Wow, 1.4 has been discontinued a long time ago and I have to remind myself how the contrast works on this version. If I recall correctly, 1.4 uses a resistor voltage divider to create the voltage that controls contrast. It’s possible that you may have soldered the wrong resistor — according to the instructions (http://rayshobby.net/opensprinkler/svc-build/opensprinkler-v1-4-build-instructions/) RLED is a 100 ohm resistor. Please confirm this is the case. If you soldered a different resistor to RLED, that will create the wrong voltage for contrast.