I have had it for a long time but had not set it up until the other day at which point it was working totally fine- backlight, RS232 communication, software(LCD Smartie) all functioning.
Then I switched the power supply from a big variable one to a wall-wart outputting 9V at 500mA. I had it working with this briefly but after rerouting the cables all I get are solid black characters without any backlighting.
What might I be doing wrong? I seem to remember having this problem when I was using the variable psu but I don't remember what the problem had been. Switching back to the variable supply now yields the same thing.
This is crazy-frustrating

Thank you in advance for any ideas you may have.