The Roster

Sunday, February 28, 2016

DC in an AC world...

Back in January, I purchased an American Models SD-60 locomotive from a vendor at the World's Greatest Hobby On Tour show. It was the CSX road name which is increasingly difficult to find. I took the train out of the box this weekend at the Muncie and Western train show for it's inaugural run.

The end of the box. Some wag has marked the unit as "AC". It's a high rail model, and the DC box is bot checked.

It would not work.

It just sat there and vibrated. A couple of folks looked at it. One theory is that it was a DC model (everything I have is AC).  So I set it aside and got on with the show.

Today, I had a chance to look at it. Rich B. lent me a DC rectifier that I could hook up to my AC transformers. First up, I removed the body to inspect the chassis, the motor and the gearing assemblies.

I went to disconnect the headlight and the whole circuit board came loose! Talk about a tight connection!

I also pulled the body off another SD-60 in the collection for comparison.

The CSX engine and circuit board

The AC High rail circuit board. 

As the pictures show, the two circuit boards are clearly different. I placed the chassis on the track  and hooked up the rectifier. A little bit of movement! It would move and bit then halt.I'd throw the switch and it would go the other direction.

While I had it open, I checked the rotation of the motor shaft. It was experiencing some binding, but there was nothing obviously wrong. From past experience, I know that if you overtighten the plates that secure the drive shaft mounts for the large flywheel, the shaft can bind, so I backed off the screws until the two plates were snug but not tight.

I tried it again. Success! The engine would move back and forth. But only at very low power levels. If I raise the power of the AC transformer, the engine would slow and then stop. But at low speed, the engine moved and pulled the large intermodal freight string around the layout.

The CSX engine moving freight on it's demo run.

Verdict: This is a DC powered engine.

Well...poop. All my other engines are AC. So guess, I've got a DC engine in the collection. 

In other news, added a new box car to the collection. A nice Showcase line car for the DT&I.

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