# Marx Train Transformers



## OldMarxGuy (Jan 22, 2014)

I have been running Marx trains for years, even overhauling and cleaning and adjusting reverse units, switches, and accessories. Apparently Marx and other train transformers output pulsing DC current at up to 15 volts. I have never taken apart a transformer but am curious to know what type of transformer, rheostat and rectifier they contain. To keep working for 60+ years is impressive. Some buzz so loudly that they can get on one's nerves.

PS:I have just read that Marx motors are of open frame AC current design. OK, but how does the E unit work to reverse engine and how do solenoid switches work on AC current???


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## BWA (Jun 16, 2012)

Most O gauge toy trains run on AC.

solenoid coils don't care whether they have AC or DC running through them. They are basically just electro magnets.

O gauge trains also run on DC current, but, you then lose the reverse feature.

The E units are just an electro magnet that pulls on a rotary, or, flip flop type switch to reverse the field windings in relation to the brushes.


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## OldMarxGuy (Jan 22, 2014)

Thanks, I guess that when I push the green button on a 3 wire switch track controller it activates one of the solenoid coils and when I push the red button, it just activates the other coil. Duh!!! Never dawned on me before.


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## BWA (Jun 16, 2012)

Yup, it's as simple as that.


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## jimtone (Nov 11, 2014)

OldMarxGuy said:


> I have been running Marx trains for years, even overhauling and cleaning and adjusting reverse units, switches, and accessories. Apparently Marx and other train transformers output pulsing DC current at up to 15 volts. I have never taken apart a transformer but am curious to know what type of transformer, rheostat and rectifier they contain. To keep working for 60+ years is impressive. Some buzz so loudly that they can get on one's nerves.
> 
> PS:I have just read that Marx motors are of open frame AC current design. OK, but how does the E unit work to reverse engine and how do solenoid switches work on AC current???


I'm asking the same, as my cord is brittle on one #309 25 watt model and I'm not able to find any info about how to change a power cord but only that it needs to be done? Have any of you here seen a documented cord replacement on a Marx transformer?


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## TrainLarry (Jan 15, 2012)

Looking at the photo of the transformer, it looks like the knob needs to be pulled off, and the case needs to be pried up from the bottom, inside the bottom lip.
That should gain you access to the inside, where you can replace the cord.

At 25 watts, the transformer will power up a short train on a small layout.

Larry


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## Taylor622 (Jan 31, 2013)

If the cord is brittle and cracked, it needs to be replaced. The exposed copper wires could touch when it is plugged in and the resulting spark could cause a fire, or at least trip a house circuit breaker. Also, the wire insulation inside the transformer may be brittle and cracked, or the cloth covered wires may not be safe. The cord and wires can be easily replaced if you have some skill at soldering. Do you have a local train club? To have an old yet safe and reliable transformer takes some rebuilding skill.


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## Yukon Jack (Feb 1, 2014)

jimtone said:


> I'm asking the same, as my cord is brittle on one #309 25 watt model and I'm not able to find any info about how to change a power cord but only that it needs to be done? Have any of you here seen a documented cord replacement on a Marx transformer?


I replaced the cord on my Marx 1409 transformer. Took me awhile to figure out how to get the case cover off, but it was pretty much a unsolder the old, and solder on the new, kind of event. The controller did not have to be removed - it came off with the cover.


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## jimtone (Nov 11, 2014)

I took the plung last night and worked the cover off carefully and this being a very basic unit, I blew it out with low pressure air and unsoldered the two wires and resoldered the new doner cable. In was the only wire with any brittle insulation and all inside wires were supple. I reassembled and before cinching the 4 mounting tabs, I checked it to assure all was good and it was. I cinched over the 4 tabs and it is fine! Thanks guys for the heads up. I should have photo documented the the restoration but didn't want to complicate things anymore than I feared they mite be. Would've, should've, could've, I'm new and thought I was in over my head but it was a cake walk! Time well spent.


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## TrainLarry (Jan 15, 2012)

Good job on your repair.
To protect the transformer, put a 2.5 amp fuse in line with the wire that goes to the track center rail.

Larry


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## rkenney (Aug 10, 2013)

jimtone said:


> I'm new and thought I was in over my head but it was a cake walk! Time well spent.


:smilie_daumenpos:

Good job! Always like to hear success stories.

Taking pictures is even more important when you think your in over your head. You can then refer to them as you re-assemble/repair. Forget how something goes, look at the pictures.
:smokin:


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## Kwikster (Feb 22, 2012)

rkenney said:


> :smilie_daumenpos:
> 
> Good job! Always like to hear success stories.
> 
> ...


Not to mention if you get stuck, or want advice those pictures are invaluable to us here. Often our experience can pinpoint a problem from a good picture.

Carl


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## Chinewalker (Jan 29, 2016)

I hope it isn't bad form to dig up a year-old thread like this, but I documented a tune-up on my Marx 1669 transformer, with photos. I had created a PDF of the process for use in the Marx Yahoo group and have attached it here...


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## sjm9911 (Dec 20, 2012)

Not at all, it's good to have the info on one thread so others can see it! Nice job on the tune up.


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