[En-Nut-Discussion] Medianut 2.0d LCD Backlight Not Functional

[Harald Kipp]

Hi Tim,

On 5/27/2011 1:54 AM, x1 wrote:
> My assumption is R53 and R54 do not exist so if I solder resistors in R22
> and R23 nothing will short out and the LCD backlight command will work. Can
> anyone confirm this?

R53 and R54 are used for a custom hardware, where anode and cathode are
swapped. Either R22 and R23 _or_ R53 and R54 are mounted. R22 and R23
should work for you.

Btw. swapping pins 19 and 20 will typically not harm to the display, as
they are simply connected to one or more LEDs. And this is where the
trouble starts. In many displays several LEDs are connected in series,
and the forward voltage adds up. We have displays with 4 white LEDs in
series, each of them with a forward voltage of 3V! You'll need 12V to
get them lit. Medianut can provide 5V only.

Regards,

Harald