LS display not outputting or displaying video.

Potential Symptoms

  • Screen is blank
  • Screen is dim that it looks blank
  • SBC is outputting signal to a PC monitor

Environment

  • LS display
  • SBC( signal board computer)

Cause

  • Wrong input selected
  • No output from the SBC (single board computer)
  • Bad DVI cable
  • No voltage to the video card
  • bad power supply
  • incorrectly configured 
  • DMC (diagnostics management card)

Resolution

Tools needed.

Computer monitor

Keyboard that has USB end

Mouse with USB end

Multimeter

Common tools

Laptop with tight VNC or Ultra VNC installed.

  1. VNC into the SBC using tight VNC.
  2. Verify that DVS player is running by hitting the windows key and seeing that the command prompt tab is open, and chromium window is open.
  3. If not able to VNC into the SBC hook up monitor keyboard and mouse, verify that you see the desktop and the SBC is outputting to the monitor.
  4. If not outputting to monitor replace SBC.
  5. If replacing SBC, it’s still not outputting to monitor replace DVI cable.
  6. If SBC and DVI cable are good and outputting, but screen isn’t working look at the screen on the edges of it or back and see if you see the backlight on it will be a white glow.
  7. If backlight is on, then verify the input on the screen is set correctly by using the keypad on the back of the screen.
  8. If keypad isn’t opening the menu on LCD screen, then look at the LED indicator on the keypad it should be green or yellow if no lights then troubleshoot the voltage going to the video card.
  9. If backlight is off, look at the DMC card and verify its wired correctly and look at the LED lights to see if any are flashing or off lights to reference circled in below pic.

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What the LEDs mean on DMC card below table. LEDs should be on steady

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  1. Check points for the voltages on the LCD screen to check. Note reference sign schematic called out for contract your working on as the below may differ depending on screen being used. 

  1. If everything is wired correctly and voltages are good but no backlight on or visually displaying still, try a new DMC card.
  2. If all the voltages are correct from power supplies and backlight is on but no visual on screen from menu or SBC replace the video card.
  3. If new video card doesn’t fix it, then replace the LVDS/TFT cable between the screen and the video card.
  4. If screen still isn’t working, then replace the screen if all voltages and wiring have been confirmed wired correctly.

 

KB ID: 000029144

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