NEXUM is a smart eurorack multi-cable tester.

Plug a cable in one of the sockets and the other end specularly on the opposite side. Check if the blue LEDs light up steady in a number equal to the cores of the cable you are testing. Wiggle the wire back and forth just to be sure that all the individual cores are firmly connected.

Due to its configuration, the connection is considered true only if there is no continuity between the adjacent wires or discontinuity in that specific core. This smart feature will avoid false positives.