# DCC concerns



## New Berlin RR (Feb 11, 2012)

Ok I just got one of my cheap locos fitted with DCC, and before anyone says any thing about "spending more on the DCC then the locos are worth" please leave that out of the thread  anyways I got the Queen Elizabeth fitted with a DN163 (thats what the paper says) how ever when running it on my DC set up (least until I get my DC controler) it behaves a bit erraticially, when its set up with factory settings and values it runs fine, like a bat out of heck.

how ever when I try to adjust the speed curve to limit the unit to a specific speed cap it behaves a bit erraticially, mainly seems to be jerky. im trying to set the engine to cap at speed step 128 at 100 (im assumeing its scale MPH) for some what of a proto realistic top speed.



anyways what im trying to figure out is how can I do this, I am using JMRI so when I set the speed table up I use one of the graduating curves (I forget which button name it is but its like the first or second to the far left) and then write the values to the decoder, and then when testing on the layout it acts like it wants to die, also when I ran it flat out (with the configured speed steps to cap at a realistic top speed) it started real slow like I wanted then it just stopped tripped my DC circuit breaker then after it reset (the breaker) the engine was re tried at full it did the same except the second time it slowly started, stopped then two seconds later shot off like a bat out of heck again.


so I am wondering whats going on here, do I have a problematic decoder or is something else going on? the decoder that is being used is rated for the motor type in the engine so it should be working with out issues there, I have no lighting at all on this loco and I just needed basic control of the loco in question.


Thanks for the help!


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## NIMT (Jan 6, 2011)

Simple answer, You will not get good or accurate control of a DCC decoder on DC, they are not ment to be run like that!
Erratic operation can also mean that you have something wired wrong. If it is wrong or your shorting out the decoder, it's life span will be greatly diminished!


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## New Berlin RR (Feb 11, 2012)

ok thats kinda what I figured so I will be talking to the place that did the install to double check, as for the decoder is it possible to set the speed table to a more realistic top speed?? if so do the numbers on each speed step read in scale MPH or are they not a factor (as in are they there for something different??) as I want to set it up with realistic (for steam in general) top speed that a prototypical steam engine like this may have...as for DCC we did test on a DCC layout and it ran absolutly 100% perfict so I figure its just my DC controler thats acting up...


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## NIMT (Jan 6, 2011)

Using DC to control a DCC decoder is like trying to play an old atari came on your new state of the art PC. It works but with unknown results!

The numbers in the speed table have nothing to do with MPH they are a division of numbers from 0 to 255 (power factors), a setting of 100 is about 1/3 of the possible power being sent through to the motor, way too low a number! That's not where you set the speed limit anyway, it's done here.


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## New Berlin RR (Feb 11, 2012)

ah ok, cool, thanks NIMT didn't relize that!! thanks for the info tho!! I had a feeling that wasn't the right area anyways, will look at that section when I get home  

just to ensure im understanting it correctly NIMT the speed steps should be left to default values (the speed table(s))??


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## NIMT (Jan 6, 2011)

No the speed steps should be tweeked to allow for proper proto typical movement of the enines, Start slow and build up steam as it gets moving.


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