# DCC Speed



## bluejayeng (Jan 15, 2008)

Hi all you Hoggers. I am perplexed. I run USA trains SD70s, SD40-2s, and Aristo Dash-9s in MU combinations. All with Digitrax 583 style decoders. All have DSX sound. I have a DC50 Digitrax Zephyr command station and an MRC 8 amp PowerStation booster. This stuff runs slow. The layout has about 8 feeders distributed. No district separation (yet). I then switched to an NCE Pro 110A 10 amp booster. Nada. Same slow speed. The NCE booster voltage pot is fully turned for 20 (20.3) volts or just plain max. Mostly flat layout. Does anyone think the Zephyr may be the culprit? I tried adjusting CVs for max speed. No effect. I am wondering what's next. Any suggestions would be great. Thanks.


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## Chucks_Trains (Jan 2, 2008)

Hmm, boy I'd sure think that this booster would get your engines up to speed as it puts 24 volts on the rails...

Zimo High Performance Base Station (16A)


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## Greg Elmassian (Jan 3, 2008)

1. Have you actually computed the scale speed? You might be surprised. 
2. Have you measured the voltage on the track with a true RMS meter? 
3. There is a "trick" to turning up the voltage to max on the NCE, and you need to take the cover off and read this: 
http://www.elmassian.com/trains-mainmenu-27/dcc-battery-rc-electronics-mainmenu-225/dcc-mainmenu-29/specific-manufacturers/nce-equipment-mainmenu-30 under tips is a very specific explanation of how to adjust the voltage pot.
4. Realize that at even 20 volts on the track, your DCC decoders may drop up to 3 volts to the motor, so you could be getting 17 volts to your motor. Compared to 24 volts that most DC packs are capable of, this will explain why your locos are slower.

I put 24 volts to my rails, which gives about 21-22 volts to the motors. Even then, I have some passenger locos that cannot achieve prototype top speeds. Read my site about how top speed is generated in the last few volts to the motor.


Regards, Greg


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## Road Foreman (Jan 2, 2008)

What power supply are you using to drive the NCE booster.. It needs to be capable of 22 to 24 volts @ 12 amps or more.. This will prevent voltage sag to the booster.. To get 24 volts you will have to pull a Greg & send the booster to NCE for a tweak.. The Zephyr is doing it's job, acting as the command station.. Hope this helps.. 

BulletBob


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## Greg Elmassian (Jan 3, 2008)

Getting answers to 1,2, and 3 will probably reveal the problem. Blue Jay, any progress? 

Regards, Greg


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## bluejayeng (Jan 15, 2008)

Thanks for responding everyone. Well here we are:

1.) The measured scale speed is 38 mph with my friends scale car.
2.) The track voltage with an RMS meter is 15.8 volts. 
3.) I will contact NCE about providing me with a tweak.

Now, it is important to note that I have that PB1018 transformer attached as the source power to the Pro 110 booster (that was Bob's question). This poor thing limits the input voltage to 18volts ac and almost 10 amps. It runs quite warm. 
I have taken Gregs' advice and purchased the same supply he has. I have the same conditions as Greg - multiple trains, MU up to three, sometimes a DPU on the end of the train.

Thanks for all your advice folks. I will update when the new equipment shows up.

Thanks again.

Leon (Bluejay)


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## Greg Elmassian (Jan 3, 2008)

Good deal Leon, everything is clear now. So you are going for the 27 volt supply? Good, I did experiment to verify the input vs output. I only researched DC extensively, since AC supplies always sag, since they are unregulated. I typically "lost" 3 volts from the input to the output on the NCE booster. 

Be sure to try turning up the voltage pot as I described, it's almost impossible to do with a screwdriver from outside the unit, often you damage the trimpot. 

Regards, Greg


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## NMTrain (Feb 4, 2012)

I once asked this question of Digitrax, I'm use DG583's for the most part. In factory defaults, they have turned on their "suspersonic and back emf" features. To turn it off set CV57 to 6 and CV9 to 255. It adds about 10% (on average) to speed, you will notice a bit more motor noise.


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## Dan Pierce (Jan 2, 2008)

Does the decoder have a CV for controlling motor voltage? For Zimo it is CV 57.
And how about CV 5 for Vhigh? 
Either of these can limit the speed of an engine.


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