GLCD Not Workiing

Machine: K40 with m2NANO board

Board: Cohesion3D LaserBoard

Firmware: Smoothie

Problem/ Question: Everything works except the GLCD. I have checked the wiring (just 2 ribbon cables) at least 5 times and have had a second set of eyes verify the cable installation and orientation. The machine works perfectly with or without the GLCD. What am I missing?

Thanks for your assistance in this matter.

Please show some pictures of the C3D board, screen, and how you have it all wired up.

I apologize, I thought that I had attached pictures.

Hi Pat,

We have better instructions for installing the GLCD in the install guide for our previous board:

https://cohesion3d.freshdesk.com/support/solutions/articles/5000726542-k40-upgrade-with-cohesion3d-mini-instructions-

Can you please review those to make sure that you have the ribbon cables going to the correct spots? The zip tie or other labeling trick definitely helps to make sure that the correct cables are in the correct spots.

Those are the instructions that I have been following. Attached are 4 more pics. Note that the ribbon cable between the EXP1 connectors on the GLCS and adapter has been marked with black tape at both ends.

They look like very long cables for a GLCD, and I know they can be very susceptible to cross-talk - do you have any shorter cables you could try just to rule that out?

Also, some versions of the GLCD have the connectors on the wrong way round. Can you try to reverse the cables on the LCD end - flip the cables round by 180degrees (you’ll need to cut the tab off the cable connector to be able to do this)

Andy, thanks for the input. I have checked the cable and pinout orientation and everything is cabled per Cohesion3D documentation. In addition I have checked end-to-end continuity on both ribbon cables. The ribbon cables that are being used came with the GLCD and supplied by Cohesion3D. I am apprehensive about flipping cable connectors or modifying connector keys when everything is in agreement with the vendor’s instructions. Possibly if the vendor were to provide guidance in this direction, I would attempt the realignment of the cables, but until then I believe that I may have a defective GLCD board or some option missing in the config file or on the LaserBoard.

This should not be the case on the screens that we sell and I think his pictures look correct.

Pat, what are the exact symptoms? Are you getting a blue backlight on the screen when you power up?

There appears to be no response on the GLCD.

There is no blue backlight. I have rotated the small potentiometer (bottom left on the board) both fully clockwise and counter-clockwise with no results.

I do not hear any high pitched sounds from the GLCD.

As stated earlier, I have double checked the cabling (see previous notes). I have run continuity checks on the cables. I have not taken voltage measurements from the LaserBoard to the connectors that plug into the GLCD.

All the functions of the LaserBoard work as expected while running LightBurn whether the GLCD is plugged in or not.

Anything else?

This is strange, I have not seen this particular thing happen before before.

Please use the Contact Us form on the website to reach out with your order number and reference to this thread so that we can provide a resolution.

Did you try turning the little grey brightness knob?

Yes, I have. But, alas, to no avail. Based on a prior note from C3D, even they are stumped. I am will be looking into GLCD via Amazon for one third the price from C3D. If the new one works, then the old GLCD assembly is broken. If not, then I would suspect something on the LaserBoard. Still working through it.

My vote is for the 3M ribbon cables. I’ve had bad luck with them over the years since first saw them in the 1970’s.