I have qapass 1602a LCD screen i was playing with. But then the screen seemed to stop working. i connected it to a new breadboard power supply but all that changed is that you can see the squares, No backlight on. Please help!
It sounds like you fried it. Nothing was posted for me to see. Try adjusting the contrast control and measure your voltages to be sure they are correct and no more then 5 Volts. If you are using an I2C adapter check the address of it and be sure it is correct. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
god am i dumb, it's not broken, the anode and cathode wires were placed incorrectly. i am a noob at this sorry.
Hello, noob here. I ordered an Elegoo Most complete starter kit of amazon yesterday. Many projects went well. But for hours I've been trying to get my LCD screen to show something. The best i did once was that it displayed the text but it was mirrored(?). Right now all it does is change the background color when i upload the code. But anyway, I would like to know a few things like.
-What type of pot(entiometer) do I use and was setting to i put it in?
-What code should i try?
- Is it a driver problem? i Downloaded the Library.
And if an experienced arduino enthusiast may guide me though? Big thanks! 
Setup:
Code: modified 7 Nov 2016
by Arturo Guadalupi
This example code is in the public domain.
http://www.arduino.cc/en/Tutorial/LiquidCrystalHelloWorld
*/
// include the library code:
#include <LiquidCrystal.h>
// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
LiquidCrystal lcd(1,2,4,5,6,7);
void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello, world!");
}
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
}
LiquidCrystal lcd(1,2,4,5,6,7);
What Arduino board are you using? On most Arduino Boards pin 1 is the hardware serial TX pin. Try with a different pin.
What type of pot(entiometer) do I use and was setting to i put it in?
A 1K resistor from LCD pin 3 (Vo or contrast) give a good contrast on most of the LCDs that I have used. If you use a pot (5K, 10K or more, it really does not matter much) connect the wiper to LCD pin 3 and ONE end of the pot to ground. Do not connect the other end of the pot to Vcc. Adjust to taste.
Make sure that the RW pin (LCD pin 5 is wired to ground.
I slightly modified your code (changed from pin 1 to pin 8 and added delays) and uploaded to my Uno with 16x2 LCD. Wire the LCD as shown in the constructor (LiquidCrystal lcd(2, 4, 5, 6, 7, 8);). Or change the wiring and constructor to suit.
The following code works well.
// include the library code:
#include <LiquidCrystal.h>
// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
LiquidCrystal lcd(2, 4, 5, 6, 7, 8);
void setup()
{
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
// Print a message to the LCD.
lcd.print("hello, world!");
delay(5000);
}
void loop()
{
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 1);
// print the number of seconds since reset:
lcd.print(millis() / 1000);
delay(1000);
}
I'll try it. Thanks!
Alright, no characters appear but there's a blinking cursor. maybe show me a picture or a diagram? thanks. (I'm a very dumb noob. Beginner C++ coder)
Please attach a photo of your display and the wiring to the Arduino.
Using pin 0 or 1 - the serial interface pins - is an obvious blunder. Just do not ever use them!
Do not attempt to attach images from your Yahoo mailbox. You can upload the image to the forum and then modify your posting to use the upload link as the address of an image. You can even modify your first post above to do that. 
TOPIC MERGED.
You may want to READ THIS for future reference.
It will help you get the best out of the forum.
Bob.
I found out i just had to follow the elegoo tutorial #22 which I stupidly put in the corner and thought it was useless, but thanks to those who gave up time trying to help a dumb noob!
I find it insanely funny that they wrote QA PASS directly on the silkscreen of the PCB. "QAPASS" isn't the manufacturer at all. It's just a super lazy way to save a sticker and automatically say that everything passed the test, without even being tested anyway :o
// Per.