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How can I do this - LCD to DSUB connection

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  • How can I do this - LCD to DSUB connection

    I have a problem at work that I'm trying to solve. On one of our CNC lathes, the CRT monitor went out, and it's going to cost over $800 to get it fixed, or even more if we get a brand new one. We are able to run the machine right now because we connected a regular ol' CRT computer monitor to the back of the machine. I done some searching on ebay and found several people selling old laptop LCD monitors for like $20. The machine needs like a ~12" monitor... maybe 13" but that'll be pushing it. I have a DSUB connection on the back of the machine for an external monitor. My question is, would it be possible to buy one of those cheap LCD laptop monitors and somehow connect it to the machine via a DSUB connector?

    Thanks for your help,
    My Project Progress

    Progress [|||||||---] = 70%

  • #2
    Hi Justin,

    The simple answer is: No.

    The more complex answer is: Perhaps.

    Most laptop LCD screens require a TTL or LVDS input with specific signal timings. The laptop's motherboard provides this output and the signal timing is often matched to the LCD panel the manufacturer uses for that laptop. Thus there is no way to directly connect a bare LCD panel to a standard DB15 VGA analog connector. The signals sent out on the VGA port simply do not match what the LCD panel expects as an input signal.

    That said, several companies make VGA to TTL/LVDS converter cards. These allow you to hook up a standard LVDS or TTL based LCD panel to your VGA port by converting the analog VGA signal to the digital signal required by the LCD screen. All of the LCD monitors you see that support VGA input have one of these converter boards inside the monitor case.

    Alternatively, many industrial PC's built for embedded computing have TTL and/or LVDS support directly on the motherboard. The motherboard of your CNC lathe controller may or may not have this support built in. If the lathe controller is relatively new, then it's possible that the support is built in. However, these types of motherboards usually have a BIOS setting that enables or disables LCD support. Furthermore, the BIOS may or may not support the specific signal timing for the chosen LCD panel. The manufacturer usually provides a list of LCD panels that have been tested and known to work with the specific motherboard.

    My CNC tabletop lathe is completely home-brew and uses a VIA Mini-ITX M10000 motherboard, so I know that it doesn't support LCD panels natively. If your lathe is a large, commercial type like an older model Fanuc, then I would suspect that it doesn't support LCD panels natively either.

    Your best bet would be to find a consumer grade LCD monitor at Best-Buy or the like. You could then remove the casing and use the LCD panel and its built-in VGA->LCD converter board.