DCC, Decoders and Open Frame Motors...

[Anonymous]

I just bought an old PFM AT&SF 4-8-4 with the old open frame motor. I am planning on having my layout run on DCC, but I'm confused about this old motor. Can it be used on DCC at all? How big of a job is it to remotor? Is it worth it to remotor? Does it affect the value of the engine, either for better or worse?

Thanks guys.

[cacole]

The only thing you will need to do to use the older motor on DCC is to isolate it from the frame, if the motor still runs. Try it on DC first, and make sure the motor is still in operating condition. In order to isolate it from the frame, you will need to place insulated electrical tape between the motor's frame and the locomotive's frame, and replace the metal screw that holds the motor in place with a nylon screw. An alternative would be to thoroughly clean the motor and frame with rubbing alcohol and stick the motor in place with double-sided white foam tape; however, most of those old motors were not perfectly flat on the bottom and this may not work. Either way, check the motor with a meter set for Ohms or a continuity check tone, and insure that the motor and frame are not touching. The wires to the motor will need to be unsoldered for this test. A decoder with wires instead of an NMRA plug can then be installed and should work just fine, as long as you get a decoder rated for at least 1 Amp. The Train Control Systems T-1 or a Digitrax decoder would be a good choice.

[cjcrescent]

Two things should also be determined about that old motor. One what the stall current is, that is how many amps does it draw when the physical load on it prevents it from turning. Being a steamer this should be determined by removing the boiler and applying pressure directly to the motor shaft and never by pressing down on the mechanism while its on the tracks. This can damage the mechanism.
Two, and this is one that not many people have tested for, but with DCC it can make a BIG difference, and that is what is the breakaway amperage. That is what is the amperage the motor draws until it starts turning under a load. Many times this amperage is as great if not greater than the stall amperage. If this exceeds the peak rating of the decoder other than a moment or two, it will fry it. I fried a 1.5 amp decoder in a loco than the stall amps were only 1.2, but the breakaway amperage was almost 1.75. The motor was replaced and I haven't had any problems since.

[JerryZeman]

QUOTE: Originally posted by wes454

I just bought an old PFM AT&SF 4-8-4 with the old open frame motor. I am planning on having my layout run on DCC, but I'm confused about this old motor. Can it be used on DCC at all? How big of a job is it to remotor? Is it worth it to remotor? Does it affect the value of the engine, either for better or worse?

Thanks guys.

I have several old PFM - Tenshodo locomotives equipped with decoders, with original motors. I've been using NCE the older D102 decoders, which I believe has been superceded with D13SR. These are 2 amp peak decoders, 1.3 amp continuous. None have failed in service. One of my locs, a Great Northern M-2, pulls well over 1/2 amp, actually, closer to 3/4. Same with a friends United H-6s, and we have run the heck out of them since I put decoders in them, no problems.

I remotored two of my Tenshodos with Can motors (I think they were A-Line), as the magnets were too weak, and one had excessive noise. Not hard to do, I set in my motors with black RTV as opposed to making up brackets. The RTV quiets down the installation also.

My advise would be to use the original motor unless you have problems with it. If you prefer other brands to NCE, go for it, as long as you stay with ratings that can handle the higher currents of the open frame motors.

regards,
Jerry Zeman

[Anonymous]

thanks guys. your advice is greatly appriciated!! I haven't had a chance to get her on a test track yet, so I don't know how she'll do stock. I'll post what I find out over the weekend!

[mcouvillion]

wes454,

I've posted other threads recently about working over older motors to get them to run well. You might backtrack a little and find them. Essentially, if you clean the commutator, remove the end-play, and lightly lubricate it, it should run as well as it possibly can. You might be surprised! Like some of the others, I too prefer to use the original motor, as it is what the engine was designed for and remotoring can be a pain.

I had not heard about the "breakaway current" and am still curious how to measure it. cjcresent, can you give us an idea how it is measured, with either an analog or digital meter. I know the older motors draw a little more current, but some are just fine once cleaned up. (I do have a couple of old Athearn motors that draw 2+ amps! They are in a box and probably won't ever be used.)

Mark C.