Humming sound out of my RV’s sound system

[cantdrv55]

I’m trying to track down the cause and thought you guys might be able to help me narrow it down.

The system consists of Sony PS which we use as a gaming system and DVD player. There is also a Samsung TV and a RV type head unit that plays CDs. All are connected through an inverter buried deep in the cabinet. When I’m plugged into a wall outlet, everything is powered by 120 VAC. The same through the inverter which gets 12 VDC from the RV battery. Don’t think anything is powered by 12 VDC directly but I have not yet taken the cabinet apart to confirm.

My question is, what typically causes the humming I hear through the RV speakers? Bad ground? Poor quality inverter? Crappy head unit? I’m leaning towards the inverter but unsure. What troubleshooting steps should I take other than unplug one source from the inverter one at a time?

[Sooner or later]

Check the grounds. Try to use one place for all grounds.

[onewhippedpuppy]

When I’ve had that issue in vehicle audio installs it has been a poor or loose ground connection. I would gain access to the wiring and inverter, do a physical check of the wiring, and then start disconnecting components to narrow it down. Note that it could also be a loose connection at the speaker, so don’t forget that side of things. An internal issue in one of the components could also to blame. Does the hum change when you switch audio sources?

[cantdrv55]

The hum is constant regardless of input source selected. As far as poor ground is concerned, I’m going to have to take more than the cabinet apart to track down, something I’m not looking forward to doing but necessary it appears.

[asphaltgambler]

Does it happen with engine running or off?

[flipper35]

Sounds like an AC hum in the amp. Usually a bad or no ground is the cause on that.

[cabmandone]

Does the sound change with the rpm of the vehicle?

[cantdrv55]

The sound is there whether the motor is on or not but don’t think it gets louder when revving. I’ll have to check that out.

[cabmandone]

If it's there motor on or off might be a bad inverter or just a bad inverter ground. Ground is cheap, if not easy place to start. Proper size of ground wire makes a difference too.

Side note: I'm not familiar with RV head units but if the noise is coming through the stereo system, I'd start with where it gets ground. Could also have a power and audio wire run too close together and you're picking up a hum. But normally that one will vary with the rpm.

[cantdrv55]

Thanks guys. I’m digging into this on the weekend.

[tevake]

My tunes in the coach would go hummm if the sink Florissant light is on in the gally, Turn that off and it's good.

I haven't taken the coach anywhere for a while and think the stereo in the dash may have stopped working. Got to check that out

Cheers Richard