An Idiot DC electrical question...

[alton6]

The other night I dug a Lionel Fundimensions 8903 Rio Grande steamer out of the miscellany pile, and while wondering where I had aquired it from, attempted to fire it up on the layout. Oh, oh........no go!

Did I fry the motor in this puppy with AC current, or not? Is it fixable? I know the 8903 is (was) a pretty basic o-27 engine. What was the set it came from, and what year(s)?

Any other Lionel MPC DC runners out there that people should be aware of?

Thanks,

Carl

[wrmcclellan]

You are probably OK if you did not smoke the motor. As long as the windings are intact there should be no problem.

Regards,
Roy

[ben10ben]

A small amount of AC current, as in for just a few seconds, shouldn't harm it any.

[thor CNJ]

I have a little Sanbta Fe docksider MPC that's DC. I almost fried it running AC, but realized that for a while Lionel did what Marx had done: make a few very cheap DC sets on the side. No problem. I think the Docksider will be doing show duty next year.

[Big_Boy_4005]

Those DC motors usually do a twitchy little dance on AC. So, like the others said, if you didn't leave it on too long it should be OK.

Lionel's DC only sets were short lived, only a couple of years in the early 80's, and only on the low end traditional stuff. 8903 would be an odd number to be DC, because the 9 suggests that it was made in 1979, too early for DC only. It is possible that that engine was made both ways if the set was carried over into the early 80's.

[alton6]

Thanks, guys. Probably need a DC transformer to see if it really runs. How were DC transformers wired to the 3-rail track?

Were there any DC diesel engines produced in this period? How about postwar 0-27 products?

Are DC motors cheaper or simpler to make than AC?

[Anonymous]

Very cheap. Most of the dc motors used today are by mabuchi and I can pick them up at our local axman for a buck or so.
As far as a dc transformer just go to radio shack and ask for a 10 or more amp bridge rectifier and connect the two ac leads to the two posts with wavy lines on and then the plus and minus to the track.
To reverse you need a double pole double throw switch which will change the polarity to the rails. Dave.

[daan]

Those can motors can handle small amounts of ac without big problems. If it's fried, you can change it easily in low price.
I guess the option with the rectifier is the best solution I think.

[brianel027]

Actually the DC powered sets were started by Lionel as early as 1976 with the Yard Boss set that came with the Chessie Industrial Switcher and remained in production as late as 1990 with the Freight Flyer Set which came with the #8902 ACL 2-4-0 steamer. Also the Badlands and the Cannonball Express set, which also featured the primitive MPC invented mechanical Sound of Steam in the tender (though young kids do like it).

I'm very fond of the DC powered locos, even the cheap ones. They're great projects for improvements and because of the lack of the circuit board, there's more room to add weight to the loco. I have a re-done #8902 in 2-tone Lehigh Valley pulling a dozen cars no problem.

I'm sure the DC sets offered by Lionel for this 14-year period were obviously a cost cutting / price control move. The only real drawback to them (outside of not be able to use track power whistle / horn nor Railsounds) is the cheap DC power pack that came with them. It's wasn't very sensitive and delievers too much voltage to the track at its lowest setting. That and there was no amperage reserve, so only a couple of cars with lights could be run. The new DC power pack that currently comes with the Bachmann HO sets is such an improvement and runs these Lionel DC sets very very nicely.

You can also wire in a full wave bridge rectifier to a Lionel AC transformer along with a throw switch to change polarity of power to run DC power to the track. Lionel also at one time made a DC converter box for its G scale line that works with AC transformers. Outiside of having to clean the track and locomotive wheels more frequently, I find the DC current does run these lower-end locomotives much more smoothly and consistantly even on tight 027 curves. I think of it as poor man's speed control.

I know I'm the odd man out here, but I usually am.[8]

[Anonymous]

Not to be critical but a novice may think that a full wave bridge rectifier and a bridge rectifer are different. As far as I know they are the same. And if you really want close to pure dc get a 35 volt 2000 mfd polarized electrolitic capacitor and wire - to -DC and + to +dc. I will filter out any ripple unless you load it faster than it can charge, but for trains it is not necessary.
I do have a American Flyer 332DC that I use a 30B transformer with a rectifier on and it is not an extremely fast locomotive. I found a 5000 mfd cap that I ran across the bridge and it increased the voltage by 5 volts as it is able to load up faster than the train takes out. Really makes it smoke great too and no problems.
Dave.

[ben10ben]

If you want to modifty the engine to run along with your other trains on AC, it can be done for under $20($17, if I recall correctly) and a few minutes of work. It involves installing a Lionel electronic e-unit in the engine between the track and motor. There's an article that tells you how to do it on the Lionel website.

[daan]

Good remark ben10ben, it will make DC and switch direction. The one with the capicitor to filter out any rimples from converting AC to DC can only be done if you're satisfied with one direction. If you would change direction the capicitor will be charged from the wrong side and blow up.

[brianel027]

If anyone needs a basic model circuit board for this, email me and let me know. I have loads of them I could sell.

[lionelsoni]

Daan, you just put the capacitor upstream of the e-unit or whatever switch you use to change direction.

[krapug1]

My New Englander Freight Set from '81 (written about in the Jan CTT), came with a transformer with AC posts on one side and DC posts on the other, with "train" engraved below the DC posts. The number on the transformer is 4060, and this does a great job of running the DC steamer (8007) that came with this set. Normally these type of transformers are dirt cheap on E-Bay.

[lionelsoni]

A bridge rectifier is a full-wave rectifier; however, a full-wave rectifier is not necessarily a bridge rectifier. "Full-wave" means that both half-cycles of the AC waveform appear, with the same rather than alternating polarity, in the DC output.

One way to do this is with a bridge rectifier. The disadvantages of a bridge are that it uses 4 diodes, that there are always two diodes and therefore two forward-voltage drops between the input and the output, and that there is no common point between the input and the output terminals. The considerable advantage is that the input can be a single two-wire transformer secondary winding.

The other common full-wave rectifier uses a center-tapped transformer secondary winding, with the center tap common to the input and output circuits and a single diode in series with each end of the winding.