Author Topic: Poor legibility on NHD-0224WH-ATDI-JT  (Read 196 times)

Alnitak

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Poor legibility on NHD-0224WH-ATDI-JT
« on: January 24, 2019, 05:24:46 PM »
I've just installed a white-on-black LCD in an old synth, but the legibility is very poor.

Is this indicative of too bright a backlight, or poor contrast settings?    Only the very top of the unit's (software controlled) range of settings is even remotely usable.

I already put a 50R resistor in the backlight cable, on the basis of 3.5V forward LED voltage at 32mA.  If it is simply that the backlight is too bright, I'd rather not remake that cable.   I noticed there's a 0R 1206 resistor on the back of the display that looks like it might be in the backlight circuit.  Is that so?    I do have the necessary equipment and components to drop extra resistance in there if required.
« Last Edit: January 24, 2019, 05:27:45 PM by Alnitak »

Ted_M

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Re: Poor legibility on NHD-0224WH-ATDI-JT
« Reply #1 on: January 29, 2019, 09:13:40 AM »
Hi Alnitak,

Assuming your source voltage is 5.0V to the LED, the 50 ohm resistor is the correct value to achieve a 30mA current source for the LED.

Looking at the angles of the pictures taken in the post, they are at or beyond the rated viewing angles of this display. 

The 12:00 viewing angle (top view) is rated to 30 and the 6:00 viewing angle (bottom view) is rated for 60.  Beyond these angles the contrast will not be optimal.

We suggest setting the contrast voltage applied to pin 3 of this display to provide the best contrast at the desired viewing angle.

Best Regards,