Kato F7A no longer working.

Vaccam Jun 12, 2013

  1. Vaccam

    Vaccam TrainBoard Member

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    Hello all,

    My LHS just told me I have a defective motor in my Kato F7A. Does anyone have any step by step instructions on testing and replacing one of these motors? Kato sells them for $26, so this looks like a DIY to me.

    Thanks for any info,

    Michael
     
  2. John Moore

    John Moore TrainBoard Supporter

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    Before I would write off the motor I would remove same and examine carefully for any foreign object that may have made its way into the motor jamming up the works. Then I would apply the old 9 volt battery test to see if it works. If it does the problem is in the mechanism or pick-ups and not the motor. Now I have never had to take any of mine apart that far so for instructions on how to get the motor out with the least hassle I would have to rely on someone here who has done it. Although I would hazard a guess with a split frame assembly one would just have to take apart the frame halves.
     
  3. Vaccam

    Vaccam TrainBoard Member

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    Thanks John! I read in an older post that even paper inside the motor would cause it not to run. I have been installing feeders and there are some small pink fragments here and there, so I am hoping that I will find something like that causing the problem. The engine is several years old, but barely used. I have heard that the Kato engines are very reliable, so I am hopeful. There is was no odor when it stopped, it just would not go either direction anymore. I swapped the DCC encoder out to another engine and it worked fine.

    Hopefully someone else will chime in with some directions.

    Thanks again,

    Michael
     
  4. EMD F7A

    EMD F7A TrainBoard Member

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    I see that you have a decoder-equipped F7, so I assume it's the new version. I say while you've got the decoder out, apply power from a 9v battery straight to those motor contacts. Then you'll know whether it's actually the motor, and go from there! (Even if it's a bind in the gears, the motor will wiggle/buzz when power applied)
     
  5. Vaccam

    Vaccam TrainBoard Member

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    Thanks EMD! Yes it is a new version.

    I was able to figure out how to disassemble the engine. It is pretty easy actually. After removing the shell, you remove the encoder and the two contact strips, being mindful of how they are installed. Then you can pry-off both worm gear covers. You then pry-off the motor mount by using a small screwdriver along the seam and then just wiggle it off. You need to be careful to see were everything goes during disassembly. When you pry-off the motor mount the motor will come with it and the worm gears will fall out. Everything is very easy to put back together, just do the reverse. If you remove the motor from the motor mount you need to becareful when re-inserting the motor, or you can bend the motor contacts.

    Please attempt this at your own risk. This is not meant to be a detail instruction list.

    Does anyone know if the worm gears are identical? Is there a front and back?

    I must say I was very disappointed in my LHS. They told me my motor was bad, which indeed I think it was, (I applied 9v and just a tiny whine), but they for some reason decided to solder the motor contacts to the main contacts and proceeded to melt the plastic below. If they tested the motor and found it was bad why did they need to solder the motor contacts to the main contacts.


    Check out this sad picture.

    securedownload3.jpg

    Thanks for looking,

    Michael
     
  6. EMD F7A

    EMD F7A TrainBoard Member

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    That's a darn shame. I wouldn' take anything back to them to.... "fix".
     
  7. randgust

    randgust TrainBoard Member

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    Wow.... OK, so welcome to the wonderful world of 'well, I may not know what I'm doing but I certainly can't do any worse than that!'. That's kind of how I got started in this.

    Consider this an opportunity. If you can take pictures like that, and hang in there, I think this crew can get you through it for tech support. And you're well on your way yourself here.

    So, you've established that the decoder works in a different locomotive, correct?

    But did the motor actually function or not? 'tiny whine' doesn't really say if it's spinning up right or not.

    Kato does stock the replacement motors and they have everything online. See
    http://search.cartserver.com/search...C&maxhits=100&go=List+Parts&bool=AND&bool=AND
    this is probably the replacement motor you need:
    http://www.katousa.com/images/926090.jpg
    You're going to have to undo that awful soldering job though with some solder braid or something. Sure won't work that way on a DCC layout. Not sure if there's any real damage beyond the motor or not.

    I find it very helpful to make up a 2-wire jumper cable set with subminiature alligator clips soldered on it (Radio Shack has those by the bag). For conventional 12V testing you can clip leads to the track, then clip the other end to various contacts and frame parts, or even clip straight pins into them to use as powered probes to reach around without complete disassembly. REALLY useful for stalled locomotives to try to find out even which wheel isn't picking up right.

    Consider yourself fortunate that you're dealing with a Kato. N scale parts for online purchase can sometimes be next to impossible to find; different manufacturers do a far different job on this end with Atlas the best, Kato good, Bachmann hanging in there a bit, and the most of the rest a matter of luck and phone calls.

    I've concluded that even if the manufacturer doesn't say the parts aren't interchangeable, I scratch ID marks on almost every part as to assembly orientation, 'F" and "R" and arrows on trucks, a tiny number on the TOP of each bearing block as to which one came from where, and a mark on the universals as to front and rear. I had a lot less grief with reassembly when I started this process as even things as seemingly insignificant as bearing block orientation seem to contribute to otherwise inexplicable noise problems on reassembly.
     
    Last edited by a moderator: Jun 13, 2013
  8. Kevin M

    Kevin M TrainBoard Member

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    Looks like they screwed up your engine. Not only do you need a new mother but I would replace the contacts and plastic piece. I would try and get them to replace that stuff or get you a new engine.
    Kevin
     
  9. Vaccam

    Vaccam TrainBoard Member

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    Thanks for the info Rand! That was my plan, to get the parts from Kato and rebuild it. I had seen that most of the parts were available. I also found the motor mount which does not appear to be available from Kato. So my plan is to get the motor mount now and the contact strips and motor from Kato next month.

    You are right it is a great learning experience. I had originally opened up the engine and tried to figure out how to get to the motor, but thought it was more difficult that it is. I searched on-line for instructions and couldn't find any. I then found instructions on Kato's site to disassemble the GG1. They mostly say pry-off this or that part off, so I figured the same might be true for the F7s, and it is.

    So, I have completely disassemble, cleaned up and reassembled the little engine. Here it is now, still doesn't run but it does not look quite so pitiful.

    Thanks,

    Michael
     

    Attached Files:

  10. Vaccam

    Vaccam TrainBoard Member

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    Yeah, Kevin, they sure did. I will send them the bill.

    I've never liked this LHS very much. He is a nice enough guy, and originaly from Pittsburg my home town, but doesn't stock any N scale items anymore. He says he can order anything I need, but so can I. I thought I could at least use them for scenery supplies, but now I will probably stay away. It is a shame, maybe I am the only n scaler he sees. I miss being able to pop in a store for an item I might need, or sometimes an item I don't need. :)

    Thanks,

    Michael
     
  11. randgust

    randgust TrainBoard Member

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    If you don't already have one (being a DCC guy) get yourself a cheap used 12v power pack for testing purposes. Any train set type will do (including HO), all you want to be able to do is produce about half an amp of DC power. I have a little test board I set up with 24" of track, a second reversing switch, and the jumper wire clips as a test bed. Batteries work but you'll chew them up rapidly, and they don't produce enough current to really kick over a stubborn mechanism.

    It's really rare to get a burned out Kato motor. They tend to run long and cool with very little attention. Even with ham-handed service, unless they actually damaged something on it I'm finding it difficult to believe the motor itself is damaged UNLESS soldering the leads to the pickups and putting it on a higher-voltage DCC feed cooked something around the commutator. Could have, but still unlikely.

    One of the things you should do if you haven't already is just drop the trucks out of the thing (loosen the frame sides enough so you can get them out, then tighten them back up) and try it again under DC power direct to the motor leads. You want to prove there isn't something in the trucks binding it up. You can also roll the trucks around with your fingers on the track to make sure there isn't something stuck in there. They should roll very smoothly.
     
  12. Hytec

    Hytec TrainBoard Member

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    Also consider a piece of ballast or similar chunk of something stuck between two teeth in the gear train. It will be hard to see if there is any amount of grease in the gear train. I use a magnifying lens and dental pick to check between each tooth pair until I find whatever it is. If I find nothing, I look elsewhere for what's jamming the motor, including something jammed between the armature and a magnet pole.

    Like Randgust says, Kato motors are nearly foolproof, though occasionally nature does invent a more talented fool...LOL
     
  13. Vaccam

    Vaccam TrainBoard Member

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    Rand and Hank, thanks for the suggestions. I will give them a try. I don't have any ballast yet on the track, so It won't be ballast. I am sure it can be something else so I will take a closer look. I did move the wheels while the motor and worm gears were removed and the gears seamed to move smoothly. I don't have a dc power supply, but tried connecting a 9 volt battery to the contacts on the side of the motor while it was out of the housing. It just whines softly with no movement at all. Is this a valid test? Is there another way to test with the motor out of the housing? I think I may have a power supply in an American Flyer set I have in storage. I will see if I can dig it out this weekend.

    I have not figured out how to get the trucks out yet. I removed the silver plastic sides and the cooper strips between the plastic sides and the wheels. Will the trucks just come off if I give them a good tug? I try this but was afraid I might break them.


    Thanks again!

    Michael
     
  14. Hytec

    Hytec TrainBoard Member

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    Michael, if each gear train can rotate freely when you rotate the wheels more than 360 degrees, then there probably is no blockage in the gear train. If you can rotate the motor and worms freely by more than 360 degrees, then you probably have an electrical problem. A "whine" has me puzzled, though that could indicate a shorted commutator or armature winding. A fresh 9V battery should have enough amperage available to spin the armature under normal conditions, because modern motors should spin drawing less than 10 milliamps with no load like a gear train. If the motor does not spin with a fresh battery, even if you give it a spin in both directions with the battery connected, then the motor probably is damaged in some way.
     
  15. randgust

    randgust TrainBoard Member

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    The trucks basically clip in, they are held by the frame halves. You really should loosen the frame halves before you jerk too hard, but they are designed as a clip method into the metal frame halves. See the picture. Standard Kato design, except for the really long pickup ears.

    http://www.katousa.com/images/929301.jpg

    You don't disassemble the trucks at all, you just loosen the screws on the frame itself. That's pretty much standard on any metal split-frame diesel mechanism in N scale.
     
  16. Vaccam

    Vaccam TrainBoard Member

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    Just prior to the engine not running I had several derailments through a #4 turnout that was giving me porblems. Maybe it caused a short, but I would think the decoder would go before the motor.

    Ah! I did not realize there was a metal split-frame. I will take a closer look.

    Thanks Guys! I will let you know what I find.

    Michael
     
  17. Bob Horn

    Bob Horn TrainBoard Member

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    Michael, it is not a split frame. The trucks clip over the side of the chassis under the grey covers. Remove the covers and use a small screwdriver to pop the clips over the mount. Go to the Kato site and pull up the maintence for the F-7, F-3 or E-8. They all attach the same way. Bob.
     
  18. Vaccam

    Vaccam TrainBoard Member

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    Thanks for the update Bob. I haven't been able to find disasembly instructions for any of these engines on Kato's site. All I see are instructions for the coupling and a parts diagram. Am I looking in the wrong place?

    http://katousa.com/N/F7/maintenance.html

    Thanks,

    Michael
     
  19. Hytec

    Hytec TrainBoard Member

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    Don't know anything about DCC decoder design, but I suspect there are one or more self-protect circuits on the board. Basically they sense an overcurrent (short) and route the current around delicate decoder circuits, assuming more robust components, the motor in your case, can survive a transient overcurrent. Maybe yes, maybe no...?

    If you have an ohmmeter, the resistance measured between the two power tabs should be greater than 100 Ohms, possibly nearer to 1000 depending on motor design. Also, the meter should fluctuate slightly when you turn to shaft slowly as the commutator rotates under the brushes.
     
  20. Bob Horn

    Bob Horn TrainBoard Member

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    You are in the right place. The parts diagram shows what the parts look like, as i said the grey parts which hold the contact strips over the trucks need to come off to access the truck clips. Bob. Once you take apart it is very easy to understand.
     

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