Quote Originally Posted by mackrackit View Post
Do you have pin #3 on the display going to a pot as a voltage divider for contrast?
You have 100% good question !!!!
When I was use 2x16chr display it have bad contrast and I was see TEST on it,but 4x20 have extra contrast and with same value all poligons are black at these oment I was reduce fix resistors on network on pin 3 and problem go out I can look normaly and 4x20 work fine.

The best thing is have mentors out of personal laboratory !
Other can find what you cant in your project ;-)).

The best regards to all