Atlas GP38 with Intermittent DCC Troubles

[Dwight in Toronto]

Peter - the last time I tried sending a decoder back to ESU was not that long ago - it was that 58741 board that had been acting up with the Kato ES44AC (the one in which I replaced both the motor and the decoder).

Because I didn’t have the original receipt, ESU said that they would charge $80 US in exchange for the old decoder.  They told me this after they gave me a return authorization, and after I had put the unit in the mail.  Regardless, the package was eventually ‘returned to sender’ two weeks later by Canada Post, with some sort of Customs rejection.  I think it was because there was nothing on the package indicating what the contents were.  I mailed this thing at a Canada Post office, where I explained what I was trying to do to the postal clerk who was helping me, so I had faith that all was good & proper.

I think I have the receipt for this particular decoder, but for $139 Cdn I can just order another one from my local supplier, avoid the interaction and delays with both the post office and ESU, and I’ll have it within 2 or 3 days.  No big deal.

Thanks to all for your interest, help and suggestions.


 

[GGNInNScale]

Hi   One thing I do is to tin the contact pads on the 58741 and 58751 decoders.  Then, I clip the two bronze motor contacts a bit to shorten them.  Then, I cut a wire about 1 cm long and about 8 mm long, trim the insulation and tin the ends.  Then, I tin the tips of the bronze contacts.  Then, solder the wires to the bronze contacts.  Wrap a bit of Kapton tape around the frame area where the contacts come up to the top region.  Then, put the decoder almost into position at an angle so you can just solder the two wires to the two pads, shorter one first, then the longer one.  Then, carefully lower the decoder making sure the wires are not pinched, and slide into place.  This makes a solid connection to the motor, and the slide contacts toward the front are also good.  Then, change the front and rear lights to AUX1 and AUX2, respectively in the decoder programming section.  You can remove the Front Light and Rear Light assignments if you want, but not necessary.  I just did one this morning, but as usual, forgot to take pictures...

[Dwight in Toronto]

Just an update … a new ESU 58751 ‘Atlas’ sound decoder arrived today (along with a Lok Tester - I finally decided to acquire one).

Oddly enough, I’ve been running that ‘troublesome’ decoder at least two hours a day, every day, since I swapped decoders a week or so ago.  The first few times it briefly emitted that high frequency buzzing as the NCE booted up, but quickly quieted down and would run fine.  It hasn’t even been buzzing lately.  Of course, as soon as I put the shell back on, it will probably act up!

Anyway, I’m going to hold off installing the new decoder until the next time things go awry.

[GGNInNScale]

Another thing you can try- take some Caig DeOxIt or similar.  Spray it liberally into the motor wherever you can see an opening.  This stuff will not hurt anything in the frame or motor.  Run the engine while the goo is still wet.  This will clean up the brushes.  Then relube the bearings with LaBelle light oil.

[Dwight in Toronto]

As has been my routine since this ordeal started, I was again letting both locos do endless loops with one running on the inner test oval and the other on the outer.

After 15 minutes or so, the older Atlas chassis with the newer 58751 decoder (as per the swap done a week or so ago) suddenly developed the old familiar problem - very slow, hesitant, jerky crawl, irrespective of NCE speed step setting.  This suggests to me that maybe this is a motor problem after all. 

Just for the record, the older decoder in the newer chassis has thusfar been trouble-free (apart from that tendency to emit an occasional, short-lived high frequency buzz when the NCE boots up - the noise quickly stops and the loco can be operated normally).

GGNInNScale - at this point I’ve got nothing to lose by trying something like you suggest.  I don’t have DeOxIt, so I’m curious to know if there might be a few other things that might work comparably?

Another option is to see if Atlas might have replacement motors.  For those who remember my similar experience with two Kato locos (an ES44AC and an AC4400), this whole thing feels like deja-vu all over again!

[GGNInNScale]

Hi  I also use CRC Electronic Contact cleaner (just a lot larger can than the DeOxIt).  Works the same.  You can get it at hardware stores.
https://www.crcindustries.com/qd-174-contact-cleaner-11-wt-oz/

[peteski]

In general I'm not a fan of using electronic contact cleaners in the way described.  Many contact cleaners also contain lubricants which remain after the cleaner evaporates.  Commutator and brushes are supposed to operate oil-free (dry).  The graphite (carbon) in the brushes acts as lubricant. If there is an oily film on the commutator, it can cause the powder from brushes wearing down to accumulate in the gaps between commutator segments, causing problems with the motor.

When I have motors which need full cleaning I dunk them in an ultrasonic cleaner filled with Naphtha, which is a good solvent for lubricants and it leaves no residue.

Dwight, remind  me how you fixed the  other loco you have with a similar problem (twitching motor which had to be "kick-started")?  Wasn't that loc made by Kato?

[MK]

I agree with Peteski.  For example DeOxit leaves something behind to prevent further oxidation going forward.

If you really want a spray motor cleaner, go to a LHS that sells RC cars (or order online like Tower Hobbies) and get a can of spray motor cleaner.  They leave no residue.  As a matter of fact, they tell you to lube the bearings and moving parts after use.

[Dwight in Toronto]

Peter - with that earlier (similar) experience, where we were swapping boards and investigating one of the motors in those two Kato locos, I ended up throwing up my hands, and simply installed a new motor and a new 58741 board.  Both locos have been operating fine ever since.

I still have the old Kato motor and ESU decoder, and intend to revisit them ‘one of these days’.
Maybe I’ll try out my new ESU decoder tester with that old 58741.

Thanks guys, for the advice re: motor cleaning.  Makes sense.  The alternative is to try to clean the contacts through the brush ports as Peteski once described, but after what I went through, removing & losing brush springs etc with that Kato motor, I’m not too keen to dig into the Atlas unit. 

I browsed the Atlas parts diagrams and spare parts inventory.  Atlas GP38-2 motor = “motor/flywheel assembly 489100”; for the GP40-2, it’s #486100.  However, neither motor was shown in the parts listing.

I’ll try emailing them and asking about cost/availability.  Other than that, I’m not sure where else I can take this investigation.

[peteski]

Dwight, the decoder tester  comes in very handy for testing all sorts of decoders which have connectors for hookup, but with the type of decoder here, it isn't all that helpful since you still have to attach/solder wires to the pads on the decoder in order to connect it to the tester using the individual wire terminals.  The only difference will be that the decoder will be connected to a small coreless motor instead of the "standard" Atlas motor.

I'm also wondering if somehow the NCE Power Cab is contributing to the problem (the buzzing you hear when Power Cab powers up).  Have you tried running the misbehaving locos for extended period using the LokProgrammer's virtual driver's cab?

[Dwight in Toronto]

Thanks Pete.

Yes, I knew when I ordered the LokTester that ESU’s drop-in decoders would require more work to hook up to it.  But you know, for only $58 Cdn, there’s a lot of nice componentry, PC board engineering, flexibility and utility in that little device; it is truly an affordable nice-to-have.

My LokProgrammer is two floors away from my workbench, and I don’t have a computer in the train room, so I haven’t done any continuous running in that manner.  I suppose the NCE could have a quirk, but it is only that one Atlas loco (the newer chassis with the older decoder) that exhibits that buzzing behaviour, and not every time.  I suppose I could set up a small circle of Kato Unitrack in the spare room where the computer is, and let ‘er rip, but it would be a bit awkward.  We’ll see.

[milw156]

hashtag unsponsored, Streamlined backshops offers a "caddy" to allow testing the drop in boards with a Lok programmer, Disclimer: I have never used this item

https://sbs4dcc.com/products/sbs4dcc-esu-53900-loktester-decoder-test-module-add-on-kit-for-58721-58731-58741-mx605-mx660.html

[Dwight in Toronto]

I browsed the Atlas parts diagrams and spare parts inventory.  Atlas GP38-2 motor = “motor/flywheel assembly 489100”; for the GP40-2, it’s #486100.  However, neither motor was shown in the parts listing.  I’ll try emailing them and asking about cost/availability.  Other than that, I’m not sure where else I can take this investigation.

Update - I went to the “contact us” segment on the Atlas site and submitted a question on replacement motor availability.  I received an email reply the very next day, informing me that the motor is $35 and shipping to Canada is $18.  This comes in at roughly $75 Cdn, so it’s a wee bit pricey.

At this point, I may as well just try the contact cleaner, see what happens, and report back to the group.

Just for the record … the loco once again went into “erratic limp-mode” just a few hours ago. 
As usual, a quick kick in the a$$ with a jolt of DC, and she was off and running on DCC, as if nothing untoward had ever happened.  Strangest friggin’ thing.

milw156 - thanks for the info on SBS adapter kits.  I did see that some time ago, before I bought the LokTester.  It would be good to hear from anyone on TRW who may have tried them.

[Dwight in Toronto]

Continuing with this saga.

I finally got around to trying the spray contact cleaner on the Atlas motor.  I removed the motor from the chassis, pried off the brush caps, removed the springs, and tapped out the brushes.  Well, one of the brushes … the other one wouldn’t drop out.  As I was tap-tap-tapping to try to eject the brush, a noticeable amount of black powder was speckling the workbench (obviously graphite - black, slippery, pencil-like streaks).  I put a tiny speck of CA on the tip of a toothpick, held it momentarily against the top edge of the brush, and then extracted it.

Both brushes were in good condition, plenty long enough, and from what I could see, the commutator was clean shiny copper.  Nothing untoward; no graphite dust came out of the brush cavities.

I soaked the entire motor with the cleaner, making sure to fill the brush cavities. I spun the flywheels, blew everything out with compressed air, and repeated.  I then put the brushes etc back together, soaked the motor again, and spun it up & down on DC until everything was dry.

I then jumpered the motor leads to the 58751 decoder, and tried it on DCC.  Horn, bell, lights all worked, but the motor didn’t budge.  Finger-flicking the flywheels would only get one rotor rotation.  The motor would not run irrespective of speed step setting. 

Enough!  I’m ordering a new Atlas motor.

In the meantime, I did try one last thing.  Some time ago, I had a similar problem with a Kato loco (I know that Peteski remembers that incident).  I ended up replacing that Kato motor (it was an ES44 mechanism), but eventually managed to get the old Kato motor running again.

Just out of curiosity, I compared the Atlas and Kato motors.  Surprisingly, they are pretty much identical.  So, with nothing to lose, I removed all four flywheels, and managed to get the smaller Atlas flywheels onto the Kato motor shafts. 

I put the Atlas loco back together, soldered the orange & gray wires to the Kato motor leads, and was happy to see it running once again on DCC.  The only problem - it’s noisy.  Kinduva “wa-wa-wa” sound that varies with speed.  I don’t see any friction or binding anywhere; the drivetrain moves nicely when flicking the flywheels manually, and the loco crawls effortlessly on spd step 1.

So, I dunno, but - no worries - swapping flywheels etc was good experience, and it was satisfying to see the Kato motor functioning in the Atlas chassis. 

I’ll report back, presumably one last time, when the new Atlas motor arrives and gets installed.

[peteski]

Glad to see your model fixed.

Atlas motors are basically Chinese-made copies of Kato design. This happened when Kato and Atlas parted their ways and Atlas likely gave the Chinese factory some Kato models to copy, since some model examples were first made in Japan (Kato), then in in China.  Atlas versions for the Kato models are also almost (but not totally) identical.

Atlas motors are not identical in constructions but all the dimensions are basically the same. Atlas motors also have skew-wound armature (Kato's is straight).  Try putting some light oil in the motor bearings to see if that will take care of the noise.