I'm using the LCD4Bit library to interface with an LCD screen like this
I had it all working fine, with two lines being used on the LCD. I reverted to 1 line use of the LCD whilst running some test code, and now when I try to use the 2 line capabilities (that is, calling the LCD4Bit constructor with argument 2), the LCD is extremely dim. Now, it's pretty dim to begin with, and now it's barely visible. It is undetectable when plugged into my desktop, and just about visible when connected to my laptop. One line is just as bright as ever.
I'm wondering if some low level setting has been messed around with somewhere? I had a look through the library code but couldn't find any clues as to what the problem might be.
I've also tried with an external power source and the same phenomenon occurs. Does anyone have any suggestions as to why this might be happening? Perhaps the screen has been damaged... but with one line mode the top line is still bright, yet dim when 2 lines are used.
Typical that this happens the day before I need to do bit of a demo tomorrow! Hehe. Any help much appreciated.