Rokuhan controller with Microtrains SD-40

Cactus Jul 28, 2019

  1. bostonjim

    bostonjim TrainBoard Member

    Thanks for throwing this out here, Cactus. Who knew? Jim
  2. husafreak

    husafreak TrainBoard Member

    Thank you SJ Z-man! Great link to related thread. A solution (besides switching to another brand of controller) may be possible. I imagine Z track center and other importers/dealers of Rokuhan controllers would be very interested in a solution as well and as seen in the release of the “Shorty wire”.
    Here is the response I got from Rokuhan, food for thought, the thought that we may have to do this ourselves ;)

    Dear Mr. Eric Schellenberger

    Thanks for your reply.

    1.Shorty motor car no stop with RC03/RC02 at throttle dial position Min.
    This is unexpected result.
    We released RC02 on 2011 and RC03 on 2013 based on existing loco spec.
    We have no plan to release shorty series at that time.

    Shorty has light weight and used same motor unit with existing Z gauge motor cars.
    As result, Shorty can be run less electrical current than ordinal Z gauge locos.
    And we found some shorty motor chassis doesn't stop at throttle dial position Min.
    of RC03/RC02 because of less current consumption.
    Therefore we suggest to fix direction switch on center if shorty no stop at Min position.
    And we have RC004 controller for shorty.
    Sorry for your inconvenience matter and please understand.

    2. New Marklin loco no stop at Min potion.
    3. Oval track get power only from RC03

    We understand your new Marklin loco doesn't stop at Min. position of RC02/RC03.
    However do you have same problem with existing old Marklin controller or not ?
    Frankly talk, ROKUHAN controller are designed based on ROKUHAN locos.
    And we fixed controller spec. as ROKUHAN locos get best performance.
    We are not sure new Marklin loco motor spec. and others.
    However we can understand new Maklin loco motor has good performance
    and required less electrical current.
    But we can't have responsibility for RC02/RC03 function with new Marklin loco.
    Please understand our position.

    So we can send only above reply at this moment.
    Please understand and let us know if you have unclear matter.

    Best Regards
    ROKUHAN support
  3. Garth-H

    Garth-H TrainBoard Supporter

    My experience with this controller yes supply in is 12vdc and the voltage regulator output is 10vdc and rheostat controls that from 0 to 10vdc when I had this problem the problem was in the regulator, check voltage across the two accessory snap terminals on the side if that voltage is not 10vdc the regulator is not working to pot can't control down to ) volts, in my case I found a cold solder joint on one resistor once fixed we were back in business
  4. Cactus

    Cactus TrainBoard Member

    Thank you. I will have a look at it.
  5. southernnscale

    southernnscale TrainBoard Supporter

  6. Cactus

    Cactus TrainBoard Member

    The snap terminals show 12vdc. I opened the unit, and must say that I am appalled by the shoddy-looking construction. Here's a photo of the board. I suppose that's dried flux all over it. Did you have to check all the resistors for an open one? These solder joints all look bad.
  7. rvn2001

    rvn2001 TrainBoard Member

    Just run it through your re-flow oven and everything will be fine.... lol
  8. Cactus

    Cactus TrainBoard Member

    Works for me! ;)
  9. Point353

    Point353 TrainBoard Member

    Looks like the sort of result that can occur when plain tap water is used to rinse off a "no-clean" type soldering flux.
  10. husafreak

    husafreak TrainBoard Member

    I honestly don't think there is anything wrong with your controller. Some of the new high efficiency motors just run on the minimum output required for the Rokuhan constant lighting. The stains on your board are unusual though. Mine that i opened did not have that.
  11. Cactus

    Cactus TrainBoard Member

    Interestingly, mine has stopped the behavior it had. Now, it shows 12vdc everywhere. The throttle no longer has any effect. Just power the thing up, choose a direction and the locomotive flies forward or reverse at top speed. There's no speed control at all. :(

    BTW- that change happened before I opened the unit to take that photo of the board. Luckily, I'll be moving to DCC next week (boards are on order), so the Rokuhan throttle will be used only to control turnouts. I'm still curious about it, and will probably poke around inside a bit to see what makes it tick (and fail).
  12. husafreak

    husafreak TrainBoard Member

    I retract my previous statement!

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