Keeping your world up and running.®

Tracing an intermittent with a 179 DMM

By Bryan Shaw

April 2007

I needed to solve an intermittent problem in a radio broadcast studio: On occasion, all of the audio would drop out for a second or two. None of the likely causes checked out, and it took weeks to correlate the problem with the exact cause - one of the microphone channels on the main console. I was able to look for the cause of the problem by comparing the faulty circuit board with two known-good circuit boards, using my Fluke 179 DMM. I eventually found that one potentiometer was set incorrectly; it was turned 180 degrees in the wrong direction, sending the wrong voltage to an amplifier.