Rear PCB buzzing

[Todd Franklin]

A quick question  regarding the rear PCB..... While plugged in the board buzzes...  I don't recall it doing this before.... if I turn off the house battery at the switch everything is quiet... something I should investigate?  Thanks!

[Fred Brooks]

   Hi Todd,
 There a lot of things that can cause that. We need to be more specific as to what component is making the noise. If you have a stethoscope or long screw driver and can carefully touch the source and hold it up to your ear, Then take a picture with your phone and post it that would give us some direction. It could be the "big boy" charge solenoid or a relay or low 12 volt voltage and so on. Hope this helps, Fred

[Todd Franklin]

https://drive.google.com/file/d/1jbfnQP88YU4ej4-xNDRYrzQS65J5Nvuw/view?usp=sharing

If you click on the link above you will view a quick video I made of turning off the house batteries and turning back on.  Unable to locate buzz by touch but my first suspect is the relay

[Mike Shumack]

I have a relay like that makes the same noise on my Coach (but I don't have that rear circuit board on my '05).
On my Coach, in the front Run Bay, there is a relay for the bay door locks, and that relay buzzes like that every time I turn off the Battery disconnect and turn it back it on.

I have to enter the unlock security code on the keypad at the entry door to stop the buzzing. It seems to be related to the (Essex 1704) "Keyless Entry" system. Once I enter my "unlock code" the buzzing stops and all works as it should. I know it shouldn't do that (buzz) - but I haven't had time to look into the cause. With the front Run Bay door closed I can barely hear it. I think it was buzzing for over a week (after I turned Coach power back on) before I noticed it, and figured out what it was.

I don't know if that board in your video has anything to do with Keyless Entry or not, just mentioning my issue in case it helps you troubleshoot yours.
Good luck

[Stan Simpson]

Sometimes my inverter buzzes when it is charging the batteries after boondocking for a night.