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changing the light source for the pico DLP kit

SA13071
Prodigy 220 points

The DLP pico projector has three LEDs as sources.  My application requires a different light source and optics, I have succesfully

removed the optics from one of my kits and remove the LEDs but the interface gets upset by this: a little red LED comes on next to the

power button and the chipset stops functioning - it won't process any input and it won't listen to the I2c bus.  Plugging the LEDs

back in fixes things but it is a nuisance because the LEDs are glued to the optical subsystem (which gets in the way) and are very

bright. I can disable them via the I2C bus but it would be nice if the pico projector could remember this - is there any way to:

 

Fix the settings so the DLP does not expect the LEDs to be present

and/or

Removed ot replace the LEDs with something else so that the project still functions.

 

Cheers,

 

SA

 

  • 0
    Intellectual 270 points

    Assuming the LEDs are constant-current driven, you may be able to get away with replacing them with 1N4001s, so the current is the same &the driver still seeing some load, but not dissipating too much power in the diodes.

    Obviously you could use zeners or resistors to give a comparable voltage drop to the LEDs, but you would probably need to heatsink them.

     

  • 0 in reply to Mike Harrison
    Prodigy 220 points

    That was the sort of thing I had in mind, I looked at the schematics and it actually looks like there is an input pin on the microcontroller the signals there is something wrong (next to an output which drives the red warning LED) I need to look at this more closely but I think it might be better to tie this high|low than change the LEDs.  Changing the LEDs would still require the attachment of their cable to the board which is a big pain.

     

    Cheers,

     

    SA

  • 0 in reply to SA13071
    Intellectual 270 points

    I had a glance at that - it may be the case that it is looking for a fairly tight voltage on the feedback pin to detect a LED overheating and shutdown before it cooks, but should be no harm in poking it with various voltage levels to see what happens...!

  • 0 in reply to Mike Harrison
    Prodigy 220 points

    Yes - it doesn't look like a simple 1/0 and is connected to a pin that can be configured as an A2D.  I am trying to get hold of the schematics (apparently available through the VARS but the one I contacted couldn't find them) so I can probe the boards.

  • 0 in reply to SA13071
    TI__Prodigy 450 points

    Hi,

     

     

    If you look at DLP® Pico MAIN-B SCHEMATIC document on www.dlpdiscovery.com (on the right side of the DLP® Pico Projector Kit page) there is a signal (LED_ANODE) that comes back to the MSP430 from the LED interface. When this signal is above 1 volt it detects that the LEDs are not connected.

     

    The schematic for the DLP® Pico DVI-B SCHEMATIC (which has the LED interface) can be found there also.

     

     

     

     

    Best regards

     

  • 0 in reply to tsolo
    Prodigy 220 points

    Thanks - it would be very useful to have the layout files for these boards -  the documentation at TI says these are available through the VARs - I contacted mine but they couldn't find the files - does anyone know where they can be got?

     

    "The Gerber files for the DLP® Pico Kit DMD control board layout are available to you through an authorized DLP®
    Discovery™ value-added reseller (VAR). A list of the VARs can be found at: www.dlpdiscovery.com/var. Please reference
    the file name above when contacting a VAR."

     

    TI2510515_00.L9552G001-B-Geber-DMDCONTROL-BOARD-FLC-03302009.zip

  • 0 in reply to SA13071
    TI__Prodigy 280 points

    Hi SA,

    I sent you a request to be my friend.  The DLP authorized VARs have the files you are referencing.  If you accept me as your friend, I can understand why you are being told otherwise as well as get you the information you need.  Thanks.

     

  • 0 in reply to GPark
    Prodigy 220 points

    I have successfully shorted LED_ANODE_0V_DETECT to ground (linked the capacitor from pin 28 of the MSP430 to the earth on mount

    of the JTAG (J112 I think).  It would have been easy to remove this cap and short the pads but the link is easily reversible.  The DLP

    functions fine now without the LEDs.

    Cheers SA