EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: franciscoPT on February 04, 2021, 08:14:24 pm
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Hi guys, im building a power supply with 2ch 0-30v 0-5A, i have bought 2 lcd 20x4 2 years ago and test them when they arrived and they were working properly, today i was going to use them for the power supply and when i tried the typical hello world program, they didnt write anything, im using the arduino to controll them, i start check for shorts, with multimeter, on the solder pins, and found pin 5 and 6 are shorted, not on the solder, probably internal short, i check the other lcd and same thing, is this the problem?? can someone with same lcd confirm this??? is there any reason for shorting this 2 pins while soldering, thinking on that i try to be very careful and quick.
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Pin #5 is "R/W" and pin #6 "E". To send a command or data to the controller R/W is pulled down to indicate a write operation, and E needs a pulse to take in the command/data. A short between both pins would prevent the enable pulse, i.e. the display won't do anything. Is the short on the LCD module (desoldered/disconnected)?
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The facts that they were working when received and that both units behave the same now, suggest some wiring error on your part.
Are you for example identifying the pin numbers correctly? Maybe what you think is pin 1 isn't due to the way you have oriented the module.
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Im shure pin 5 and 6 are shorted, but its strange that they are on both lcd, i dont understand why and the bigger problem its they are not in the solder like bridge on pins, there is internal short wich i probably cant fix, i think i kill my lcd....
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Before I would pronounce the LCD as 'dead', I would try a standard Arduino Sketch that is known to work. Like:
https://www.arduino.cc/en/Tutorial/LibraryExamples/HelloWorld (https://www.arduino.cc/en/Tutorial/LibraryExamples/HelloWorld)
If you have already tried this kind of test then maybe the LCD is dead.