60 cycle hum?

[John]

There's a noticeable hum - sounds like a typical 60-cycle noise - in the speakers of the 110V stereo system onboard whenever I'm not using shore power. It also shows up when I transmit using the VHF away from the dock. I haven't looked at the overall AC and DC system configurations yet but I believe that they are pretty standard. Any ideas as to cause?

 

[Phil Teter]

Grounding

Check your onboard AC grounding.

 

[Ken Palmer]

What can it be?

John, it sounds like you have something else running on that fancy big boat <g>. Most likely an AC inverter running from your battery. You may also have fluorescent lighting that can cause hum. You need to check by elimination. Turn off everything except for the stereo and listen for the hum. If it's gone, turn on one breaker at a time until the hum returns.Since your stereo and VHF run off off 12VDC, there is no AC on the power line unless its coming from something else.Good luck,Ken Palmer, S/V Liberty

 

[R.W. Landau]

Inverter

John,This sounds to me like a square wave inverter. Stereos don't do so well with them.r.w.landau