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RailPro => RailPro Specific Help & Discussion => Topic started by: nodcc4me on February 21, 2020, 05:46:16 PM

Title: Consisting Problem
Post by: nodcc4me on February 21, 2020, 05:46:16 PM: 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?
Title: Re: Consisting Problem
Post by: KB02 on February 22, 2020, 05:02:23 AM: 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?
Title: Re: Consisting Problem
Post by: G8B4Life on February 22, 2020, 06:07:37 AM: 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
Title: Re: Consisting Problem
Post by: Alan on February 22, 2020, 08:39:52 AM: Is either locomotive by itself real close to the maximum LM current to begin with?
Title: Re: Consisting Problem
Post by: nodcc4me on February 22, 2020, 08:50:27 AM: 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.
Title: Re: Consisting Problem
Post by: Alan on February 22, 2020, 08:54:48 AM: What happens if you physically turn one loco around the opposite direction and then couple together?
Title: Re: Consisting Problem
Post by: nodcc4me on February 22, 2020, 09:08:28 AM: I linked them both in the forward direction and they ran without error. What does that mean?
Title: Re: Consisting Problem
Post by: Alan on February 22, 2020, 09:17:03 AM: Your motor leads are not electrically isolated from the loco frames.
Title: Re: Consisting Problem
Post by: nodcc4me on February 22, 2020, 09:30:24 AM: 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.
Title: Re: Consisting Problem
Post by: Alan on February 22, 2020, 09:41:01 AM: 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.
Title: Re: Consisting Problem
Post by: Alan on February 22, 2020, 09:48:04 AM: 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?
Title: Re: Consisting Problem
Post by: nodcc4me on February 22, 2020, 09:50:54 AM: I'll try the fuse later and report back. I appreciate the help.
Title: Re: Consisting Problem
Post by: nodcc4me on February 22, 2020, 01:30:42 PM: 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"? :D
Title: Re: Consisting Problem
Post by: Alan on February 22, 2020, 01:38:34 PM
Title: Re: Consisting Problem
Post by: nodcc4me on February 22, 2020, 01:47:02 PM: That would work. I'll give it a try.
Title: Re: Consisting Problem
Post by: nodcc4me on February 23, 2020, 10:15:03 AM: I did the fuse test using a 1A fuse. Ran the current up to 16% and it did not blow. Of course, the Over Current error did not come up either. ??? Other than an intermittent motor wire short I guess there is nothing left to check, though I'm still not understanding why it only happens when they are linked.
Title: Re: Consisting Problem
Post by: Alan on February 23, 2020, 10:31:53 AM: Can't solve what you can't recreate.

Reproduce your steps again from the very beginning. Can you get the warning to reappear at any point? Then can you then repetitively create the warning on demand? What are those conditions?
Title: Re: Consisting Problem
Post by: nodcc4me on February 23, 2020, 11:25:43 AM: I went through several scenarios and have come up with the following:

Either loco runs perfectly by itself in both directions.
They run perfectly when linked, but separated.
They run perfectly when linked and connected and both are going in the same direction.
The problem only occurs when linked, and connected in opposite directions. Then either one or both go over current.
There is no apparent electrical connection between them through the couplers.
Title: Re: Consisting Problem
Post by: Alan on February 23, 2020, 11:42:21 AM: What happens if you put a freight car between them?
Title: Re: Consisting Problem
Post by: nodcc4me on February 23, 2020, 12:24:28 PM: I put a car between them and set the original problem engine as the lead, running in a forward direction. They ran for at least 5 minutes with no errors. Then I reversed them and after about 2 minutes, as I brought them to a halt the problem loco went to overload. At that point I couldn't get it to run at all. Each time I reset it and barely moved the throttle it overloaded.
Title: Re: Consisting Problem
Post by: Alan on February 23, 2020, 12:51:17 PM: Do you get same results without the freight car? i.e is the physical connection of locos relevant to the puzzle.

Swap LMs between the locos. Does the problem follow?

If not you might ask:
Certain all internal wiring is away from spinning parts of drivetrain?
No possibility of a swaying bare wire touching at a connector or in wire run?
Truck wires insulated and free of interference?
Foreign fragment of metal moving around? For instance a single strand of a clipped stranded hookup wire in the motor brush area.
Title: Re: Consisting Problem
Post by: nodcc4me on February 23, 2020, 01:28:40 PM: I'm going to take a good look at all the wiring on that loco. The fact that the problem is intermittent leads me to think that is where the trouble lies. They do have to be physically connected, with or without a car in between, and they have to be facing opposite directions for the overload to occur. When facing the same direction, no problem. Pretty weird.
Title: Re: Consisting Problem
Post by: nodcc4me on February 24, 2020, 11:04:57 AM: I believe I've found the problem. One of the motor wires was rubbing on a flywheel and a tiny spec of bare wire was evidently touching it. I insulated that spot and now they seem to be running together happily. I'll do some more testing to confirm. Alan, thanks so much for all your good advice. :)
Title: Re: Consisting Problem
Post by: Alan on February 24, 2020, 11:35:07 AM: My pleasure. Enjoyable, like reading a good who-done-it novel with the last chapter missing from the book.