If R47 is correctly working the contrast of the display then the other issues can be the controller chip on the board IC2 (long chip in socket) or the data lines to the display
So back to basics
Check IC2 is in socket right way round
Check no pins bent (lift the chip slightly and make sure all pins are engaged in socket)
Check chip is fully seated in socket
Check solder joints on Socket (reheat to make sure)
Voltage VCC pin 7 (5v)
Voltage VCC PAD 7 (5v)
Is chip hot to touch (if yes likely dead)
Check solder joints 20mhx XTAL
The next thing is the socket for the display
Check joints both sides (main board and display board) for bridges and cold joints (reheat and resolder to make sure)
What test equipment do you have? Just a multimeter? Oscilloscope?
From: Wayne Robertson
Thank you; clear now.