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DMD stuck lines of vertical pixels???

Nick Conway
Prodigy 25 points

After exhaustively exercising my Discovery 4000 1080p board, I can't seems to get rid of stuck vertical lines of pixels (maybe a line every 50 pixels is stuck?  its unclear since I've yet to map my DMD to a camera and there are only lines on the right half of the display).  I've attempted to clean connectors etc and run all of the example modes (just from the control board) and displayed my own images over usb, but to no avail.  Any thoughts as to what this might be and how to unstick these pixels, or is the control/DMD board done for?

The lines appear off when I try to display a frame that is all on, 1's,  and  they appear on when I try to display a frame of 0's.  I can clear memory on the controller  and get the lines to disappear, but that's it.  Again, this occurs when I run my own code, default hardware code, and Discover Windows Evaluation software.

 

-Nick

  • 0
    TI__Intellectual 2265 points

    Nick,

    I'm sorry to hear about your trouble. I have a few questions that could help me understand your situation.

    Do you see the lines when you first turn on the board and the default pattern is running?  If so, it would seem to be an issue with the DMD, please send me a friend request and I can work with you to fix that issue.

    What frequency is your data input? The Discovery 4000 is recommeded to run below 320MHz.

    Please check the output of the DAD signals to make sure you are getting the correct voltages. The table below shows what these voltages need to be. If the voltages are not correct, the DMD will not work correctly.  

    Parameter

    Description

    Units

    DAD Output

    VRST_RAIL

    Reset Voltage

    Min

    V

    -26.5

    Nom

    V

    -26

    Max

    V

    -25.5

     

     

     

     

     

    VBIAS_RAIL

    Bias Voltage

    Min

    V

    22.5

    Max

    V

    26.5

     

     

     

     

     

    VOFF_RAIL

    Offset Voltage

    Min

    V

    8.25

    Nom

    V

    8.5

    Max

    V

    8.75

     

  • 0 in reply to WYA
    Prodigy 25 points

    I will check voltages as soon as possible, but right now I am merely updating static images while I try to resolve the problem.  The lines do exist when the default pattern is running. 

     

    -Nick

  • 0 in reply to Nick Conway
    Prodigy 60 points

    Nick,

    Vertical lines are often caused by a contact problem affecting a single data bit to the DMD. This could be in the interposer between the DMD and circuit board or in the flex cable. Do you see the vertical lines only on 1/2 of the display ? If yes I suspect this is the problem.

    Contact your VAR from which the board was purchased for more assistance in troubleshooting this problem.

     

     

  • 0 in reply to Nick Conway
    TI__Guru 54685 points

    Nick,

    I concur with JS.  Working with your supplier is the best way to resolve these types of issues. 

    First, you may want to simply reseat all cables and the DMD interposer by loosening the screws at each connection  and then retightening them.  First tighten them gently then alternate back and forth 1/4 turn on each screw until they are firm (but do not overtighten) - [similar to how you would tighten the lug nuts in a pattern when you change a tire]. 

    See if that cures the issue.