userHead Account cancelled 2020-10-15 10:53:30 891 Views2 Replies
It seems that the "backlight on but no characters displayed" is a common issue with this unit

After modifying the LCD_I2C library and searching the net for several hours and testing other possible solutions, I traced the issue (at least in this case) to the 5v line from Arduino, it is not stable when using the USB as the power supply (it can provide less than 5v if the power supply is not at least 6v) and will output 500mA only (at the best)

You might test if this is your case, by changing the setup to a single line lcd mode, as this needs less power the first line characters might become just visible

(This is why there are several posts on different forums of only the first line "blocks" visible when setting it to the highest contrast)

After I changed to an external 12v power supply (and set the pot to the highest contrast), the LCD became really bright with really visible white chars
2020-11-10 11:57:37 I think it's because of insufficient power supply. Changing external power supply also works in my case

Brian from
userHeadPic quanghunghim
2020-11-10 10:27:34 Probably the reason for the insufficient power supply, because the USB interface of the computer may not reach the 5V voltage userHeadPic 347945801