Reprap 12864 LCD has no contrast

Hello!

I have lost contrast on my Reprapdiscount 12864 LCD display connected to my Ramps 1.4. I can see the graphics really really faint. Everything else works and I can navigate and drive the stepper motors on my CNC.

BUT! If I connect a ordinary USB cable to the Arduino Mega from my computer, I get contrast and everything is as normal... But not with my regular power cable adapter.

How do I fix this?

/ Oskar

Edited 1 time(s). Last edit at 12/09/2020 09:15AM by DailyBombs.

Your 5v voltage regulator on the mega is damaged. If you measure 5v when USB is disconnected you will probably read less than 5v.

Replace your mega. Preferably with a re-arm