My shield in duinotech XC-4454 2x16.
I've attached it to a Sainsmart UNO with the sketch below and it worked fine with good brightness.
Then, because I want to be using the Arduino without the shield actually pressed on, to free access to other pins, I reconnected it with jumpers, eyeballing the matching connections. I initially connected just D4-9 plus 5v, gnd and A0. I also experimentally connected other (matching I believe) pin with jumpers.
The display still works, i.e. gives the correct output w.r.t. button presses but the screen is very dim. I'm not sure the backlight is on at all.
I pressed the shield back onto the UNO and still dim. I connected a 9v supply - no change. I uploaded the sketch to a genuine Mega 2650 R3, pressed on the shield, and get the same result.
Is it possible/ likely I damaged the LCD (there is a transistor I read can be damaged?) by manually connecting pins?
// sketch 09-01 USB Message Board
// lcd(RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
int numRows = 2;
int numCols = 16;
int sensorPin = A0;
int boo = 0;
if (Serial.available() > 0)
char ch = Serial.read();
if (ch == '#')
else if (ch == '/')
// new line
boo = analogRead (sensorPin);