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Thread: Running the XJ-A140 With Missing Diodes

  1. #11
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    May 2009
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    UCSB
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    This projector does not have any color balance settings, all tests so far have been done with the red source at full power.

    I was tempted to try adjusting the color balance from my computer (most modern video cards have support to do this) but honestly it is good enough as it is. it just gives the video a nice warm feel

  2. #12
    Join Date
    Jan 2007
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    Anaheim, CA
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    After you guys finish putting them back together.. Anyone have any projectors they might want to sell me? Preferably in the US.

    - instinct

  3. #13
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    Dec 2006
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    Germany
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    Quote Originally Posted by krazer View Post
    This projector does not have any color balance settings, all tests so far have been done with the red source at full power.
    The projectors normally have a colour balance. But AFAIK this is only active in Economy mode ECO1 or ECO2.

    Joachim
    Producer of EasyLase USB and NetLase
    Lasershow software DYNAMICS

  4. #14
    Join Date
    Aug 2010
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    Seattle, WA USA
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    Curious if anybody has experimented with alternate blue light sources? I've seen 20W and larger multichip blue power LEDs which electrically speaking ought to be a drop in replacement for each string of laser diodes. Obviously the optical performance would be inferior but if the projector is usable with only 6 LDs installed perhaps this would work ok? I bought an A140 to strip the lasers from and had intended to take the whole thing apart for the other bits & pieces but I'm thinking of using it as a testbed for other experiments instead.

  5. #15
    Join Date
    Jul 2005
    Location
    Kansas City
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    209

    Default THANKS

    Thanks so much for the information on this. It worked great. I took out 8 diodes as I really only needed 6 and got back together and it looks just about the same as before. I had really waiting to tear this apart because I hated to have a useless projector for only needing so few diodes.
    Thanks again for all of your hard work.

  6. #16
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    May 2009
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    UCSB
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    Glad to hear that you were successful!

    I am sorry to those who have contacted me on/off the board, school has taken up way more time that I had hoped.

    I will get it figured out eventually...

  7. #17
    Join Date
    May 2008
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    nerdtown, USA
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    1,165

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    It seems like it would be probable that the red LED drive waveform is derived from an SMbus (actually i2c) controlled chip. In which case, dimming the red LED would be doable by using a microcontroller (say, a tinyAVR or PIC) to inject new signals. Since i2c is an open collector bus, this is safe and easy.

    What chips are in the LED drive section?

  8. #18
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    The waveform is controlled over a serial connection (call it what you want, I2C, smbus, etc they are all the same thing), and yes it should be possible to intercept this signal to adjust the LED brightness. The tricky part is that there is a fair amount of logic on the driver board, and without access to the firmware in the microprocessor or clpd it will take a lot of time with the logic analyzer to trick the projector into doing anything useful. There is one hope however, if you look carefully in the TI DLP documentation, the DLPC200 (this is not the exact chip used in the xj series, but it is the closest I could find) there is a documented LED serial interface, which is used to control your LED driver. if this is actually in use, its documentation could prove invaluable.

    The fan controller board is a little easier, it is also controlled over serial by well documented fan controller chip, so one could probably hack together a microprocessor to turn the fans down without heroic efforts.

    I have documented most of the chips in the projector in a text file linked my previous posts, linked for clarity again here The items with a star next to the part number I have located datasheets for, so if you can't find it pm me and I will see what I can do.

    I also have uploaded an x-ray of the driver board and motherboard in the '445nm Diode Info' thread (post 100) mirrored here

  9. #19
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    Apr 2006
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    Miami, FL
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    I wonder if you could just put 6 diodes or LED's in series to emulate a string of laser diodes?

    would be cool to remove 18 diodes from a projector and still have a usable projector

  10. #20
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    Apr 2006
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    Miami, FL
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    just curious to hear if you ever make any progress on getting it to fire up without using resistors to reduce the power consumption?

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