Fluctuating 120vac in TT

Thanks for the update!

Well I crawled around and cleaned up all the ground connections at the frame and checked all other grounds for tightness with the same results. I then replaced the converter with a new NON- WFCO and all problems have gone away. Everything is working normal. Thanks to everyone for their help and advice. Hopefully I have learned enough to help the next guy.

If both your batteries are holding a voltage of 12.6 V and, with the converter powered, if you are still experiencing voltage fluctuations, then the converter has failed. I would suggest to replace with another brand than WFCO. There are many unhappy users of that brand on this Forum.

It does sound like(pun intended) the converter/charger is bad since the problem goes away when you disconnect the shore power and the charger becomes inactive. At least make sure all the connections(especially the connections to the frame) near the batteries are corrosion free. I use an anti-oxidation grease for any connection that is outside. Corroded connections can cause the charger to work harder than necessary and introduce interference into your audio system.

Replaced battery number two and the problem is still there.Is it now safe to assume that the converter is bad?

Here is a 12v battery voltage State of Charge chart:
12.6+ = 100%
12.5 = 90%
12.42 = 80%
12.32 = 70%
12.20 = 60%
12.06 = 50%
11.9 = 40%
11.75 = 30%
11.58 = 20%
11.31 = 10%
10.5 = 0%
Battery number 2 is bad. Your converter cannot charge a bad battery and is overloaded.

The buzzing in your speakers may be caused by LED lights or the overloaded converter.

But the speaker buzz was present while batteries were disconnected. Is it related or just another problem?

Battery 2 is bad according to your readings.

Newman, here is what I did. Yesterday unplugged ac from TT. Today both batts were good. Disconnected both batteries and reconnected ac. Tested from converter 13.67v steady. Tested unconnected battery 1 tested 12.74v and battery 2 10.65v. While batteries were disconnected no fluctuation in lights or outlets but got speaker buzz with stereo off. Reconnected batteries & ac and turned on lights and nothing went wrong. Started heater and all problems returned, fluctuations in lights and ac outlets. Turned everything off and converter was clicking. Found converter, it is a WFCO WF-8845.

Should try disconnecting one of the batteries if you have dual 12 volters. See if lights fluctuates. Then disconnect that battery and see what happens with the other.
If you have two batteries, only one bad cell could cause the fluctuating.