Hello:
I am having a problem viewing the display on an Optrex 20171 LCD unit. Not sure of the model, but markings on back are "PWB20171-CEM" and date code is "8955M4". I have data sheet for DMC20171 that seems correct but not sure this is the same unit. Has 3 chips on board 1- HD44780A and 2 HD44100H that match data sheet.
Problem is I can only see display if I view it by tilting and look into it from the bottom edge. My contrast control is a 10K center wiper volume control pot tied between the +5V and ground supply to board. I see voltage vary at pin 3 when I rotate pot and display is only visible at max contrast setting. Board does not appear to have either LED or EL backlighting.
Question: do I need to increase the contrast more? I am using a PC power suply for my project, so I have -5V available. Can I wire the contrast control to -5 thru the pot? Would that help?
Any suggestions appreciated.
Dialtone
I am having a problem viewing the display on an Optrex 20171 LCD unit. Not sure of the model, but markings on back are "PWB20171-CEM" and date code is "8955M4". I have data sheet for DMC20171 that seems correct but not sure this is the same unit. Has 3 chips on board 1- HD44780A and 2 HD44100H that match data sheet.
Problem is I can only see display if I view it by tilting and look into it from the bottom edge. My contrast control is a 10K center wiper volume control pot tied between the +5V and ground supply to board. I see voltage vary at pin 3 when I rotate pot and display is only visible at max contrast setting. Board does not appear to have either LED or EL backlighting.
Question: do I need to increase the contrast more? I am using a PC power suply for my project, so I have -5V available. Can I wire the contrast control to -5 thru the pot? Would that help?
Any suggestions appreciated.
Dialtone