e-licktronic Forum

OK so I put the 1.2k resistor back in R694 and my LCD display works fine just a little dim. I'm beginning to think this was my mistake and I didn't have the contrast adjusted enough to see the characters. I'm guessing I just didn't think I had to adjust TM3 so much and the amount I was adjusting had no effect. I did have to adjust the contrast at TM3 a lot to get the characters to display. Hope this helps someone in the future. Thank you to everyone that came to the rescue.

No characters at all usually are an indication for a broken trace or a bad contact between display and Atmega1284P. At least that's what I experienced with two Nava's I had here for repair and what users report in the forum. Try the following: With your Nava turned on, tap against the display and the Atmega from the top and from the side without touching any pins.

Otherwise it might be as you say. With the 1.2k installed in the beginning you had to turn the trimmer a tad more to get a result, since the resistor reduces current and voltage. With a jumper installed, characters logically appear at an earlier point when turning the trimmer.