DIY Cable Tester

When I first started working in audio I built a lot of cables. I wanted them to be reliable so I needed a quick and accurate way to verify that my cables worked. I’ve seen some cool testers over the years, but none supported the combination of connectors I commonly used. So I decided to build my own. I purchased parts: plastic enclosure, bread board, five-way switch, four LEDs, four resistors, hardware for a nine volt battery, and a pair of all the connectors desired.

The connectors are, from left to right: quarter inch Tip-Ring-Sleeve, RCA (cinch), BNC, XLR along the top and bantam (TT) along the bottom.

To operate, you simply point the switch at an LED. If that LED lights up, you have circuit continuity. If another one lights up instead, you have a crossed wire. If an additional LED illuminates you have a short. True to my goals the box is quick and accurate.

Curious how the tester is wired? Want to build your own? Here’s a schematic.