Notice that the contrast control (LCD pin 3), instead of using a typical 10K potentiometer, uses an LM334, which ensures a constant current of 200µA to ground (so the contrast does not need to be ...

The PCB provides a 16-pin header compatible with standard 16x2 LCD modules, and should fit many of them within the footprint of the board if the headers are soldered at the top of the module. Note ...

The issue: I'm not sure about the LCD module. I just saw the 2004A label on some old advertising pictures. On the linked pdf I've found (5) Control IC: SPLC780D. ... Melzi schematics, JP16 10-pin ...