@Paul__B, Floresta and JohnK75.
My first experience ever with Arduinos was with the gear included in the official Arduino Starter Kit (Arduino Starter Kit Multi-language). This kit included a booklet that introduces the ultimate greenhorn I was at that time in the wonderful and colorful world of electronic gadgets. The booklet, “Arduino Projects Book” (second edition; note: the OFFICIAL booklet, with Massimo Banzi in the Advisory board, and reviewed by Tom Igoe) features a project # 11, ‘Crystal Ball’ that describes how one should connect a 16x2 LCD display to an Arduino: "Place the potentiometer on the breadboard, connecting one end pin to power and the other to ground. The center pin should connect to V0 on the LCD. This will allow you to change the contrast of the screen".
So far so good. Method 1 is pot meter wiper to pin 3 on the LCD display. Remaining pins of the pot meter to 5V and GND. Blessed by the supreme authorities.
Method 2 is pot meter wiper to to pin 3 on the LCD display, one of the remaining pins to GND. See corrected illustration in the project in How to display Arduino sensor data on a ‘classic’ lcd display – thesolaruniverse
updated my illustrations - thanks for your comments):
Method 3. Resistor between pin 3 of the LCD display and GND. Determine experimentally how much resistance you need. In the case of my own LCD the optimal resistance is 470 Ohm. An article on Circuits4you suggests 1k (16×2 LCD interface with Arduino UNO | Circuits4you.com).
Method 4. The software pin resistor solution. Suggested by Somtips (Connect Arduino LCD without Potentiometer Register & I2C - Som Tips): pin 6 of the Arduino to pin 3 of the LCD display.
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
// and so forth
This did not work with my Arduino nano- lcd display.
In conclusion: if your lcd display does not work: 1. Check the sketch, 2. Check the wiring, 3. Check all the pins, 4. Check the breadboard, 5. Replace all the wires, 6. Check the pot meter, 7, connect lcd display to another Arduino, 7, connect another lcd display to your Arduino, 8, ask the guys at Arduino Forum, 9, solder everyting firmly together, 10, buy another lcd.
Finally: when you are desperate: remember “if all else fails, read the manual”.
- thanks for your comments. This is a great forum.