Replacing 1977 converter and low voltage distribution panel

[DWG-77]

Hi there I was hoping to get some recommendations on choosing a new converter for my 1977 Airstream.

We have a 21 foot Land Yacht with a 30a electrical system and are planning on using the trailer essentially always with access to shore power.

The original converter is a 40a Magnetek model 3240

I was planning on replacing both the converter and the old low voltage distribution panel.

My understanding is that is possible to get converters that have a built in low voltage distribution panel.

I have been looking at Progressive Dynamics converters but I am having difficulty finding a model that has the built in low voltage distribution panel.

I would greatly appreciate it if anyone can tell me the specific model number of a Progressive Dynamics (or other brand) converter with the built in distribution panel.

[Bill M.]

Me, I do not see the point in replacing the distribution panel. I have replaced the power converter in my 2 trailers and left the old distribution box. I use the trailers a combined 8 months a year and I have had 1 blown fuse in 12 years. A shorted 12 volt outlet that fried with my CPAP. I found a replacement fuse.
So my recommendation is to replace the PC with the Progressive Dynamics you are looking at and leave the panel. That makes it pretty much a change 2 wires job. On mine I drilled the rivets in the case of the old PC and clipped the wires inside at the terminals. That left enough wire to just attach them too the new converter,

[DWG-77]

Yes the more I think about it the more I agree with the approach of replacing the converter only. My main reason for replacing the distribution panel was to move it under the bed so that I wouldn't have to get a cut out of the mattress.

One final question. Our trailer has a 30a AC electrical system and the original converter is 40a. I am planning on using a single battery as we will only be using it with access to shore power. I am trying to decide whether to buy a 30a or 45a converter. The 45a is obviously a little bit more expensive but forgive me if this is a stupid question but I don't understand what the advantage of a 45a converter if I am going to have a 30a power source.

[Bill M.]

DC power is violets x amps. The 30 amp outlet on the campground pedestal is 30 amps at 120 volts. The converter output is 35 or 45 amps at 12 volts. The converter converts the 120 AC input into the 12 volt DC output. So it only takes 3 or 4 amps of the AC input to produce 30 or 40 amps of 12 volt output. Get either of the converters you mentioned. I would probably get the larger one for stationary use. I do not see a downside to it. Or a need for it. In your case you will never discharge the battery so you do not need to recharge it fast.

[DWG-77]

Thanks for the help understanding the system.

[richard5933]

With only one battery and always being on shore power, the smaller converter will likely be more than enough if you need to save a few bucks.

[steve46]

I redid all systems in my rebuild of our ‘76 Trade Wind and used a Progressive Dynamics PD4060K unit. It works well and serves my needs. Here are a couple of photos.

[AldeanFan]

On my ‘77 Safari I replace the converter with a powermax PM4-45AMP based on forum recommendations. That was in 2016 and it has been flawless.

I also replaced the glass fuse panel with an automotive style fuse panel I bought at an autoparts store. Some of the fuses had overheated the metal clips and they didn’t contact properly anymore.
As an added benefit the trailer now uses the same type of fuses as my truck.

[mousouchop]

Originally Posted by steve46

I redid all systems in my rebuild of our ‘76 Trade Wind and used a Progressive Dynamics PD4060K unit. It works well and serves my needs. Here are a couple of photos.

This looks great! I am redoing systems in a 75 Tradewind (that is otherwise staying stock). Were there any “gotchas” in this conversion? I expect every wire from the old blue tube fuse panel has a home on this new converter/control panel?

[steve46]

It has been so long since I tore out the old 12 volt and 120 “boxes” that I don’t recall what they looked like or the color. I will say that the new PD unit accommodated all of the old circuits, both AC and DC, and allowed adding additional circuits.

[mousouchop]

Originally Posted by steve46

It has been so long since I tore out the old 12 volt and 120 “boxes” that I don’t recall what they looked like or the color. I will say that the new PD unit accommodated all of the old circuits, both AC and DC, and allowed adding additional circuits.

This is great news. I am agreeing, that it seems the new PD/Converter combo should accommodate everything. I have two questions that maybe you can answer, though you may have forgotten these details...

1) Did you find a place to hookup the Ammeter plugs (rubber elbow connectors on red and black wires)
2) Did you retain functionality of the original "Central Control Panel" in the kitchen cabinet? This usually relies on a wire from the fuse (12v distribution panel) to the converter. Since it is all one unit, I am hoping this "connection" exists already.

I think a "workaround" to question 1 above may be to hook up the old 12v distribution panel (blue metal glass tube fuse box) as member on the 12v blade fuse panel, and allow the ammeter/control center to still feed off of that prior setup.

Thanks again!

[steve46]

The Central Control panel required significant “monkeying around” but I do have much of the functionality. I must say that the reinstallation of this was very challenging and I had Woodland Airstream (they are very experienced in vintage Airstreams and do extensive restorations) do the actual reinstall. I cleaned things up a lot and made it more presentable, but it is not perfect.

Here is what works:
—exhaust fan
—power on light indicator
—water pump switch
—panel lights
—battery check: it registers and I’d guess it is reasonably accurate

Here is what does not work/register:
—ammeter
—tank levels, all three—at the time this was not important to me so I did not test or run new wires as I did not replace any of the forty year old sensors.

Here is a photo of the reinstalled Central Control:

I hope this helps.

[mousouchop]

Originally Posted by steve46

The Central Control panel required significant “monkeying around” but I do have much of the functionality. I must say that the reinstallation of this was very challenging and I had Woodland Airstream (they are very experienced in vintage Airstreams and do extensive restorations) do the actual reinstall. I cleaned things up a lot and made it more presentable, but it is not perfect.

…

I hope this helps.

This is good to know! I ultimately think that I will get new monitoring systems, and consolidate that nonsense all to one closet. I’d love to get a whole kitchen cabinet back…

Anyway— I am looking to do this install this coming week, and just have another question or two you might have an answer for…

RE: the 12V breakout on the PD unit… it has positive leads coming out of the back, numbered to match the blade fuses on the front. I surmise that I will marry these with the purple/pink/yellow/brown lines coming out of the old tube fuse box. The question is, install videos show people taking the 12V negative lines and installing on a negative bus bar and grounding that to the chassis… but, I don’t see the current negative/ground leads for the 12V wiring on or near the stock DC panel. So, I expect that the lines are “properly grounded” in another location, and I need only worry about moving over the colored positives to the new box? This is supported by the fact that stock light fixtures only have one wire (positive) leading to them, no negative. If I install something new like a Maxxair fan or modern LED that has a negative lead, my understanding is that can just be grounded to the frame/chassis locally at the fixture install site; i.e. I need not run a negative line all the way back to a neg bus bar in the closet. Does that sound right?

Lastly, the PD unit doesn’t seem to have a Car Battery in feed like the old 12V tube panel has. I assume this just means that the PD unit doesn’t allow for battery charging via the tow vehicle when in transit. I assume I simply cap and tape the blue car battery positive line for now (which I believe comes from the 7-pin towing cord).

Thanks for any clarity you may be able to provide.

[steve46]

All of my 12 volt “appliances” have a colored wire, the color depending on the circuit, and a white ground wire running to the fixture/appliance. I believe that all of the white ground wires run from the “buss bar”, mounted low on an aluminum rib, behind and near the power center.
The Progressive Dynamics technical phone support staff are very helpful if you need additional information. Best of luck with your project.