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DH123AT fine tuning

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  • Member since
    June 2007
  • From: Rijeka, Croatia (Europe)
  • 192 posts
DH123AT fine tuning
Posted by Thommo on Friday, October 3, 2008 5:15 AM

Hello all!

I have installed DH123AT decoder in the HO Bachmann Shay loco. No problems there, I used 8-pin harness for the decoder.

But, as I run it, I noticed that decoder works in a strange manner. When I turn the control knob to FORW or REVERSE, loco starts a bit fast, like a little power surge is applied to the motor, and than goes smoothly through whole speed range, and also deccelerates with no surges. It seams the problem is only in the moment between idle and go.

I hope you will understand what is my problem. Anybody has some idea?

Thanks!

  • Member since
    June 2004
  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
  • 25,640 posts
Posted by jeffrey-wimberly on Friday, October 3, 2008 5:20 AM

Does it do this only when you go from forward to reverse? If so, that's being caused by slack in the gears. The motor turns with little or no resistance against ituntil the slack is taken up then it will hitch a little bit.

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  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Friday, October 3, 2008 11:52 AM

You may have CV 2, Start Volts, set too high.  Start with it on 0.

CV 3, Start Momentum, may need adjusting.  A higher value will result in slower startup.

Some decoders don't function well on DCC if CV 29 is set to allow dual mode operation.  Turn off DC operation by programming CV 29 with a value of 34 and see if that helps.

  • Member since
    June 2007
  • From: Rijeka, Croatia (Europe)
  • 192 posts
Posted by Thommo on Monday, October 6, 2008 6:49 AM
It was CV65, kickstart was ON. I put it on zero, now it's OK.

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