# Oldie with DCC questions.



## Chops (Dec 6, 2018)

I dabbled with DCC back around 2005, and for the most part enjoyed it enormously, what with being able to run five trains on a single main line. 

I was using an MRC Command Control and MRC decoders. 

I got out of it, after a while, because I consistently had issues with the decoders getting stuck on full throttle, or whatever the last speed setting might have been. This would happen after about 45 minutes of continuous run time. I would polish the track with alcohol wipes, and then things would work again. 

My guess is that the low AC current was getting blocked by a thin layer of grime an oxidization that naturally occurs from micro arcing and sparking. Would this be correct, or am I completely wrong?

I still have my old DCC equipment boxed up, and am thinking about doing up some of my British OO stuff. Because I really like to keep things simple, I picked up a Bachmann Easy DCC power pack along the way, but haven't used it yet. 

To repeat a question, and sorry for sounding dumb, but this Bachmann should interchange with MRC decoders? 

Part of the reason I am asking is that if it's not a dirty track issue, then are MRC decoders prone to fail? :dunno:

Thank you in advance for your advice, suggestions.


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

The DCC power pack or whatever it's marketed as will work with any DCC decoder. The NMRA has established standards for the industry to comply with or at least come close to complying with. 
As for the MRC decoder, I've never had one that didn't give me problems after a short bit of running.
Decoders aren't expensive and can be replaced quite easily with the 9 pin connector. An basic Digitrax decoder will work just fine in the locomotive and should hold up to operating far beyond the 45 minutes.


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## DonR (Oct 18, 2012)

The MRC DCC controllers are on equal with Digitrax
and NEC. However, ever so many forum members
have expressed problems with their decoders. The
Bachmann EZ is easy to set up and is easy to use. It does lack any ability to fine tune decoders but some of us don't
need that capability.

I have never used MRC decoders. My locos have various
makes, Bachmann, Digitrax and NEC. All work fine
tho the Bachmann won't tune as fine as the others.

It is important to clean the rails and the loco wheels
often, the frequency depending on how protected your
layout is from dust and other contaminates. My layout
is in a 100 % climate controlled room. Even so, if
it sits idle for a week or so I run my track cleaning
car before any of the trains. 

Don


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## CTValleyRR (Jul 26, 2014)

I agree with Don. I have an MRC Prodigy wireless, and it's as good as anything out there, and far easier than some. Their decoders, though, have a bad reputation, and this seems to be borne out by your experience.

DCC isn't a fan of dirty track either, and you do have to keep your track clean. Brass is much more finicky in this respect than nickle-silver.

The Bachmann EZCommand is a fine unit, but it has limited functionality (you can't program decoders), and it is not expandable.


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## Chops (Dec 6, 2018)

Thank you, useful information. Based on that, I will scrap my few old MRC decoders as I am keen on reliable operation. That being said, the use of capacitors to "stay alive" is news to me. Can you recommend any such decoders?

Ideally, I'd like to run three trains simultaneously upon a four x eight layout. Would the AC voltage drop require adding in bus wires?


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## mesenteria (Oct 29, 2015)

There is more!! Decoders brought to market after about 2005 or so are considered to be, and advertised as, 'dual mode'. This means they come set to factory defaults and able to detect for themselves what type of energy you are providing them at the rail tops. If only DC, they'll act as designed for DC ops. If DCC, you'll get full functionality out of them and be able to programme all programmable CV's. 

Some decoders 'act up' when operating on DCC, but mostly during the initial power-up at the commencement of an operating session. The locomotives will rush away on their own at full speed. I am not aware of it happening later in a session, but who's to know it doesn't happen. What happens is the decoder senses the power and for some reason takes the DCC voltage, which is always at full voltage at the rails, as a full voltage DC signal, and it will immediately leap into top speed. Very disconcerting.

What you must do, when you first get the locomotive and want to reconfigure the address and motive characteristics, and to alter the sounds to taste, is to also remove that sensitivity that makes it 'dual mode'. That component is enabled/disabled in CV 29. There is a calculator you can use to get the right value in CV 29 for lights, direction of movement going 'forward' for the locomotive (important for long hood diesels in the steam era), and also the enablement for DC ops.

http://www.digitrax.com/support/cv/calculators/


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## CTValleyRR (Jul 26, 2014)

Chops said:


> Thank you, useful information. Based on that, I will scrap my few old MRC decoders as I am keen on reliable operation. That being said, the use of capacitors to "stay alive" is news to me. Can you recommend any such decoders?
> 
> Ideally, I'd like to run three trains simultaneously upon a four x eight layout. Would the AC voltage drop require adding in bus wires?


If you DO experience a significant voltage drop that affects the operation of the locos, then adding feeders is the solution.

However, that EZ Command unit should be able to run 3 locos on a 4x8 without trouble on a single pair of feeders.


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## Chops (Dec 6, 2018)

Thank you again. What decoders would have capacitor built in?


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## CTValleyRR (Jul 26, 2014)

I buy my decoders when I need them, and don't use sound in any case. Since I haven't bought one in several years, I don't really know what's out there at the moment. Last I checked, only sound decoders came with capacitors, but some had plugs to add one. Maybe someone with more recent experience can weigh in with a recommendation.


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## wvgca (Jan 21, 2013)

i bought my decoders from LAIS, not sound but they have bemf and wires for stay alive ..
they were 11$ each, and stay alive was another 3$


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## DonR (Oct 18, 2012)

I have 10 DCC locos, none has a 'stay alive' and
none has ever needed it. I use code 100 flex track
with only a few soldered joiners and about 20
Peco Insulfrog turnouts.

I run my track cleaning car before running trains
if there has been an extended time since last session.

If your track and loco power pickup wheels are kept
clean you should not need a 'stay alive'. I have
never had a stalling or pausing loco due to poor
track power pickup.

Don


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## Chops (Dec 6, 2018)

Sounds useful, Don.


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## mesenteria (Oct 29, 2015)

If we can assume that the motor and its feed via internal locomotive wires are all good, and the gearing isn't locked for some reason attributable to simple wear, then the problems with control and motion come down to corrosion or dirt. That can be from the poor electrical continuity afforded by metal joiners between track elements to the corrosion or dirt on the rail heads, and on to dirty tire treads and even dirty or corroded pickups rubbing over axles or the backs of metal wheels.


Wipe the rails' bearing surfaces, even with a 1" steel washer. It will help. 


Wipe the tires with alcohol, or even with an ink eraser (this works for cordless phone contacts as well when your cordless phone doesn't seem to want to charge).


Invert and inspect the backs of the wheels or the axles, and note the apparent contact between pickups/wipers and their swept surfaces. Are they making contact? Are they clean?


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