• N Cliffe

    An interesting conversion.
    I did one some year ago, having found the original decoder in the Kof to give quite poor running. I used a CT DCX74 or DCX75 (can’t remember which, and conversion was for someone else).
    Whilst there is a concern over the low voltage motor, in practise motors are usually killed by stalling (too much current) rather than too many volts, unless those volts are really excessive. I’ve been running lower voltage motors on both standard 12v DC and DCC for a long time (decades on DC!), as have other modellers in the UK, and the motors do not seem to suffer. So, if the track current is reasonable, say under 16v, things should be fine without a special decoder.
    The installation of the CT needed some extra resistors for the lights. I used a couple of surface mount resistors on the ends of leads from the decoder.
    With the CT, the Kof performed wonderfully. Its bottom speed was imperceptibly slow, taking over a minute to move 4cm.
    Adding the capacitors is a good idea in small four wheeled locos, I’ve been doing that in other small locos recently.

    • Thanks for the comment, it’s good to know those little motors may not burn with regular decoders!

      I’m not an electronic expert really, I just know the DH06A has a voltage dropdown mechanism of some kind (not an usual feature on DCC decoders)… so I went for the safest option (plus the onboard driver cab LEDs were nice).
      A DCX74 or 75? You’re a real pro 😉 That’s a lot of soldering in a very small space. My solution, admittedly, is lazier: the pins of new DH06A matched the ones from the factory decoder 1:1 …and both decoders are actually bigger than a DCX!

  • MesmeroJoe

    I’m almost tempted to upgrade mine (I don’t need to explain why, clearly!). I’m not sure if I’m quite ready to jump into micro-soldering tiny bits just yet though….

    • Can’t decide for you 😉 My thoughts…
      Problem with DIYing is always the fear of damaging the precious locomotive (a $30 decoder, you can always buy again….).
      This Köf thing is actually easier than most decoder installs, since you basically open the roof, unsolder the wires, carefully noticing which wire goes where, and then simply solder the wires at the same place on the new decoder. Adding caps is more advanced, but you actually do that BEFORE inserting the decoder in the engine. If you’re careful and don’t use a too hot iron (don’t damage too much of the wires plastic isolation layer!), it’s feasible.
      The higher risk though, as opposed to other decoder installs, is damaging the wires (e.g. melting too much wire isolation). Having to replace one wire (all the way to the motor or a LED) in this tightly packed locomotive surely would be a hassle.

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