How do I bypass this projector lamp board??

How do I bypass this projector lamp board??
Posted by azigta on 20 Sep, 2014 03:16
Hi, I´ve got an Epson EB-1900 projector. I got it for free because the lamp was dead. I´ve been reading on the manual and it seems to be a way to reset the lamp hour counter. You just go through the menu and select reset lamp hour option and there you go.

For what i´ve read, it looks like you can install non-official lamps. I mean, compatible lamps for this projector. This projector uses a 76v 230w lamp (yes, 76v 230w, I didn´t mean 230v 76w. It´s a weird voltage isn´t it?) So tecnically you install the non official lamp after your lamp has gone and then go to that menu and select the reset counter.

So I thought "Why not install a 100w led in it?" So I installed it and for my surprise, It works better than spected, it fits in the lamp´s original enclosure and aligns perfectly to the structure!

But sadly, after the projector does it´s "warming" procedure (the power led blinks) It shows the bad lamp sign on the leds (looked it up on the manual, it´s clearly a bad lamp indicator not any other thing). After some minutes it turns off. After the warming procedure it should go to the "input" message and then I should be able to go to the menu and reset the lamp time. But I guess installing another lamp with external power supply doesn´t work for this thing. I think It should have something connected to that 76v output to simulate that there´s a lamp installed.

So, knowing that the lamp it´s 76v 230w (halogen) How much should be the resistance required to emulate the lamp´s power consumption? Also, How many watts will the resistor needed?

I think there is no chance to convert those 76Vac into 36Vdc for the led because of the room there. It´s very small, There is no room for a bridge rectifier and a 110vdc to 36vdc converter. So I think fooling the projector with a dummy load resistor should do the job. It´s kind of annoying because the power consumption will be more than with the original lamp. But well, I had this led lying around and I finnaly used it for something cool xD

Hope you can help me guys. Thanks

EDIT: After a lot of searching and testing I did only discover that is possible to bypass this circuit by doing a bridge in some optocouplers. It seems that the ballast of this projector it´s the same that a lot of other projectors but I don´t know where do I have to make the bridge. I put a photo of the lamp controller board.

https://www.dropbox.com/s/67gj7idnkp15doc/20140920_183429.jpg

I did the bridge on pins 3 and 4 of all the optocouplers, nothing. Red Lights error appears... Where do I have to make the bridge? does anyone know?

#1 Reply
Posted by Kjelt on 20 Sep, 2014 13:56
Ok first off all chances are 95+% that the original lamp is NOT a halogen lamp but a special kind of HID (high intensity discharge) lamp.

Then first the bad news: if it is an HID lamp than you can not simply place a dummy load on the ballast to fool it that there is a lamp attached unless the firmware of the ballast has this programmed in its code for testing purposes (sort of factory debug / testing mode).
In normal mode, the ballast will first ignite the HID lamp by applying a 1kV to 2kV ignition voltage (sweeps up till ignition) then it monitors the voltage and current (and thus power) over time of the lamp to see if it is still within specification (the older the lamp the higher the end voltage). If the voltage or current go anywhere outside the OK window for any amount of time, the ballast will shut down (this is necessary since HID lamp can explode if operated outside the safe parameters.
So with a resistor the software in the ballast will pretty soon see it is not valid lamp (the ignition voltage for one is never reached since with a resistor you can not sweep up the voltage), then the voltage and current will stay steady from first second on (no ramp up) and conclude the lamp is outof spec, shutdown and report an error to the projector firmware.

Then the good news: the error reporting in old projectors was a simple high/low signal, in newer projectors it is some sort of protocol and if you know the protocol between the projector firmware and the ballast firmware you can replace the whole ballast electronics with your own microcontroller that only has to mimic the original ballast protocol than all is OK. Bad news here is that you must see to obtain the protocol.

#2 Reply
Posted by azigta on 20 Sep, 2014 14:40
Okey, time ago I did somerhing on a DLP projector, it was about shorting an optocoupler to send the motherboard a logical 1 instead of a 0. It worked, the projector admitted all kinds of lamps.

I think I'm going to try looking for an specific optocoupler on the ballast module and see if I can short it to make the system believe that it's ok . I'll come back and tell

Thanks

#3 Reply
Posted by azigta on 20 Sep, 2014 16:49
Ok, I opened the projector and one by one I shorted pins 3 and 4 of the optocouplers and it gives me 3 red lights wich according to the manual it means death. So I got it like it was at the beginning.

Does anyone know where´s the trick on this model? I´ve seen a lot of projectors on internet with the same issue and by shorting one of the 3 optocouplers it works.. Mine doesn´t ..

#4 Reply
Posted by azigta on 20 Sep, 2014 20:39
Quote from: Kjelt on 20 Sep, 2014 13:56
So with a resistor the software in the ballast will pretty soon see it is not valid lamp (the ignition voltage for one is never reached since with a resistor you can not sweep up the voltage), then the voltage and current will stay steady from first second on (no ramp up) and conclude the lamp is outof spec, shutdown and report an error to the projector firmware.

Hey, I just thought about that words... This projector stopped working because the lamp exploded. So that could mean that they resetted the counter without replacing the lamp and that made the lamp explode.

Also, the cables for the lamp power supply aren´t made to stand 1 or 2kv As they are not high voltage cables, they are just normal cables. So that makes me think this is not an Hi density lamp. What do you think? Should I try putting a dummy load?

does anyone know the value for that resistor?

EDIT: Added info on principal post. It´s definitely not HID, and the ballast its common but I don´t manage to make the bridge on the optocouplers.

#5 Reply
Posted by kxenos on 20 Sep, 2014 22:41
You will need 25.12Ohms, 230W resistor to simulate this. Good luck with your project.

#6 Reply
Posted by azigta on 20 Sep, 2014 22:57
Quote from: kxenos on 20 Sep, 2014 22:41
You will need 25.12Ohms, 230W resistor to simulate this. Good luck with your project.

I´m not going to put a resistor xD I discovered that hacking the ballast I can solve the problem xD Now I´m trying to discover a way to do it... xD

#7 Reply
Posted by amyk on 21 Sep, 2014 10:51
Some pictures of (both sides) of the relevant boards would be appreciated.

#8 Reply
Posted by Kjelt on 21 Sep, 2014 12:34
Quote from: azigta on 20 Sep, 2014 20:39
Hey, I just thought about that words... This projector stopped working because the lamp exploded. So that could mean that they resetted the counter without replacing the lamp and that made the lamp explode.
Normally the firmware would stop before any risk to the lamp, that said I have seen often that due to the enormous heat some sideeffects happen on the burnerglass like on a JVC projector the plastick of the lampholder could not handle the extreme heat and in the first hundred hours produced a bit of smoke that stuck to the burnerglass. That made that the place where the smoke attached to the glass heated up much more then the other part of the glass resulting in a bursting of the glass, aka explosion of the lamp.
With a normal aging lamp the burning voltage goes up (takes some time to runup after ignition) and the firmware just shuts down above a certain voltage, aka EOL end of life (of the lamp).

#9 Reply
Posted by azigta on 21 Sep, 2014 21:50
Hi, I´ve been looking on internet and seems like the 5 pin cable going out of the lamp it´s a pain in the ass. In some projectors , you have to ground a pin and there you go, in some other you have to put a bit of solder in an optocouplers photo transistor pins. This projector doesn´t seem to be one of those.

Some guy in a forum that has an epson projector too , did some magic and found that putting a resistor between cables 3 and 4 and also between 3 and 5 and grounding the 1st cable made it stay on. I asked him, i´m waiting for an answer

I tried with the same values but as it was a different model, it didn´t work. As spected.

I asked that user what formula did he use to know what resistor to put on those cables.

If I end up finding a solution to this problem I´ll post it but for now i´m a bit out of hope so I assembled the projector back on and let it on a shelve xD.

Anyway thank you guys!

#10 Reply
Posted by poot36 on 22 Sep, 2014 06:30
If you can find a service manual for this projector (search the model number and the words service manual), you will hopefully get the schematic for the entire projector including the lamp controler and from there you should be able to figure out what type of signals the lamp controler ic is sending out through the opto couplers by looking at the ic's datasheet. If you can find the lamp controler ic on the projectors circuit board you should be able to find the datasheet as long as the part is not rebranded or under a NDA agreement. If you have a oscilloscope or logic analyzer you can try probing the signals on the LED side of the opto couplers and try using a 120V 200 - 250 Watt light bulb as a load to see if that will trick the projector into staying on long enough to get the data signals out of the lamp controler ic so that you could replicate them with a microcontroler. Good luck.