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Discussion Starter · #1 ·
Hi All,

I found a pretty simple way to repair the thin power pickup wire on the non-uni side of the bachmann/aristo ball bearing motor block (the newer style block installed on FA/FB units, RS3's, U25B's, eggliners, etc.). This wire tends to melt as it is way under gauge, then power pickup is severely degraded when this happens. This particular repair I performed on one of my eggliners, and have a few other blocks (not mine) in line to repair after this.

Simply took 26ga stranded copper wire - stripped it back quite far and rolled it into the channel that the ball bearing sits in. I was sure to strip it back far enough so the wire insulator would not pinch when putting the block halfs back together. Then I ran it up to the power pickup "terminal" screw, stripped the wire back, looped it under the screw and retightened it down. Then rinse and repeat on the other side. Well, here's a picture that will show it better than my text above:
Circuit component Hardware programmer Gadget Computer hardware Electronic component


Simple but effective repair. Hope this helps someone out!
 

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Did the wire itself melt, or did it head and "submerge" into the plastic?

By the way, this almost exclusively happens when you have a derailment and the loco sits there for a while, and the short is conducted through this wire.

Greg
 

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Discussion Starter · #3 ·
The wire on one side was melted. I do not recall this eggliner ever derailing/shorting the rails. It is my kiddos eggliner, but I'm around when it's running. I also have been using revolution trackside which is VERY quick to shut things down if it senses a short. I just started noticing poor power pickup, and suspected this melted wire as I've seen it on other aristo/bachmann ball bearing blocks.

As for the other one on my bench to fix (RS3, not mine), I was told it was just running along happily and started smoking. Anyways, I discovered it has the melted wires on both blocks AND broken brass strips that go to the universal (no doubt stress from the flexing). I'll be coming up with a fix for that.

Derailments shorts are possible, but I'm wondering if there is a situation where the power pickup from the universal side is degraded, all of the current shifts to running through those small wires towards the rear resulting in burnout (like a fuse).
 

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OK, the wire itself was melted.. I'm assuming you mean it was no longer continuous, melted metal. This can ONLY happen from a derailment, because only excessive current will melt that wire, under normal conditions it is sufficient to carry current, the motor block does not pull a lot of current.

It takes a very large amount of current to do this, and unless the motor is a dead short itself (and of course you would know that), then it is a short, between the front wheel and the rear wheel on one side. All the short circuit current flows through that wire. That's the only way you can get enough current to melt a solid copper wire.

This is a very common occurance on a derailment, usually on a switch. One wheel is on the outside rail, and the other wheel has touched the moving points, which are opposite polarity.

Even if all the current came from the other axle set, (the brass strips are not working) it's still not enough. There are possibilities, but they would alert you. For example, a damaged motor drawing abnormal current could still run but draw several amps. But you would notice the current draw most likely, and the loco would run weird.

I've read all the forums for 20 years, and you have somehow put excessive current between the 2 wheels on the side with the melted wire. The fact this keeps happening tells you something.

RS3? Yes it has some other issues internally, the internal power regulator can short and melt stuff. On the RS-3, usually the circuit board traces between the front and rear trucks is sacrificed from a derailment.




There are thousands of these in service, and your issue is not common.
 

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Discussion Starter · #5 ·
Not just my issue, as I have seen it on at least three blocks recently (one being mine). I'm certain there are others out there faced with this problem (derailment/short or not, we can argue the cause). But fact is, "common" or not, this issue exists on more than just my one eggliner block. Maybe this simple repair will help someone out in the future when they discover they have this same issue.
 

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Yes, it will help others. Often what happens is the wire gets hot, and melts down into the plastic. It's still there, but you cannot see it. Often this has the byproduct of "gluing" the motor blocks together.

A better solution is to add the PolySwitches that Aristo started using later, this will limit overload current flow and stop this from happening in the first place. It won't stop the cause but it will stop the damage.

I advise everyone that if they have the loco open, to add these.

By the way, you actually have seen 3 motor blocks with the wire melted, and again, the wire is "broken" definitely, or just melted into the plastic. I've seen the latter a lot, but never the wire itself melted.

Greg
 

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Discussion Starter · #7 · (Edited)
Yes, it will help others. Often what happens is the wire gets hot, and melts down into the plastic. It's still there, but you cannot see it. Often this has the byproduct of "gluing" the motor blocks together.

A better solution is to add the PolySwitches that Aristo started using later, this will limit overload current flow and stop this from happening in the first place. It won't stop the cause but it will stop the damage.

I advise everyone that if they have the loco open, to add these.

By the way, you actually have seen 3 motor blocks with the wire melted, and again, the wire is "broken" definitely, or just melted into the plastic. I've seen the latter a lot, but never the wire itself melted.

Greg
Greg,

I've seen three with the wire itself melted so far (not just imbedded into the plastic). I expect to see more soon.

As for the poly fuse, installing it internally to the locomotive will help save the internal boards for sure, but it won't save those little pickup wires in the motor block in some instances (for example, if there is a direct short between the front and rear wheel on the same side of the same motor block). You'd have to fit a poly fuse on each side of the block itself where the little wire is going up to the terminal (before it connects with the terminal). There just isn't really much room there to fit poly fuses, but I guess it might be possible.

FYI - the Eggliner I made this repair to has run successfully and really well all day (literally from 7am until 10 pm) for the last 4 - 5 days. We're talking a good 60+ hrs of runtime now which is actually more than it had run total collectively before this fix (we're using this Eggliner around the tree right now to guard the cat from getting into the tree and damaging the branches/knocking ornaments off. As long as the Eggliner is running, the cat stays away from the tree 😅)
 

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Wow, so many many of these have been used, Aristo outsold Bachmann and USA Trains in this area (2 axle diesel blocks).

This is not a common issue, and other than severe overload, it HAS to be a short between that axle served by the wires and the other axle or the other truck.

Normally you will burn up traces on the circuit board inside when there is a severe and prolonged short between trucks.

Yeah, I meant a polyswitch (actual name) to protect that wire, would have to be done internally to the motor block. Putting them inside the chassis will protect from truck to truck shorts, which are also common.

Greg
 

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Discussion Starter · #9 ·
I'm going to see how this fix continues to hold up. I know another weak spot (that I mentioned with the two other blocks above) are the universal axle brass contacts (where they sandwich into the uni housing). Over time and so much flexing they are stress fatigued and then crack. I have other ideas/possible solutions to fix/improve that, but I want to flesh my ideas out before I mention what they are....

Also, I hear you on the number of these that are out there, and supposedly the lack of reporting on this issue. But I SERIOUSLY suspect more folks have this issue than realized. If the track is reasonably clean, and the uni axle pickups are still intact (not cracked), the block will keep running (especially if it is a two-block locomotive, since you'll have pickup shared between the two). Why open the block up if it is still running..... for most people the performance is ultra degraded before they even start to notice that there is even anything wrong.
 

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So just my observations. I zoomed into the original picture and circled bare wires close to motor.
Coil Auto part Technology Cable Wire

Might put some heat shrink in that area.
 

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Discussion Starter · #11 ·
So just my observations. I zoomed into the original picture and circled bare wires close to motor. View attachment 62826
Might put some heat shrink in that area.
Thanks for the feedback, but the heat shrink is not needed. There is a small channel there that the wire sits in. With the block sandwiched together properly there is no way the wire is going to touch the motor. In fact, if you look at the original OEM design, there is a BARE wire that runs the entire length..... in the channel RIGHT next to the motor. You can see if if you zoom in. In the areas that could possibly touch the motor, I of course left the insulation sheathing of my replacement wiring in place. Plus, heatshrink there would be too thick to allow the proper "sandwiching" of the motor block when reassembling. In fact, the wire insulation itself was too thick to allow for proper "sandwiching" of the block halfs, which is why I stripped it back so far to begin with.
 
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