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Topic: LCD Display (20x2 DEM20231) - not even backlight :( (Read 85 times) previous topic - next topic

UdoVR

Chances will be slim but trying anyway:
Just bought an LCD display from my regular HW dealer. It came with the pins separate so I had to solder them on the circuit board of the display.

I think I did a good job (see pic) , checked bottom and top of the pins with multimeter and they are all ok.

According to the specs (https://www.display-elektronik.de/filter/DEM20231SYH-PY.pdf ) and based on the jumper settings (J2,J3,J4,J5) I should have PIN 16 as +5V (anode) and PIN 15 as ground (cathode).

At first I swapped them because I based myself on the starter kit version but not for long, AND it should normally be equiped with some light diodes to avoid damage, right? or at least not get damaged because of it... (it was only a minute or two before I noticed it).

I had everything connected (invl V0 via pot, RS, E, R/S to ground, VSS/VDD also connected) but the display stays dark.

Is there any other tests I can do to confirm it's dead?

Paul__B

OK, your photos to start with.








I think you need a series resistor for the LED - try 220 Ohms for starters.  Note that one row of the connector pins are the odd and the other row, the even numbers.

UdoVR

OUCH!!! beginner's mistake I hope? didn't notice the odd/even thing, also not in the documentation.

thanks a lot,Paul__B !   i have backlight now. now getting it to work!


Paul__B

#3
Dec 07, 2018, 10:13 pm Last Edit: Dec 07, 2018, 10:15 pm by Paul__B
OUCH!!! beginner's mistake I hope? didn't notice the odd/even thing, also not in the documentation.
Well, that's how it always goes with those connectors.  They go with ribbon cable and when that is connected, the numbers in the ribbon are sequential.

That module has "1" and "16" indicated, but did not tell you which "2" was, however the datasheet does in part 4.  :smiley-lol:

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