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Athearn Electrical Pick Up Issue

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Espeelark:
I'm at my wits end guys....

I have installed LM-3S modules in 3 locos so far. Two Athearn and one (red box) Atlas. I've hard-wired all three.
While the Atlas U30C runs great, both the Athearn GP40X and SD40T-2 have significant electrical pick-up/continuity issues. The locos move only a hair and then die, then re-start, move, die, re-start, etc., etc., etc....
See the attachment for a photo of the hardwired LM-3S module and iphone speaker in my SD40T-2 unit.
NOTE: I don't have "Keep Alives" installed and was hopeful to NOT have to use them because my staging yards on the layout I'm building has optical sensors between the tracks that kills the power to the track(s) when the train gets to the end of the track. KA's would circumvent that and the train would keep on rolling....

I did numerous interweb searches on the issue and there was quite a bit of concensus around poor electrical pick up between the metal sideframes and the square, bronze bushings on the ends of the axles due to the chemical blackening Athearn uses on the sheet metal sideframes.
I used a very fine emery board and sanded off that "skin" of chemical blackening on the slot faces in the sideframe where the bronze bushings sit. I then used a cotton swab dampened in WD-40 (non-polar cleaner) the clean all of those surfaces.
See the attachment for a photo of the metal sideframes at issue.

One the test bench, I can just touch/move one of the trucks slightly and the unit loses power as the engine sound cuts out. Or, I'll slightly pick up one of the trucks and it will lose power. I'm at a loss why it loses power since the other truck is still firmly seated on the rails. The SD40T-2 has six axles making electrical contact so why does a slight "jiggle" of one of the trucks cause the whole thing to lose continuity?

It shouldn't be this hard.....

Alan:
WD40 has a high dielectric strength on the order of thousands of volts. Exactly the opposite of what you want for electrical continuity. Re-clean with IPA or contact cleaner and try it again.

Espeelark:
Hi Alan - thanks for the thought.
There's been a lot of discussion about what to use to clean track. MRH had an article in their May 2019 issue going into great length and Polar vs. Non-Polar cleaning agents. WD40 is one of those items that has a lower dielectric constant (2.4) rating it as a non-polar agent good for cleaning rail and electrical contacts. IPA has a dielectric constant of 18. I have a friend who has a Doctorate in Electrical Engineering and he agrees with the use of Mineral Spirits or WD-40 for cleaning rail, etc. If you read that MRH article you will see that alcohol is not recommended.
I may try again with mineral spirits but am not hopeful as that has a similar dielectric constant to WD-40. I'll report back.

Alan:
There is a big difference between wiping on / wiping off (track and wheel) and spraying on / evaporating off (your application).

You are referencing the dielectric strength of the liquids themselves. I'm talking about the dielectric strength of the residue the WD40 left behind. WD40 is not 100% volatile. The dielectric strength of IPA or contact cleaner is irrelevant. What is relevant is they are 100% volatile meaning they don't leave a residue when evaporated off.

G8B4Life:
I can't see anything obvious in the small photos. Are you sure they actually loose power and it's not intermittent shorting?

I remember a run of models (not US) that had the same setup for electrical pick up. Unfortunately not only did the metal "sideframe" have the bearing slots coated like you found but the metal they were made from was just crap quality too and solder didn't really want to stick to the pickup wire tab very well. If it's not intermittent shorting and they are loosing power then I'd look for loose joints.

I also remember reading somewhere where someone had gone and eliminated the metal sideframe from the equation and soldered the pickup wires straight to the axle bearings.

- Tim

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