# locomotive runs extremely slow on dcc



## Dennis461 (Jan 5, 2018)

My Athearn blue box, brass flywheel runs extremely slow on dcc
JMRI , Arduino, laptop.
Decoder is a XL systems, generic (no model number) non-sound (I think) diesel decoder.
Brand new install, tried many different CV settings,including factory defaults.

My other installs are going OK (different decoders).

I know DCC is normally slower than DC for many reasons, but this one barely moves.
The engine was one of my favorites on DC.

My plan is to rip it back out and put a digitrax in there.


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## MichaelE (Mar 7, 2018)

Have you checked the CV for top end speed and the CV's for the speed table?


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## Dennis461 (Jan 5, 2018)

I revisited CV 5.
The literature which came with the decoder had a typo.
And I suspect, a wrong setting in the eprom for the default value.
I changed it to 255, loco speed is now reasonable


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## CTValleyRR (Jul 26, 2014)

Glad you got that figured out. It's always a good idea to remember that, for the most part, DCC should provide 0-14vDC to the motor, whereas some conventional power packs go as high as 16v. So maybe a minor speed difference at the top end. Unless your system is near it's peak amps already, the added gadgetry and sound won't affect speed.

That said, some decoders will (by design) limit motor voltage to less than what is being fed to the tracks, and certainly CV settings have a significant effect. It is not uncommon for factory settings to be way off. Whenever a loco takes a huge speed hit after converting to DCC, CV settings are almost always to blame.


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## D&J Railroad (Oct 4, 2013)

Switcher mode, i.e. F7 cuts down the top speed also.


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