Hi all,
since some of you have had problems with their LCD-display, something good to know.
I have two new ones of LCD2004A. Both have integrated resistors for the backplane light.
See the red circle on the photo LCD2004: there are 51ohms (signed "510" on it), will say you can use it with the 5ohms series resistor on the board without any harm to the display. The producers have learned to enhance their products.
The old one I use at my controller has no series resistor. So an additional one on the board was necessary.
So TAKE A LOOK at yours and ACT CORRESPONDENT.
Visibility:
The contrast is set with with a small voltage at pin3 of the display unit. On our boards there is a 10k potentiometer as voltage divider which gives the possibility to find the best contrast by turning it. The aerea is very small, so turn SLOWLY. The contrast changes from "all blocks" are shown to "blank plane". You must find your individual point. Contrast also is changed by temperature, not a lot , but it does.
Hope it helps
73, Immo, DL5KB