LCD on Cohesion3D


I have a GLCG for ny Cohesion3D thats not working.

I have had trouble connecting it, But now i have power on The lcd at The screen i on (backlight).
But nothing appears on The screen

Anybody Can help?

Have you confirmed the cable is right? Not every vendor keys the IDC cable the same way, so you have to actually look at pin assignments and make sure it’s not in backwards. I’ve seen this (not with a cohesion3d board) before…


There is also a panel section of the config.txt file you might want to look at. Here’s the panel section from one of my older config.txt files:

## Panel
# See
# Please find your panel on the wiki and copy/paste the right configuration here
panel.enable                                 true             # Set to true to enable the panel code

# Example for reprap discount GLCD
# on glcd EXP1 is to left and EXP2 is to right, pin 1 is bottom left, pin 2 is top left etc.
# +5v is EXP1 pin 10, Gnd is EXP1 pin 9
panel.lcd                                   reprap_discount_glcd     #
panel.spi_channel                           0                 # SPI channel to use  ; GLCD EXP1 Pins 3,5 (MOSI, SCLK)
panel.spi_cs_pin                            0.16              # SPI chip select     ; GLCD EXP1 Pin 4
panel.encoder_a_pin                         3.25!^            # Encoder pin         ; GLCD EXP2 Pin 3
panel.encoder_b_pin                         3.26!^            # Encoder pin         ; GLCD EXP2 Pin 5
panel.click_button_pin                      1.30!^            # Click button        ; GLCD EXP1 Pin 2
panel.buzz_pin                              1.31              # Pin for buzzer      ; GLCD EXP1 Pin 1
panel.back_button_pin                       2.11!^            # Back button         ; GLCD EXP2 Pin 8
panel.encoder_resolution                    4                 # default = 2

panel.menu_offset                            0                 # Some panels will need 1 here
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Probably a silly question :-), but have you tried adjusting the contrast?

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Good one! I bit myself a few times with that and will look for the knob/POT on first power-up from now on.

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I have turnef borg Way
No resultat

This i did not know

I Will look in to it now


Hello I have now looked in my config file and panel is enable. I have also tried to adjust the various parameters in config - udrn luckily. yesterday I had a light on in the background, but strangely it’s not on today. kjeg has tried with 2 different LCD screens, 2 different plug converters and 2 different sets of cables… I have turned the plugs in both directions in all the options I want, there is no longer any light in the screen. What do I do now?

I’m guessing you have not compiled the firmware you are using or you would have known about the config.txt file so maybe you can look for a posted firmware.bin file which someone has which also has the same GUI display and is working. It doesn’t matter if it’s the same machine because at this point you are probably wanting to validate the wiring and screen work. Once you get something up on the display, you now can stop it and go back to your firmware and config.txt file and see what might be different in the config.txt files.

There is a known issue with the contrast on these boards. You can search the web for your board or take a look at this thread and it talks about adding a resistor to fix the contrast issue.