Atlas new run GP35

[thomasjmdavis]

Has Atlas found a slower slow motor?

Picked up 2 late November, installed Digitrax DN163A4 decoders, and started to tune them.
Found that I could not get the speed over 45SMPH.  On other runs of Atlas locos I have had no problems setting the speed curves to max-out at 70SMPH.

Did Atlas or Digitrax Change? 

One loco did show a marked increase in speed after about 10 hours of operation (45 to 68smph), but I have not seen this kind of change in Atlas loco since going to DCC in 1996.

The first question I would ask is whether the loco displayed this behavior when tested out of the box before the decoder was installed.  Obviously too late for this advice, but I try to deal with any mechanical problems before adding anything- even gluing on details, much less installing decoder or other electronics- so that if I have a lemon, I can send it back, without having "modified" it. I haven't had an out of the box issue with a new loco since the late 1970s, but sounds like they are coming back in some recent production. I have had issues after mods- often not the modification itself (bad solder joints or whatever), but rather something wrong I did in reassembly, or some bit of gunk that got into the motor or gears while I had it apart. 

[djconway]

Both of the GP35's I purchased were very slow on DC, but I tossed my old DC power packs back in 1995 when I switched to DCC.  So i was only able to test with a wall wort DC source. I know now that that was a bad idea, but these two locos are the first Atlas locos I've had issues with, Other than connectivity. I really don't like the bent tab board to motor connections.

I may switch it back to DC and see if I can dig up a power pack.  With the Amherst RR show coming up in a few weeks I should be able to pick a fairly good DC power pack.

With well over 100 Atlas locos (mine and friends) converted to DCC science 1995 I'm usually fairly good at finding and fixing any issues that arise from installation errors.

[peteski]

A 9V battery makes a very handy pure-DC power source for testing locos. Yes, it is one-speed only but that is usually enough for a test.

I was hoping to see the the test with the shell-less chassis to see if the motor heats up and a full tear-down results. But I guess you have other ideas.

[AKNscale]

A 9V battery is an excellent suggestion and exactly how I diagnosed the bad motor in mine

[peteski]

A 9V battery is an excellent suggestion and exactly how I diagnosed the bad motor in mine

Yup - it is one of those indispensable (and very cheap) tools in my took kit. I even take one to the trains shows for a quick trackless test of a loco I might be buying.  The only snag is that while it usually gets the sound going on DCC sound locos, 9V is usually not enough for the motor to start running. But it is a good indication that the model is good. But it works great for DC locos.

[Nick Lorusso]

#1 question is did you test them on DC first?

[djconway]

I have a 6vDC wall wort that I usually test with. Both locos ran very slow.  But one now runs ok after 6 - 7hrs of run in with the decoder installed.  The other is a different story still running slow after 6 hrs. 

After almost 200 Atlas loco installs these two are the first that I have any, significant problems.
Atlas' history has lulled me into o bit of complacency.

Going to have to add a DC circuit to my test track.

I will resolve the issue(s?) It may take a little effort this tkme.   

[GP40X]

I kept my Kato power pack from my M1 set to test on DC before installing DCC.  Did you ever do a tear down of the one that is still running slow?

[djconway]

Yes I have it torn down now,  ran into a bit of a problem while testing the motor.  Clamped the allagator clips to the brush caps, then somehow twisted the motor.  Found the brush but the spring is now in the ozone.  Going to pick up replacement springs & brushes at the Amherst RR show next weekend.  Failing to find replacements I will order a replacement motor from Atlas.

[peteski]

Yes I have it torn down now,  ran into a bit of a problem while testing the motor.  Clamped the allagator clips to the brush caps, then somehow twisted the motor.  Found the brush but the spring is now in the ozone.  Going to pick up replacement springs & brushes at the Amherst RR show next weekend.  Failing to find replacements I will order a replacement motor from Atlas.

If atlas does not sell replacement brushes/springs, Kato does.  Check their website.  They should fit Atlas motors.
I'm surprised that this happened to you - the brush holders are usually firmly inserted into the plastic motor frame.

[djconway]

  :facepalm:You would think that after 45 years in N scale I would know better.

[peteski]

:facepalm:You would think that after 45 years in N scale I would know better.

45 years in N scale? Then I would use "having a senior-moment" as a perfect excuse.  Hey, that's what online forums are for: to remind you of things you should have remembered. 

[Joetrain59]

Replacement motor from Atlas? HA! I ordered one for the pesky C420 I have, and the motor sent was tighter than a snail in a shell. $39 to boot. Sent it back, they should have it Monday, the 22nd.
 Joe D

[peteski]

Replacement motor from Atlas? HA! I ordered one for the pesky C420 I have, and the motor sent was tighter than a snail in a shell. $39 to boot. Sent it back, they should have it Monday, the 22nd.
 Joe D

Hmm . . . it seems that Atlas has started having some problems with their motors in the last couple of years. I've been dealing with Atlas locos (with "Kato clone" motors) since they started using them, and up until couple of years ago I have never encountered those motors where the armature was binding. And now this is like the 5th or 6th one I have been made aware of.

[Joetrain59]

Got the replacement motor today. Hand written on plastic bag, "motor OK". And it is. Spins much more freely by hand, and starts at much lower VDC.
 Thank you Atlas.
 Joe D