Atlas Nscale GP-38 Electrical glitch?

Discussion in 'FAQs' started by Herc Driver, May 25, 2008.

  1. Herc Driver

    Herc Driver Active Member

    Got a quick question guys that maybe someone with greater electrical understanding can answer. I have an Atlas GP38 unit that I was running on the new and yet unfinished layout and noticed that occasionally both the front and rear number boards were lit at the same time while the engine was moving forward down the rails. And to add to the problem, I'd only get both rear and front number boards to illuminate at certain sections of the track - not the entire layout. I cleaned the painted rails in the area where I first noticed this problem and actually think it helped. At first I thought maybe a power pack wire was touching the DC accessory screw and providing another source of DC power besides the track leads, but that wasn't the case. Then I wondered if I had mis-wired the three sets of feeder wires to the layout tracks, but that checked ok too. So I'm left with the diesel itself...this little guy has never sounded "right" when it ran on the previous layout and still doesn't sound like the motor runs well now on the new yet-unfinished layout. I removed the shell and can't find a stray wire or for all you Atlas diesel uber-electricians - could I get some ideas of what else to check? Is it possible (however improbable) that there's too much paint on the inside of the rail and current is being picked up just sporatically enough to "fool" the circuitry? Additional facts...this diesel has never ran well and sometimes the motor changes the way it sounds - going from what I'd call a normal nscale motor sound to a higher pitch sound. It's done this from day one out of the box. Also, I think this Atlas product is about 5 years old, not one of the more current motor/frames recently released.
  2. Biased turkey

    Biased turkey Active Member

    Herc Driver, I don't have experience with 5 years old Atlas engines, but the 1st thing I would try is to swap the trucks assemblies. On the new Atlas engines, you just have to pull gently on the truck assemblies to separate them from the frame.
    Note carefully the gears position before swapping,you don't want to have 1 truck pulling forward while the other is pulling backward .I 've been there, done that wall1

  3. Biased turkey

    Biased turkey Active Member

    By the way Herc, don't you think you'll have more chance to get more replies if you post that question on the N scale subforum ?

  4. Herc Driver

    Herc Driver Active Member

    Ya know - both your ideas are probably worth trying. Thank you very much! It's funny I didn't notice the "double lighting" until now. I don't think it's the track (electrically, I don't see how it could be) so it must be the motor/lighting wiring. Thanks again.
  5. Russ Bellinis

    Russ Bellinis Active Member

    As far as your motor changing pitch while constant running, it sounds like something is loose allowing something in the drive to bind up. It might also be a bit of "flash" on a gear in one of the gear boxes. If a complete disassembly and inspection under a magnifying glass doesn't reveal your problem to you, you might contact Atlas about the locomotive. You might be able to send it in and have them repair it for a small fee. If their warranty is like Bachmann's, after one year they will only require you pay the shipping cost to send it back to them and enclose a check to cover shipping it back to you.
  6. Herc Driver

    Herc Driver Active Member

    Thank you very much. I might fly airplanes, but the idea of tearing into an engine gives me the shivers. Still, sounds like that's what I'll have to do. I haven't seen or read about this kind of electrical pickup problem (both front and rear number boards getting power for an instant) so I'm still trying to figure the problem out. When I get back home, I'm gonig to tear into it and see what I can find.
  7. Russ Bellinis

    Russ Bellinis Active Member

    Before you tear into it too far, look closely to see what it uses for pick ups to transfer power from the wheels to the motor. I model in ho, so I have no clue about n-scale locomotives, but I suspect they use some sort of brass wiper on the back side of the wheels. Make sure you have good connections where they rub and you might also apply a bit of rubbing alcohol to the wipers and wheels where they make contact to make sure you have clean contacts.
  8. Biased turkey

    Biased turkey Active Member

    Russ suggestions make sense, but I'm still very puzzled with that "double lighting" problem. It sounds like a bad insulation problem.
    I'm a ( retired ) electronic technician, and I really would like to have a complete schematic of an N scale engine circuit.

  9. Herc Driver

    Herc Driver Active Member

    Cleaning the contacts will be first on my list. There are "pickup" strips that seem to be contacting and remaining in contact while the engine moves. For the power to momentarily take the path to the rear number board lights - without changing the direction of the motor from forward to reverse (or even slowing/sputtering/stopping suddenly) my initial guess is a bad wire picking up residual power off the metal frame...but that's only my guess. When I really tear into it - hopefully I'll be easily able to follow the wiring path from the wheel contacts to the motor to the lighting.

    I don't know lots about electricity when it comes to moving through an engine...but is there any way a bad track to wheel flange connection could allow the flowing electricity to cause this? I can't believe it would, since the electricity flowing doesn't make the motor reverse itself. So I'm left with bad wiring inside the shell going to the lighting.

    Again, thanks guys for the suggestions. When I get home - I'll put 'em to the test and see what's causing this problem.
  10. platypus1217

    platypus1217 Member

    Do you know if the GP-38 is supposed to have directional lighting?

    I am trying to understand if the light is on when it should be off (not enough insulation) or if it is off when it should be on (not enough connection). They are two different situation and might require two different solutions.
  11. Herc Driver

    Herc Driver Active Member

    The lighting is directional (but to be sure, I'll recheck the Atlas website regarding this engine).

    Funny thing is, the lights flicker or remain illuminated for a very short durations at predictable places around the layout which leads me to believe this all stems from a track issue. But since I have no reverse loops, no crazy electrical switching, nothing that should cause this, I can't figure out why this engine would be doing this. I throroughly cleaned the tracks, made sure the metal stip contacts are hitting the wheel sets correctly. I'll check the engine wiring as soon as I get back home, since that seems to be the only option left. My guess is there's an insulation problem and the rear number board wire is picking up stray voltage...but that's only a guess right now.

    Thanks very much for trying to think through this problem and offer suggestions/solutions though - I really appreciate it.
  12. Russ Bellinis

    Russ Bellinis Active Member

    Herc, are you relying on track joiners to carry electrical current? If you don't have drop wires soldered to each rail, that may be the source of your electrical problems. The rail joiners may be making poor electrical connections.
  13. seanm

    seanm Member

    If the power from the track drops out and the engne continues because of flywheel action could the back flow of current from the engine be seen by the light board as reversal of current? If so that would explain why the back boards light up for an instant. That might be the instant that the shaft is turning, but there is no pickup from the track.

    Dunno though, it is just a guess.
  14. Herc Driver

    Herc Driver Active Member're absolutely right about the rail joiners and I will solder the rails together and add drop wires. That's on the things to do list. For now, mostly to check for alignment problems and rough in the scenery, I have the track connected with rail joiners. This little engine has brought to light either a track issue or an internal electrical issue. And since I just made it home today, I'm going to try to find out which issue it is and fix it.

    Very interesting idea SeanM - thank you. I might try to run the engine without the shell to see what's going on and if you're theory is right.

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