Engines speed slowing down

[Alan]

Good to know you resolved the issue.

Your theory may be correct. Not so much the current goes up as the voltage goes down but rather the LM extending the pulse width to compensate. Eventually the LM is running at 100% pulse width making a lot of heat. Although one would think the LM would report over-current just before shutting down. And the sound continuing to play deepens the mystery.

I have a little dollar store hand vacuum the wife was going to throw away because it has so little suction. Turns out to be just the right amount of suction to clean track without sucking up everything around it. With the round brush attachment it only takes 5 minutes to vacuum the whole layout. Because I spend 99% of my time working on the layout and only 1% of the time running trains on it, it has become habit to vacuum before each use.

[William Brillinger]

I'm sure the keep alives are a factor in things continuing to run, as they discharge, things get slower but they should only go for about a minute. In some circumstances when a warning is thrown the loco may need to be removed from power to reset the module. it's possible that the reset happens on it's own after some time elapses - this may be the 15 minutes.

[G8B4Life]

Well thanks to work (which was appreciated!) I got home so late I was so tired I didn't turn the PC on for a day and a half so missed the start and apparent conclusion of this conversation. I know you said you found the problem but I'll reply as I think dirty track/wheels is only one part of the root problem.

To me it also sounds like something is overheating. Addressing the first obvious culprit, the motors, the LM wouldn't report the motor getting hot, it has no sensor for that. All you could do is monitor for the over current warning on the HC. I don't think it's any of the motors overheating.

The second obvious culprit, the LM, has pretty much been ruled out as no warnings applicable to the LM (pretty much the over temp warning) were given.

This leads us to the possible third culprit, the power supply. The symptoms given all point to a failing power supply (or possibly one that is being driven too close to it's maximum rating for too long); this is a sudden onset problem after years of no trouble, it affects 7 locomotives that had no issues that then all experienced the same issue in the same time span, you get the low voltage warning a couple of minutes before everything stops and after about 15 minutes (ample cooling time for the power supply) everything works again (the sound may keep on going because of the keep alive. The sound continuing to play is the only bug in this argument).

What power supply are you using? I'd seriously check it for any signs of failing/failed components, and if you can monitor the voltage and current draw at the power supply. Depending on the type of power supply you have you may even be able to cool it with a fan and see if trains run longer before things shut down.

- Tim

[SWA737]

 That makes sense on the  module reset Bill and thanks Alan for the thoughts on the vacuuming. My shop vac has too much suction so the one you’re using sounds like a great idea.

[SWA737]

 Thanks Tim on your reply.  I have four power districts of which all four are using the Ring engineering power supplies. They are not hot  to the touch and when I started having this problem, I was only running a couple of locomotives at a time. I isolated all the staging tracks electrically so no power was going to any of the other  locomotive  keep alives for charging. Don’t think it was any kind of overload on any of those power supplies. I cleaned some track in key areas last night and discovered that was the real problem. A bad overlook on my part.

[G8B4Life]

Well having four separate power supplies would seem to rule a failing / over loaded power supply out as the root problem. That would bring us back to the LM or the motors.

After the loco's stopped how long did the sound continue play for? less than a minute? the whole 15 minutes stopped time? Just wondering.

I find it strange that if dirty wheels and track was the root problem that you could repeat the situation (run 10 minutes, slow, LV warning, stop, wait, run 10 minutes, slow, LV warning, stop, wait ad infinitum) without the run time before the slowing, LV warning and finally stopping getting progressively worse as the wheels etc dirtied up more and more each time.

- Tim

[SWA737]

 I only left the locomotive on the track for maybe 30 seconds after the motor stopped with the sound going. Don’t know how long the sound would have run.  I will keep you posted on what goes on with it. Will not be able to work on it any today. Thanks for your help Tim.