has to be pulled low.
The 2 squares on the schematics represent the “insides” of standard OPTO’s.


Hope this helps.

[slickwillie]

OK, here's a pic of the PCB (sorry for the crappy quality, my camera has no macro mode, so I had to use the old magnifying glass trick). I circled the 2 chips and cable connector which I belive are responsible. I drew in a white line where the white wire connects, as the other 3 are blue. I think that the white may be power or ground. I also circled in white where there's a white dot around the pin on the circuit board, maybe this will help. Now what's your advice from here? If you need a better pic, or one of more of the board, let me know.

[slickwillie]

oops, here's the pic:

[slickwillie]

ok, if this doesn't show up, i'll go crazy!

[msx-2]

you are probably still under moderation , ask a moderator if you can post a pic. (maybe ace can help)

[Tuga]

Ok, that surely looks like it.

The fact that they are facing opposite ways (just like mine) PROBABLY means 1 is for the “PowerOn” signal and the other for the “I’m PoweredOn” return signal.

You gonna need to grab a meter and do a few things but

First:
Do not power the Projector with the PSU opened. Lethal voltages inside.

Second:
Read the safety warnings on my previous post.

Third:
I take no responsibility of any damages done to your projector or to yourself.


Now we can continue, lol

Draw 2 optos on a paper and try to complete the circuit around them.
Have a look at my drawing and try to compare.

1- Find out which wire is connected where exactly (the 4 of them).

2- Find out which wire is ground. This will be connected to both Optos on the same side as the connector. To do it, reconnect the wires to the main board and check for continuity between mainboard ground and the pins on the optos.
Don’t use the PSU ground since they should be different grounds. This is the main objective when using OptoISOLATORS.

Or if you have a meter that can test Diodes, with the Projet switched off, put the RED probe on the pin marked with the white dot and the BLACK probe on the other pin on the same side of the component. If it reads approx. 1V the Black is Ground.
If it reads 2.999, The RED is ground, (but I doubt this is the case)


3- Find out which one is pulled High (+5V) when you press “PowerOn” – this should be the one that connects via a small resistor (to the white dot Pin), since you can’t put 5V straight to the Opto.
You can check this on the main board side. It is easier and since you will have to power the projector to be 100% sure, it’s definitely safer to do it on the main board.


4- Find out which one is always High, (+5V) and maybe needs to be pulled low.

5 - And what is the extra wire and where does it connect to?

Once you have done this, and drawn a circuit, post it here and we can discuss the next step.





PS: Mathias have you found your OPTOS yet????

[Tuga]

OOPS! Forgot the PIC...

[msx-2]

someone in another topic said that on avs forum they were trying to replace a UHP lamp (=a small gap metal hallide) with a new one . By that i mean the small lamp part in a lamp module of a projector. And the price of a 120 or 150 watt lamp would be around 40 bucks. Does anyone know where i can find more information about this?