Do you think the 5.3V from the buck converter is the culprit, or could something else be to blame?
Are the LCD's destroyed? It appears permanent from as it holds when I power it alone without input.
If the 5.3V is the issue, what is the best things I should do to overcome it. Is there something simple I can do like a voltage divider or just get a better quality buck converter.
If you are wondering, the reasoning for the buck converter is this device will be powering a 12v solenoid and has a flow meter and a LCD running of 5v, so I found this to be the cleanest way, that made sense to me, to have sufficient power at 12v and 5v.
There are some wires visible going to the right; what is connected? I suggest that you provide a schematic (photo of hand-drawn is fine) that shows all components and all power connections. It takes the guess work out.
Which exact Arduino are you using (I think it's a form of Nano). Which exact display are you using?
It looks like a h/w problem.
Which library are you using?
Can you post your test sketch?
I would be curious to see the results if you install the hd44780 library and run the included diagnostic to test the device.
You can the install the hd44780 from the IDE library manager.
And the sketch to run is the I2CexpDiag sketch from the hd44780_I2Cexp i/o class.
It will test the i2c signals, then the internal DDRAM of the display.
Test results are sent to the serial monitor.
Yeah i thought the same. The code was just the sample code reworked so here it is.
On the buck converter question, do you think 5.3V would do any damage to the display?
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,20,4); // set the LCD address to 0x27 for a 16 chars and 2 line display
void setup() {
lcd.init(); // initialize the lcd
// Print a message to the LCD.
lcd.backlight();
}
void loop() {
lcd.setCursor(0,0);
lcd.print("A:");
lcd.setCursor(0,1);
lcd.print("B:");
lcd.setCursor(4,0);
lcd.print("P:");
lcd.setCursor(4,1);
lcd.print("C:");
delay(100);
}
Hey, its 23C, its 12:43am and its Ballarat, very abnormal temperatures for 5 nights in a row.
Air Con is on fan only keeping the house cool with gentle fan.
We don't like having AC on cooling 24hrs, its evap type and even with a couple of windows open, I can still feel the humidity at times.
You cannot by definition use an evaporative cooler in a humid area. Don't know how humid Ballarat is, but I am greatly disturbed by Hardly Normal and such flogging evaporative coolers in coastal areas.
24.something° here, 70% humidity, less than 1 km from sea. Sitting with gentle fan and going (back) to bed shortly.
See 
Too much 
