Hi,
In my preparations for the upcoming train show in Helena, Montana in April, I pulled out our Bachmann Spectrum, Eureka And Palisade 4-4-0 to lubricate and test run so kids can operate it at this show. I am using an MRC THROTTLEPACK 9950 on our small one track train layout and had no other cars, engines, switches (12 × 16 foot oval only) or shorts anywhere on the layout.
I have the regular DC positive and negative wires with a 4 amp (manufacturer suggested) in line fuse on one wire.
The power pack was set on G scale and has never had any previous issues.
I decided to test run the locomotive first, however upon application of power it blew the fuse 3 times in a row.
I then checked and double checked the track, locomotive and wiring to no avail.
I could not find anything wrong, not even a derailed set of wheels. (The locomotive was the only item on the track)
After careful inspection and checking all the settings, I attempted to reapply power and heard a very loud pop and observed heavy smoke coming from the bottom and front of the main drive. (especially between the 2 main drive wheels)
I automatically assumed the worst, that the motor had burned out and the locomotive was a complete loss.
Now, here’s the kicker! I tried reapplying power and the locomotive ran perfectly fine. There was no hesitation, additional amp draw, loss of feature (like lighting and smoke) and no loss of power.
The locomotive continues to run perfectly without any further issues. There isn’t even any electrical smell or melted plastic anywhere.
I have never experienced anything so odd as this, so I wanted to bring the subject up to the forum and see if anyone here has ever had this experience with this locomotive (or others) or had any technical knowledge of the cause.
Also why does the engine continues to run and is there a potential for further issues down the road? These engines are a bear to dismantle and I would hope it wouldn’t be necessary.
I don’t know if there is a DCC board in that section of the drive that may have burned up or something else that has no direct effect on the operation of the locomotive.
Maybe someone has taken one of these locomotives apart and knows more about this issue.
I know a lot of folks who understand electronics may know what happened.
I have some knowledge but this one is a little beyond me.
Appreciate any help or info.
Thanks! Ken
Imagination Station Kids On Track
Ken
From the location you describe, it is likely the motor area
I believe there is a set of capacitors and inductors in this area for motor RF suppression.
My best guess it that you burned up a capacitor If so you will not see any difference.
Stan
Look at the end of the motor where the noise caps are soldered, if one blew up (a good guess) it would look burned or exploded.
Greg
Stan, Greg,
Thanks so much!
I guess my next question is why would that part/s burn out and nothing else? Is it possible they were soldered improperly or just a bad part that overheated?
Ken
Some (as in a few) of the Spectrum 4-4-0 and 2-6-0 locos had one or more 47 mfd electrolytic caps soldered in the wrong way around on the “noise” suppression pcb mounted on the end of the motor. The locos would run just fine in one direction but not the other. A cap would blow exactly like has happened now. Then, once the magic smoke had been released and the cap was out of the circuit, they would come good and run as per normal.
However, if that particular loco had at one stage performed properly in both directions, it is a trifle unusual for a cap to blow now.
Nonpolarized caps can blow too, just from being cheap or underrated.
As Stan and Tony have said, normally once these short circuit, the heat vaporizes the conductive path, and the short is gone for good.
Greg
Tony, Greg, Stan,
Great information!
I think it will run fine w/o replacing that part, hopefully!
Thanks for explaining it so it could be understood so easily.
Definitely gives us some reassurance.
Appreciate all the help!
Ken