So I have been working with some Hantronix HDM16216H-5 LCD's on a few of my projects using the 6wire half Byte mode and the included Arduino 18 LiquidCrystal library. I have two of these LCD's and have not had a problem with them.
I wanted a display with a back light so i ordered a few Hantronix HDM16216L-5 displays that have a yellow LED back light.
I assumed that because both displays are almost identical, pin compatible and use the HD44780 interface they would be easily swapped.
I got the displays soldered on some headers, swapped it into a breadboard and nothing.
I have tried switching to using full Byte communication and even the RW pin. I have swept the contrast input Vl from 0v to 5v. I have tried it with the back light wired in and not.
I don't get any quick flashes or random characters or boxes from the HDM16216L-5.
After reading some posts about the initialization problems with the older LCD libraries pre-Arduino 17, I switched to a HP bench supply and reset all power to the arduino board and LCD several times.
I have swapped in 4 of the HDM16216L-5 displays (none work) and two HDM16216H-5 displays (both work).
I am using the example sketch 'hello world' from liquidcrystal provided with Arduino 18.
I received the two HDM16216H-5 displays with some tekbot kits a few years ago. I ordered the HDM16216L-5 displays from mouser.
Is there some sort of initialization these displays need outside of the arduino liquidcrystal initialization when the displays are new?