Universal Robots UR5 Service Manual page 23

Power cable
An adaptor plug is needed for the 48V power. There are two versions.
One plug is for CB2->CB3 and one for CB3->CB2.
CB2 to CB3 looks like below CB3 to CB2 looks like below
Important when replacing a size 1 joint: The connectors need to lay flat, on the connectors' lowest side,
when mounting the blue lid. If not, it can cause issues when mounting the lid but also effect the sensor in
the size 1 joint as the plug is pushing onto the setup.