Tomix 115 Running Jerkily

[CaptOblivious]

Here're two diagrams.

 

No. one: This is a connect-the-dots diagram showing the flow of current through the model. The model is symmetric, so the left side (which I have not labeled) works just like the right side. For this configuration to fail, any two of the four springs on one side (top or bottom, including the trucks) must be failing to make contact. So the design is pretty robust.

 

Notice that this diagram also explains why you saw no voltage across the interior light terminals! It's because the interior light is in series with the motor. There would be a voltage drop across those two contacts only if it were wired in parallel (which most interior lights are). So, that small mystery solved.

 

No. two: This is a connect-the-dots diagram showing the flow of current if an interior lighting unit were installed, and the two frame (not truck) springs on the right-side of the photo were removed. Notice that for maximum reliability you should leave the springs on the left side intact, although the lights would be brighter if you took all four out. If you left all four in, the lights wouldn't really burn at all.

 

So, if in fact there is a spring failure, then installing an interior lighting unit would fix it (since some of the springs have to come out for the light to work!). If you don't have a Tomix interior light of the right configuration, then simply jumping the two terminals in the plastic "O"s on top of the chassis cover should fix the problem.

 

*crosses fingers!*

[scott]

Wow--thanks for all the time and thought that went into that! If I had had to figure all that out on my own, I would have had to just buy a new chassis or something.

 

I don't have a lighting kit, so for now at least I can try to rig up some sort of wiring to jump the two holes in the chassis cover.

 

In the longer term, I'd like to get it put back right, but I'll need to find a source for tiny brass springs. (Those things have about zero mass--I managed to drop two of them yesterday, and was very lucky to find them at all after they flew away.)

 

I'll fiddle with this over the weekend and see what I can do.

[cteno4]

Yeuch,

 

Unfortunately, this uses the same spiral wire drive shaft that the de10 model uses. from what i have found dealing with Aaron's jerky running de10 some of the problem is the fact that the drive shaft is flexible it will want to fly out at the end (sort of propeller) and thus rubs a lot in the end sockets and if these are slightly out of line then it can cause it to hang up. I found that there was definitely an orientation to the to the end sockets on the de10 even though they are identical parts! also at times on re-assembly the unit would run jerkily even when i hooked the power directly to the motors.

 

Aaron's de10 motor also took some abuse and i think there may be a bit of metallic grit stuck on the magnets between them and the rotors. when running the motor by itself it required a lot of current to run smoothly. i cleaned the pickups and brushes in the motor and cleaned it as good as i could w/o doing drastic cleaning measures (now that he has a new replacement motor i can try some of these techniques to see if any work well to overhaul a motor acting like this). it now runs pretty well, and i was able to get it running smoothly re-assembled, then Aaron took it home and it ran smoothly for a short while then back to the old jerky and dead behaviors!

 

so you may be getting current fine and it might be either the drive shaft binding up some or the motor sucking in some grit. this causes it to get just stuck enough to not turn over, but when you open it up it is unstuck.

 

it is a bit of a mystery to me. i did all the troubleshooting that the the folks below suggested and more to trace the power, as that was my first guess, on the de10, but after fiddling with it for several hours i started to think it was just the thing getting a bit out of alignment.

 

i also wonder if the drive shaft end housings eventually get a groove worn in them that causes them to hang. also want to do the ultrasonic cleaning on them in case there is a bit of grit stuck up inside them. when i tried to clean them out by hand the system seemed to work better.

 

ill post more when i get aaron's new motor and de10 to play with, first will try to clean the old one throughly (knowing that we have a new motor in reserve now!) to see if that can fix things.

 

cheers

 

jeff

[scott]

Thanks, Jeff.

 

I'm starting to wonder if it wouldn't be easier (if cowardly) to see if there's another power chassis that this car-body would fit.

[cteno4]

Scott,

 

i know its frustrating! i kept fiddling with aaron's de10 and it would work fine then not! finally thought i had it all fixed and got it to aaron only to have it go a couple of laps and then started misbehaving again!

 

wait till i give the ultrasonic cleaning on aarons a try and see if that does anything!

 

greenmax makes some chassis that are fairly standard sizes...

 

cheers

 

jeff

[scott]

Thanks to Bill's suggestion elsewhere, I now have new innards for the 115, and it just took a perfectly smooth test run around the layout!

[CaptOblivious]

Outstanding news, and cheers to Bill!

[scott]

Just resurrecting this old thread to say thanks again to Bill--the 115 has been happily circling the Christmas tree for about an hour now, without a hitch.

[bill937ca]

Just resurrecting this old thread to say thanks again to Bill--the 115 has been happily circling the Christmas tree for about an hour now, without a hitch.

 

Good news!!