Discussion in 'DCC & Electronics' started by colin, Mar 11, 2006.

  1. colin

    colin New Member

    Good Day;

    I'm trying to run 2 locos together, and one wants to run faster than the other. I have changed the SV but I still can't get them to run at the same speed. Any suggestions?

  2. KirkV

    KirkV New Member

    Most DCC loco decoders have several CV settings to adjust actual motor speed for a given throttle setting. You might want to look in the docs for your particular decoder(s). Also, some throttles, such as the Digitrax Zephyr default to a 28 step speed setting when consisting with the throttle. Just a couple of ideas. Good luck.

  3. Len Marinaccio

    Len Marinaccio New Member

    Presuming that your controller & decoder are following the NMRA guidelines, I can think of three approaches:

    1. Look into speed restriction. This is a function of the controller as it sends a packet to your fast loco to limit its top speed. If either the controller or the decoder do not support this, you're out of luck, and truth be told, I don't know how the acceleration curve will be affected.

    2. You could try changing CV #5 if your decoder supports it. This specifies the "maximum power" to give the motor. 255 is full power, all the way down to 2 (which would be roughly 1% power so I doubt you would ever go that low). 0 or 1 should disable this speed limitation. Be aware that if you do change this value, you should also change CV #6 to represent your mid-range power, otherwise you could get a very strange acceleration curve. I don't like option #2 very much as it could involve a lot of fooling around if you have many locos and want to restore them back to normal operation later.

    3. If your decoder supports alternate speed tables (CV#67-94) you could build one for your consist configuration then switch to it when using the loco in a consist. I *like* this option but I have no idea how many decoders support the alternate speed tables.

  4. Harold Cole

    Harold Cole Member

    Start out with cv02 and see what it is set at,this is start voltage.Start with the first engine and find out what notch you want to start at.This is done with cv02 and most everyone will start with cv02 at about 38,if this is good for you set the next engine the same.If the second engine doesn't start the same as the first set the second engine about 3 numbers higher until you have them starting together.Next set cv06 on first engine to 128 which is half speed,set second engine the same cv06 to 128,if second engine is slower than the first reset cv06 at 3 numbers higher till you have them the same.Last but not least cv05 is top speed,set first engine cv05 to 255 and do the same with second engine.If second engine is slower than set first engine down in numbers on cv05 till you have them matched.This takes some time.You can also set the speed tables but i wouldn't advise it till you have fooled around with cv02,06,and 05,these 3 cv's will get the result you want.Each decoder has a manual for speed steps,there are not many that don't support this option.Setting your speed steps are a long and drawn-out way of setting the decoders,but is a very neat feature.Hope this is of some help and good luck. Harold
  5. Harold Cole

    Harold Cole Member

    By the way what system are you using¿
  6. colin

    colin New Member

    Hi Harold;
    I am using the Prodigy Advance system; with some MRC sound decoders and some Digitrax decoders.

    Regards Colin
  7. Harold Cole

    Harold Cole Member

    Colin you should be able to match the speeds as to my reply.Mrc and Digitrax decoders respond very well to speed matching,i've had real good luck with both and also with them combined. Harold

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