Loud hum when electric hooked up
 

Just bought a 1995 18' Towlite. We have it set up at home now to renovate it. However, when I plug in the 120v I hear a loud hum coming from the converter box. When we inspected it pre-buy, he had the electric hooked up and it worked fine w/out a hum so either the converter suddenly went bad or something else is wrong.

Originally we had a 25' 12/3 extension cord to hook up to the nearest outlet but it was suggested that the 12 gauge wire may be too thin and is causing the hum. So I upgraded to a 10/3 but am still getting the hum. The wire running to the outlet may be 12 gauge. Basically I want to make sure I'm chasing the correct rabbit hole......so what power is needed to run to the camper? Is there anything else I should be looking at?

The hum is probably coming from the transformer in the converter. It is a normal noise put out by the plates vibrating from the alternating current. The material that holds the plates together may have dried out over time. I don't know if there is a good way to quiet it down. They used to be held together with bolts but now they are glued. Replacing the converter is probably your best solution and it isn't a difficult job. There are a couple of options for doing that. Unless you are using the A/C or a microwave when plugged in you only need a normal extension cord and a 15 amp outlet. If you use the A/C you will need a 30 amp outlet and the heavy duty cord.

HiLo problems
 

On my HiLo there is also a cooling fan in the converter that you can hear when it comes on. It comes on when the converter gets hot and shuts off when it cools down. The next time you get the hum, shut off all the circuit breakers one at a time and see if the hum goes away. There could be something on one of the AC circuits loading down the converter. Let us know what you find out.

Jim L, don't you think the fan would come on when there is a load on DC rather than AC, such as the fridge in DC mode or when the battery is in bad need of a charge.

HiLo problems
 

Rich; Since the main job of the converter is to change AC to DC I agree with you that the most heat is generated when a heavy load is on the DC side. He might try pulling the fuses one at a time to see if there is a heavy load on one of those circuits. He also should have the battery checked to see if that is the cause due to it being defective.

Anything is possible. I have seen where a lot of people have had the transformer hum and it didn't seem to be much to do with the amount of load placed on it as I recall. I have never seen any recommended ways to silence it. It should be a simple fix outside of replacement. Finding a replacement may be difficult. You could inquire here to see if they can help you:BestConverter - Converters, Inverters, Electrical Supplies, Electronics

Purchased our converter from Best Converter.
 

Have the old model # so they can advise you. Fast shipping and great tech support.

I had a hum in my 99 towlite and charged my half dead battery and it went away. wound up replacing the battery b/c it wouldn't hold a charge

The noise indicates an ungrounded system
 

Make sure the three prongs on electical plug are properly connected. check inverter terminals for build up of carbon ( darkened) clean with pencil eraser. or sand. check ALL GROUND WIRES SUPPLYING INVERTER