DECODERS VS OPEN FRAME MOTERS

[CASCENZI]

DO I HAVE TO SWITCH OUT OPEN FRAME MOTERS FOR DCC I SOME SLICK RUNNING PFMS ANDWANT TO KNOW WHAT I'M GETTING INTO WITH DECODER INSTALLATIONS

[Stephen D. Richards]

You don't have to switch motors but just pay closer attention to your wiring that it doesn't get caught up in the motor.   I have set up a couple of Atlas in DCC.  They work pretty good.  I personally like the closed can motors myself, but with limited budget....I'll take what I can get!  Hope that helps some.  Remember, when setting up a loco for DCC, make sure the motor is isolated from the frame.  Stephen

[Jim Banner]

No need to yell with all capitals.  I can hear you just fine.

Whether or not you can use a particular decoder with a particular motor, open frame or can or any other kind, depends on how much current the motor draws when you do the stall current test.  Remember that the stall current test must be done at the correct voltage for your scale.

The only exception to this rule is with coreless motors - the decoder not only needs to be rated for at least as much current as the motor draws on the stall test but also it must be an ultrasonic ("silent") type.

And while you have the meter out, use it to make absolutely sure that the motor brushes are isolated from the pickup wheels.  Many older open frame motors had one brush holder connected directly to the motor frame which then connected to the locomotive frame which in turn connected to the wheels on one side of the locomotive.  This can be difficult to detect without using a meter but the decoder will quickly let you know - with a puff of smoke.

Jim

[richg]

First of all, don't yell. Upper case is yelling on the Internet.

Measure the current draw of the motor with a multimeter. I have an old MDC boxcab with open frame motor that draws about 0.6 amps and an older Digitrax decoder good for 1 amp works just fine. Many decoders handle 1 to maybe 2 amps. Depends on the brand. I run only HO scale.
Many open frame locos have one brush connected to the frame. Disconnect this connection. The motor should only have a orange and grey wire to the brushes.
Sounds like you might be new to DCC. There are many links on the Internet for DCC. Do a Google search for the terms such as, open frame motor dcc.
Good luck on your venture.

Rich

[Doneldon]

CAS-

I'm not yelling, just respecting how you wrote your name.

Keep in mind that it may not be sufficient to remove the original wires to the motor and replace them with the wires from the decoder.  There might still be a connection between the loco frame and the frame of the motor.  This can be fatal -- not to you of course, but to the decoder.  So you'll need to be sure that the motor is electrically isolated from the loco's frame.  This explains the popularity of can motors; they "automatically" make certain that the motor is isolated by virtue of the fact that the can's skin makes no electrical contact with the inards.

Also, don't let this issue deter you from converting to DCC.  It's not really all of that big a deal.

          --D