Problem with Athearn BB F7's

[Anonymous]

Hope that someone out there has some ideas on my problem.

I am running a DCC layout using an MRC Command 2000 with Digitrax 3.5 amp power supply that allows me to run a non decoder equipped loco. . I have always been able to run 7 or 8 powered locos at one time including those without decoders, up until a few days ago.

The problem I have now is one of my consists is 2 Athearn and 1 Stewart/Kato F7's non-decoder equipped and all are geared almost exactly the same. All of a sudden they have very low speed, and if I try to run another consist of 2 decoder equipped locos, the Command 2000 goes into overload and shuts down in about 30 seconds.

When not using the non-decoder equipped consist I can run 8 decoder equipped locos (5 Athearn F7's) without any problem for hours on end. The ones giving me the problems have been cleaned and lubed, and all electrical connections are hard-wired for reliability (ready for decoders when I can afford another batch). But I am stumped on what is going on all of a sudden.

[rrinker]

Perhaps a dirty commutator or a shorted motor winding - one of the motors may have overheated and burned one of the windings, allowing it to short out. DO you have a meter that can read DC Amps? Try testing each of the three problem locos with a regular power pack and you meter, and check the crrent draw of each one. I'll bet one is abnormally high.

--Randy

[Anonymous]

Also, do any of these locos have metal couplers. The coupler can cause a short because the frame is used to conduct electricity to one side of the motor. Just a thought.

[rrinker]

Yup, putting regular Kadee couplers on most Athearns is a recipe for problems, since the frame is grounded to one rail. The coupler fastening is not completely rigid, so the sorts caused b this aren't continuous, and will allow the locos to move, sort of. Easy to test, take the two units causing problems, and flip one around front to back, if the problem goes away - it's the couplers. There's an exact alternate to the #5 with one difference, the shank is plastic, which is the preferred option for Athearn BB locos. That one is the #28.

--Randy

[bogp40]

As tweet469 has mentioned, that is a possibility of the coupler problem. Uncouple the consist and run them. If the couplers are the trouble, replace them w/ the Kadee #38- these are Delrin shanks and as durable as any #5. If you want closer coupling(radius permitting) try using the #33 short centerset on the rear of the "Fs". If the couplers are not the fault, the continuous running of multiple units in analog may be doing something to the command station. Others more informed w/ DDC may be able to help.
Bob K.