Consisting Problem

[nodcc4me]

I have two identical Life-Like PA-1's. They both run well by themselves but when consisted, one of them will constantly post a "Motor over current" error as soon as the throttle is raised. If I break the link and reset the LM-2s it will run just fine again. The full current setting is almost the same on both locomotives. Any ideas on what to look for?

[KB02]

I'll admit, I don't even own a Railpro system yet, I'm just gathering information at this point, but the first questions that popped into my head is: Are both locos are set to run in the correct direction?

[G8B4Life]

The usual suspects: Both LM's up to date?, the HC up to date?

Apart from those I'd check that they both set off at roughly the same time, ie one isn't trying to push the other (staying at standstill) and stalling out. I would think the pushing one in that case should spin it's wheels before it got to overload so take that theory with  grain of salt. You can try raising the overload current setting and see if that helps.

- Tim

[Alan]

Is either locomotive by itself real close to the maximum LM current to begin with?

[nodcc4me]

Neither locomotive reaches more than 50% of maximum current when operating independently. If I uncouple them but keep them linked they run fine together. Everything is up to date. I'm inclined to agree that one is putting a strain on the other, but there is no evidence of that until the overload occurs. I put a string of cars on the problem child to add a mild strain on it and it ran very well.

[Alan]

What happens if you physically turn one loco around the opposite direction and then couple together?

[nodcc4me]

I linked them both in the forward direction and they ran without error. What does that mean?

[Alan]

Your motor leads are not electrically isolated from the loco frames.

[nodcc4me]

OK, I still don't fully understand why that changes things when they are unlinked. Are they shorting out through the couplers? If I reverse the motor leads on the problem loco will that fix the problem? This was never an issue until recently.

[Alan]

Presumably yes, the electrical path must be through the couplers. It is the only place the two locos physically contact each other.

The clue was your comment "as soon as the throttle is raised". At 1% throttle no motor should exceed LM limit.

Reversing motor leads is not a solution. That would make the loco directional dependent forever. Not good.

Place an ohm meter across a motor lead and frame. Repeat for other motor lead. If either shows continuity then you have no choice but to electrically isolate the frame. Frames in the electrical path are never good. Other issues will arise down the line.

I suppose you could use plastic whisker couplers but that is a band aid fix at best.

[Alan]

Quick and dirty test:

Do you have any old style glass tube fuses? Something in the less than 1 amp range. Lower rating the better.

Position the two locos with the fuse ends in the couplers. Press them together tightly so the fuse makes good contact. Hit the throttle. Does the fuse blow?

[nodcc4me]

I'll try the fuse later and report back. I appreciate the help.

[nodcc4me]

Alan, I actually have an old 1A fuse, but getting it to stay between the couplers is impossible. I think the fastest and easiest solution, since these two locos always run in consist, is to change the couplers and see what happens. Now the question is: "Do I still have any plastic couplers"? 

[Alan]

[nodcc4me]

That would work. I'll give it a try.