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I've connected the circuit as shown in https://www.arduino.cc/en/Tutorial/HelloWorld?from=Tutorial.LiquidCrystal and I ran the program, but I can't fix this problem:

the LCD seems not to respond correctly: the first row is black and for what concerns the elements of the second, they all have three top lines of pixel high and the others low..

I checked over and over if I made some mistake connecting wires but I haven't found any error..

Is the LCD broken according to you? How can I fix?

Here the photos of the circuit: https://drive.google.com/open?id=0B2h2zzEgtaqydElrRDVUNGVuWDA

  • Where's the sketch? – stevieb Aug 23 '17 at 0:36
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I looked the images you have on Google Drive. On the image called IMG_20170822_233722.jpg, I see you are using a 50k ohm potentiometer to control the display contrast. Normally you would use a 10k ohm potentiometer. Using the 50k will make the adjustment very sensitive and hard to adjust. If you are careful and adjust it slowly, it might work for you.

The other image, IMG_20170822_234242.jpg, clearly shows "poor solder joint" connections on the display. D4 - D6 (especially D5 to D6) look like they could be "shorted" together. I think you could fix them by using Desoldering braid or if you don't have any, you could heat up each connection with your soldering iron then quickly "flick" the display to remove the solder. After you have removed the excess solder from each connection, I strongly recommend applying soldering paste to the connections next. The soldering paste really helps the solder to flow into the connection. Now try re-soldering each connection. I'm not sure what kind of solder or iron you are using but I can tell you what works for me. 25 watt pencil tip soldering iron with 22 gauge / 0.71mm rosin core solder.

I can't tell for sure from the pictures if any of the display pins are shorted together and I don't know if shorting them together will damage the display, Arduino or both.

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Black first row suggests that the LCD is incorrectly initiated. That's often caused by wrong code or wrong hardware / connection.

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