I’ve checked the pins of the cable on the Cintiq 21UX and they seem fine.

Any ideas?

I know it’s old, but I’d love to get it working it again if at all possible.

I know it’s not a driver issue as it happens with what ever I plug into it.

Model: Cintiq 21UX
Cables used: The DVI in cable that is built into the tablet. 
I have tried plugging in an old MacBook Pro that has DVI out directly into the tablet. 
I have also tried plugging in a Nintendo Switch using a HDMI to DVI adaptor.

⟐ Answer accepted December 29, 2022 at 4:39 MST

The display has a built-in DVI-I cable.

The following inputs will display a picture on the device

• DVI-I direct input
• DVI-I to VGA (using the supplied VGA to DVI-I adapter [88741-9100, Molex])

The following will no longer display a picture on the device. But they were working until recently:

• DVI-I to HDMI (using a 3rd party adapter)
• DV-I to Thunderbolt (using Apple thunderbolt adapter).

Does anyone know why these adapters would suddenly stop working? I have tried them on other displays, and they work perfectly, so I know the adapter is not a problem.

The unit comes with DVI-D to DVI-I adapter (88741-9400, Molex) but it makes no difference if this is used or not with the adapters that no longer work.

Here is a picture of what the pins look like on the built-in DVI-I cable:

It doesn't look like any of the pins are bent.

I seen a video for another Wacom screen where they opened the unit and cleaned the ribbon connectors to the screen and it cleared the problem. is there a fix or should I get used to the spot