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  1. #1
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    What would backlight voltage likely be for PWB 20434-CEM ?

    I have several 20x40 LCDs I'm playing with and just noticed some have what has to be a backlight.

    I had thought they had none ... so am pleased. I can't find any data on these and am not sure what the backlight voltage would be.

    The LCDs are labeled with the number: PWB 20434-CEM. They have a single line of 14 pins ( I know the pinout for that) and then 2 pads soldered to the backlight. I tried poking around with an ohmmeter to see if it might be similar to an LED and it does not appear to be.

    Any idea on what the backlight voltage/current might be ?

    Would appreciate any advice.

    •   Alt16th July 2017, 23:26

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    Re: What would backlight voltage likely be for PWB 20434-CEM ?

    Normally, the displays with 14 pins do not have a backlight and the Optrex data sheet says it doesn't have one either. Ones with a backlight have an extra pin 15 and 16 to supply it. However, the PCBs are usually made with provision to fit a backlight as an option so perhaps the pads you see are for that but not actually used.

    The backlights are typically either electroluminescent (~100V AC) or more commonly LED in which case it will be a single white or green LED needing around 5V but you might have to externally limit it's current to around 10mA or less.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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