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Thread: Kato SD70 encountering dead spots

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    Default Kato SD70 encountering dead spots

    Hoping smarter people than me can help me with a baffling issue I'm having with my Kato SD70ACe:
    When the engine hits certain parts of my layout it momentarily will stop and then start going again a second later.

    At first I thought the track was dirty so I cleaned those spots. However, of my 4 locomotives the SD70 is the only one having this issue. The other 3 roll through with no drop in speed. This tells me the problem is most likely with the locomotive and not the track. I cleaned the wheels using the Woodland Scenics Roto Wheel cleaner and that really didn't seem to make any difference. Is there a better way to clean the wheels? Could it be an issue with the Digitrax decoder?

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    the problem may be further into the mechanism.
    some one here recently fixed a pickup issue by adding a second set of chassis strips.
    kind of unusual...

    more common is lint in the axle pick-up points.

    cleaning the loco is the next step.

    victor

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    Quote Originally Posted by SeattleSUP View Post
    When the engine hits certain parts of my layout it momentarily will stop and then start going again a second later.
    Does this imply that it stops in the same places or is it random ? Dcc ?
    Thanks, Tom

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    Yes, it's always in the same couple of spots which is why I initially thought it was the track. Cleaning and even changing out pieces of unitrack did eliminate one spot. Also one of the spots is on a piece of Kato power feeder track. My system is DCC, specifically a Rocco z21 unit. The layout is pretty small - 8 feet by 2 feet - with two outer loops, a smaller inner loop and a 4 track yard. The part that I find baffling is that if it was some sort of contamination - say a piece of lint - in the gears of the locomotive this would cause issues all over the track rather than at just a couple of very specific spots.

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    fun stuff ain't it?

    the track has been cleaned... that means clean loco ...

    to answer your question why just this one spot.

    If you have a truck just one full of lint in the pick-up cups
    (that truck is not giving any pick-up) and the other truck has two wheels that do pick-up.

    you track is excellent and only has one place where just one wheel can't quite touch the rail
    and ding! a stall. plastic frogs can do much the same.

    you happen to have a spot here your pickups that work get off the rails.

    victor

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    Check the wheel gauge of the loco and then the track gauge at those spots.

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    Let me ask this , could it be a lack of track power ? It would seem to me , that if its always in the same spots , its a track issue . Check that you have full power to the track in those spots . Is there a feeder near or at those spots ? Gently clean the inside of the rail there not just the top of the rail . Others may be right , that its the loco , but i suspect its a track issue losing power , or enough power that the loco stalls

    Steve

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    One of the spots is on a section of Kato feeder track so that seems unlikely. I forget the total power that the z21 system puts out but I do know they power much bigger layouts than mine. I also have feeders going to each of the three loops.

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    OK, that would make the most sense and explain why it's in a particular spot and with just one locomotive. One of the dead spots is just after the locomotive starts up a grade so I'm guessing that one truck being on the grade and the other being on level ground might be causing an oh-so-minute loss of contact.

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    Quote Originally Posted by victor miranda View Post

    more common is lint in the axle pick-up points.

    I second this motion; always the culprit when you have intermittent pickup issues like this.

    Metro Red Ln (Metro Red Line)
    Under the streets of Los Angeles

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    Kato feeder track sections , are notorious for failing . If you ever have the chance , remove the bottom and have a look at how the power gets to the track . Its through 2 pieces of stiff wire , that touchs the bottom of the track . It has a contact point of less than 1mm . If this should corrode or get oxidation or have a bad contact from micro arcing , they will fail . Of Kato's system of transferring power to the track , this is the weakest link by far . I have personally seen them fail . The unitrack joiners have a far better contact point between the rail sections than the feeder track section does inside . Take a look at one inside , you may be surprised by what you see .

    Steve

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    Quote Originally Posted by MetroRedLn View Post
    I second this motion; always the culprit when you have intermittent pickup issues like this.
    Always in the same 2 spots on the track ? The problem always happens in the same spots on the track , i doubt the lint problem would just always happen at the same spots . But thats my opinion after reading his OP and further replies completely .

    Steve

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    Quote Originally Posted by SeattleSUP View Post
    OK, that would make the most sense and explain why it's in a particular spot and with just one locomotive. One of the dead spots is just after the locomotive starts up a grade so I'm guessing that one truck being on the grade and the other being on level ground might be causing an oh-so-minute loss of contact.
    This may be due to the transition of the grade , one of the trucks might momentarily lose contact with the brass strips the the trucks contact to pass on power to the frame . Grade transitions should be very gentle and never start at a track joint or very near one

    Steve

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    Could be pickups as well: try setting the locomotive on a level piece of track, with lights on. Gently pick up one truck so it is free of the track and the lights should stay on. Replace the truck on the track and try the other truck. If the feeder strips that connect chassis and truck are in place and working correctly, the locomotive lights should stay lit throughout the procedure. If, when lifting one truck, the lights go out you'll want to examine the brass feeder strips on the other end to ensure they are contacting the truck.

    After this step, move on to the lint cleaning solutions suggested by others... which you may want to do anyway. Basic preventative maintenance is a good thing.

    Sam

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    I think you have a wheel(s) leaving the railhead.
    Those long diesels are notorious for that.

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    Put the loco on a flat glass, and have a look if it's elastic when you press the whole loco down. If not is a issue with shock absorber in one or both truck's. If it's, disassemble both of them, check the condition and calibrate if need. Lubricate light with Conducta Lube or Silver Grease. Look like you have a mid axle not touching the rail in that spot. I think also you can have a slight bump or vertical kink in that place, and this loco only is sensitive and lose the power for a blink, until next wheel make good contact. I experience twice this trouble with long locomotive, at the start of ramp, in curved section on my diorama. This part are clearly pictured here by Spookshow:
    http://www.spookshow.net/loco/katosd70.html

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    This was the problem. I gently pried the chassis feeder strips out a tad as well as the connectors on the trucks and now it's running like new. I actually think this problem came about because I fixed a lint problem! I had some odd noises coming from the locomotive so I disassembled the trucks and found the offending piece of lint. I suspect that when I put the trucks back together I didn't get the contact tabs set properly.

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    .
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    +a bunch for the 10 char minimum

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