Noisy Converter?

[techjak2005]

Finally got to plug my camper into shore power to start to check things out. First thing I noticed is that the converter is very loud. Doesn't sound like a fan noise, more like a transformer noise. BUT when I turn on a 12 V appliance (light) the sound goes away.

The converter is a Magnatek 3220 (20 amp).

I also checked all of the outlets with a circuit tester and they are all wired up properly and have power.

 

[JackandJanet]

Interesting that your converter is 20 Amp. Mine, and I think all the ones found in later HiLos are 45 Amp rated. It's not that you're going to pull 45 Amps through them, because the shore power plug is a 30 Amp one, but it means the converter won't be working as hard if the demands are high.

I don't know what your noise is though. And, it's interesting that turning on something as low Wattage as a light would make it go away. I DO know that transformers can hum however, and that hum will change depending on the output power.

- Jack

 

[techjak2005]

My shore power plug is also 20 Amp (but I think a 10 gauge cable) with a standard plug rather than a 30 A plug. I think they did this (and wired up a pigtail that could plug into the AC input) so that they could run AC with just the one shore power cable - BUT I can't find where that box is wired to, as all other outlets show power (and wired correctly) when I tested them ... unless there's a mystery outlet somewhere!

I had it plugged in for a couple of hours and ran the fridge on 110 (YAY it works!). Then for ha-ha's decided to disconnect and hook up my battery charger. It's charging at 5A, so I suspect that the converter isn't up to snuff, hence the noise.

 

[techjak2005]

So, I've made some more odd discoveries poking around inside the couch (where all the electrical/utilities are installed). There are just 2 breakers, looks to be a main and a secondary. Someone installed a cigarette lighter type outlet and coiled it up near the breaker box, then connected (and electrical taped) a power cord (3 mm connector) to that. Not sure what it was for. The only 12 V item that doesn't seem to work is the bathroom fan. Not sure if I have a blown fuse or the fan doesn't work. I practically have to stand on my head to see the fuses (which are the AGC-type old style glass fuses).
I also found a pair of 12 V wires in the middle of the front wall between the cubbyholes that aren't connected to anything and it doesn't look like there was ever anything wired up to them (or they were cut off and just left in place). I would think that this would be a good spot for a stereo and perhaps that's what they are for?

Someone also set this rig up for cold weather use, as there is a 110 V cord that runs down to the FW tank (I would assume for a tank heater) the cord reaches an outlet installed near the converter. The tank has insulation and lagging covering the tank as well. I just placed an order for LED's to replace the interior and porch lights as well as the stop, tail and turn signal lights.

 

[techjak2005]

Upon further investigation, the shore power breaker is only 15 Amp. The "extra" extension cord they wired up is connected to the "Main" bus-bar in the Load Center which can only accept 4 breakers. BUT the other slot for the breakers is isolated from the main bus. Rather than fiddle with this 36+ year old transformer/converter, I've decided to replace it (as well as re-wire the 120 V system). I opted for a 35 Amp deck mounted converter. I found a breaker that will work with this load center on Amazon that has a 30 A & a 20 A breaker. I will use 10 GA wire to jumper to the second main bus to be able to use the other slots. These will be for the two circuits that are now wired to one 15 A breaker ... Fridge on one and outlets on the other. For now, the 20 Amp breaker will be in case I want to add AC at some point in the future.

I picked up a 12 circuit DC fuse panel that I will re-wire all of the 12 V loads to. There are currently only 4, but I plan on adding an LPG detector, CO detector and smoke alarm as well as adding a fantastic fan in one of the skylights. I will have to trouble-shoot each 12 V circuit to identify what's what since the schematic isn't right for my rig, but I don't think it should be too difficult.

 

[techjak2005]

So, the work continues. Got the parts, but shouldn't have cheaped out on the 12V fuse panel ... the one I bought broke in trying to install it. Waiting for a replacement one. Meanwhile, I have gotten the propane connected up and verified that the stove works ... still need to check the fridge and rest of the propane appliances.

 

[techjak2005]

Progresss!

New fuse block came in today while wiring was in progress! Had to extend a couple lines to reach the fuse panel, but everything appears to be working! YAY!