Hi all,
I'm looking for some help and advice on bypassing the lamp on an Infocus LP350 DLP projector.
I got this used with no bulb, and for my application I just need the DLP and driver circuitry, so I want to strip out everything else but still have it power up.
Right now, the color wheel spins and fans power up, then it makes a sound which I believe is the HV ignition pulse for the lamp. This repeats several times, then the power light begins blinking orange. In this mode, the DLP never activates.
I've found an optocoupler which I believe is the lamp sensor. It is normally at 0V on the input side, but spikes to ~1 volt when the ignition fires.
When I pull the input high with a 50 ohm resistor, the ignition pulse is not heard, but the DLP resets and shows a blank image.
However, I still cannot get anything to be displayed on the DLP.
I believe the problem may be that there is a photosensor underneath a yellow filter in the light tunnel, after the color wheel, I suppose to give an indication of the wheel speed.
I've tried shining a flashlight through the wheel, but this doesn't seem to have any effect, maybe because it's not intense enough?
Does anyone have more information on this projector, or any general ideas/advice?
thanks in advance,
baniel
I'm looking for some help and advice on bypassing the lamp on an Infocus LP350 DLP projector.
I got this used with no bulb, and for my application I just need the DLP and driver circuitry, so I want to strip out everything else but still have it power up.
Right now, the color wheel spins and fans power up, then it makes a sound which I believe is the HV ignition pulse for the lamp. This repeats several times, then the power light begins blinking orange. In this mode, the DLP never activates.
I've found an optocoupler which I believe is the lamp sensor. It is normally at 0V on the input side, but spikes to ~1 volt when the ignition fires.
When I pull the input high with a 50 ohm resistor, the ignition pulse is not heard, but the DLP resets and shows a blank image.
However, I still cannot get anything to be displayed on the DLP.
I believe the problem may be that there is a photosensor underneath a yellow filter in the light tunnel, after the color wheel, I suppose to give an indication of the wheel speed.
I've tried shining a flashlight through the wheel, but this doesn't seem to have any effect, maybe because it's not intense enough?
Does anyone have more information on this projector, or any general ideas/advice?
thanks in advance,
baniel
The noise you hear is usually the colour wheel spinning up and not the ignition. I think the sensor you are talking about is not for the colour wheel speed but instead for the position of the coloured segments. Try shining a light down the tunnel and look inside the lens. If it is still dark/black, then the DMD has not been powered up yet and you are probably shorting the wrong optocoupler.
Hi Gizmotech, thanks for the reply.
I can actually hear/see several different things happening:
the color wheel starting up makes a loud whirring, followed by the fans spinning.
The noise I think might be an ignition pulse is a short 'chirp' sound (not coming from the speaker) which sounds similar to a camera flash charging, but only for a fraction of a second.
I have the DMD exposed right now, so I can see directly what is happening on it.
There are two optocouplers coming off the power supply board, by probing them I believe I have determined that one is monitoring the fans, and I assume the other is the lamp monitor.
Shorting it seems to cause the projector to lock up (LED indicators no longer respond to button presses), but tying it high causes all the pixels on the DMD to switch, and the power light stays green.
In this mode, the buttons (menu, standby) seem to be responsive, but no image ever appears on the DMD.
My current guess is that without the proper signal from the sensor below the light tunnel, the projector can't sync to the color wheel, so it doesn't know when to display each color frame and so shows nothing.
Does this seem reasonable to you?
I can actually hear/see several different things happening:
the color wheel starting up makes a loud whirring, followed by the fans spinning.
The noise I think might be an ignition pulse is a short 'chirp' sound (not coming from the speaker) which sounds similar to a camera flash charging, but only for a fraction of a second.
I have the DMD exposed right now, so I can see directly what is happening on it.
There are two optocouplers coming off the power supply board, by probing them I believe I have determined that one is monitoring the fans, and I assume the other is the lamp monitor.
Shorting it seems to cause the projector to lock up (LED indicators no longer respond to button presses), but tying it high causes all the pixels on the DMD to switch, and the power light stays green.
In this mode, the buttons (menu, standby) seem to be responsive, but no image ever appears on the DMD.
My current guess is that without the proper signal from the sensor below the light tunnel, the projector can't sync to the color wheel, so it doesn't know when to display each color frame and so shows nothing.
Does this seem reasonable to you?
Realized I was being stupid - there is no optocoupler for the fans, since they are driven off the logic board.
If anyone is interested, I believe that the correct assignment is:
optocoupler U4 = thermal sensor, case switch
optocoupler U5 = lamp ignition
drive pin 3 of both to 3.3V to enable projector.
By shining a very bright fiber optic illuminator through the color wheel I was able to get the DMD to start updating, so I think the next step will be to scope the photodiode and try to build a circuit to simulate the proper signals from it.
If anyone is interested, I believe that the correct assignment is:
optocoupler U4 = thermal sensor, case switch
optocoupler U5 = lamp ignition
drive pin 3 of both to 3.3V to enable projector.
By shining a very bright fiber optic illuminator through the color wheel I was able to get the DMD to start updating, so I think the next step will be to scope the photodiode and try to build a circuit to simulate the proper signals from it.
I havn't actually worked on that Infocus Model but most of DLP works the same way. To test these after bypass, you should not need any kind of input as you should at least get the infocus startup logo screen apearing, thus either way the Colour wheel would be synced automatically. The sensor just monitors the position, a bit like a TDC sensor on cars. It will only know the one position and the rest of the segments are calculated. In my personal opinion, you need to pay less attention to the colour wheel and more to the optocouplers.
Other than the 2 wires that goes to the lamp, there should be another connector which goes to the control board. One of those wires should show around +3V with the projector powered up without the lamp. Trace that particular wire to the associated optocoupler and short that. If that is not pssible, then just short that particular wire to ground anywhere on the chasis. If that does not do nothing, try any other wires on that connector which shows around +3V and so on.
The optocoupler you are to paying attention to at the moment is the lamp ignition. This is not that important. You need to find the lamp lit. The rest, such as the case switch/lamp cover switch can be shorted at the switch end. You seem to be having similar problems to those who trying to bypass the Infocus X1.
Other than the 2 wires that goes to the lamp, there should be another connector which goes to the control board. One of those wires should show around +3V with the projector powered up without the lamp. Trace that particular wire to the associated optocoupler and short that. If that is not pssible, then just short that particular wire to ground anywhere on the chasis. If that does not do nothing, try any other wires on that connector which shows around +3V and so on.
The optocoupler you are to paying attention to at the moment is the lamp ignition. This is not that important. You need to find the lamp lit. The rest, such as the case switch/lamp cover switch can be shorted at the switch end. You seem to be having similar problems to those who trying to bypass the Infocus X1.
did anyone figure out all the pin assignments yet
hi all, i also have an lp350.
just wondering if anyone has fully figured out the bypass before i try mine.
hi all, i also have an lp350.
just wondering if anyone has fully figured out the bypass before i try mine.
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