short circuit in tomytec chassis

[EF57]

I wanted to run two trains on my double test loop.  On putting the first, with a tomytec power unit TM 10R, on the track, its wheels started spinning.  I put it down (not dropped) and turned the power to zero.  Then I put on the other train and ran it — everything OK.  But when I put the tomytec back on, it would not run, was shorting out. Still doing it, both directions, alone on the track.  It used to run perfectly.  Wtf?  How can this be?  No visible damage or change from before.

[cteno4]

So it was the Tomytec you put the wheels on the track with power on and they spun? Is this brand new or run before?

 

tried wiggling the trucks around to make sure seated properly into the chassis and no truck power pickups stuck?

 

try popping the mech pit and spinning the flywheel or drive shaft some and make sure things turn well for a bit then try power.

 

I’ve never had a Tomytec mech die like this. Next would be opening it up.

 

jeff

[katoftw]

I would check the lead weights and copper strips are all still in there correct places.  I'd hazard a guess that these are touching if there is a short present.

Edited March 25, 2019 by katoftw

[cteno4]

Good point kato

 

jeff

[EF57]

I tried all that stuff, nothing helped.  Jiggled the weights, jiggled the copper strips.  Each truck individually still shorted out.  But it’s such a simple mechanism, I kept saying to myself, it can only be a simple contact problem, so I kept at it.  I eventually got mad at it, so my jabs with the screwdriver got progressively more aggressive.  One hit on a metal strip, and suddenly it was running perfectly, as before!  Thanks guys!

 

I really don’t see how the short happened, as I did not drop the unit or anything, just put it down on the table.

 

PS Jeff:  Just how does one “pop the mech pit”?  (cool terminology)  I couldn’t get the cover off.  Would be useful to know for future problems.

[cteno4]

hey glad its working. sometimes just fiddling makes it start working and you dont know why and it can be frustrating. 

 

whoops the "pop the mech pit" was an auto correct, i think i meant "pop the mech out" (of the shell). most all of the tomytec mechs you can turn the flywheel or universal joint or axle to make sure the motor and all the gears are turning and that a motor brush has not ceased up and shorted out.

 

ive never completely disassembled a tomytec chassis (never had a really bad failure on the twenty odd i have), just different bits on different models but they are all pretty similar. nothing comes to mind that would short out like this. kato's suggestion of the weights did sound like something to look at as the do rattle around a bit on some and there are exposed contact strips, but again ive never paid that much attention to the tomytec mech design. 

 

when you say each truck individually shorted out, do you mean applying power to each showed a short on the transformer? if so thats because any short in the whole circuit in the chassis will show up on either truck (unless one of them is loose and not making contact to the chassis circuit).

 

have you run this one much? if not i would give it a 20 min burn in run. 

 

cheers

 

jeff

[nah00]

It's possible from manufacturing you had a sliver of metal stuck in there. Also possible that there's a bad spot on the motor and jiggling the chassis a bit more you moved past it. Also entirely possible that the explanation was 'it just didn't want to work', I'v had locos stop working and then work fine for no reason at all.

[EF57]

yeah it’s the metaphysics of model trains ...