# Decoder reliability question



## WVRR (Feb 6, 2016)

Good evening.

I'm fearful of starting a fight here but never the less here goes...

Our club runs a large - ish layout that is also open to the public, by donation, 6 to 10 hours a day 364 days a year. The public initiates train activity by simply pushing a big green button down a 'kid level'. When they do that a DCC signal is applied to the track and trains (three of them) move out and on to the next programmed stop. They wait there until all 3 have come to their station and the big button is enabled again.

We have been using a Digitrax system since we started back in early 1995 and it has served us pretty well I guess. There is always some small problem but nothing that kept us from opening the doors. We have managed to keep it up to date by having Digitrax do the upgrades we needed. 

Now the issue at hand: As the guy who gets called in from home when things crash it was pretty easy to see that some locomotives just didn't want to start from time to time. ???? The decoders have been replaced on spec but it still happens. Anyway, when I get there and find a locomotive stalled at it's stop I find I can always get it running again simply by lifting one side off the track and putting it down again. Off it goes to it's next stop.

That tells me some things. (1) The engine is getting a good strong DCC signal - or it wouldn't move at all, (2) track is clean because the other 2 engines are using that track without any issues and (3) the particular engine itself is likely ok because it works for hours after the initial problem. 

Question then: Are some decoders simply not very reliable? Are there decoders on the market that do not respond every time? Is expensive really better? 

I'd be very interested in hearing, here or perhaps off list, if others have had similar reliability issues with some decoders, from some makers, and what did they eventually use. Reliability is vital. My gas bill is my own.

Thanks in advance.

Dave at [email protected]


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## DonR (Oct 18, 2012)

I have nine Bachmann DCC locomotives. Seven of them
have the original Bachmann decoders. I installed Digitrax
decoders in the other two. I have not had any decoder problems
with any of the locos. But then I don't run them as much
as your club does I assume.

Some time back a member posted a problem with a DCC loco
that was similar to yours. The loco did not function correctly
and lifting it as you did caused it to go again. 

Others have reported that their decoders would react to a
minor current loss such as from dirty track or a dead frog.

I wonder if a minor current interruption from the track to
the decoder could be the cause on your layout. 

Electronics are sensitive to even minor current deviations
which a loco moving on a track would normally encounter.

We are even instructed to pull the wall plug when a
electronic device fails to function correctly. This causes a reset of
sorts.

Sometimes resetting the decoder to factory default and starting
over has helped.

You mention that you have 'stops' where presumably the locos
are halted. Do you have some sort of DCC device that controls
these 'stops'?

Don


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## Roundhouse Foreman (Jan 6, 2015)

Dave,

Have you tried adding a "keep alive" capacitor and resistor circuit to the decoders to control current loss or interruption?
Are they pole motors or skew motors?
You may just hit a random dead spot on the armature if they are pole contacts vs slanted skew motors which do not have dead spots.
CV 116 & 117 set OK?

RHF


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## CTValleyRR (Jul 26, 2014)

I would not use MRC decoders; other than that, I have used Bachmann, TCS, NCE, and Digitrax ones, all without trouble. Some decoders have different current ratings / limits. If it's a high draw model, and track voltage is near the low end, that might cause the issue you describe.


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## WVRR (Feb 6, 2016)

Roundhouse Foreman said:


> Dave,
> 
> Have you tried adding a "keep alive" capacitor and resistor circuit to the decoders to control current loss or interruption?
> Are they pole motors or skew motors?
> ...


Thank you. That's a road we're looking down now. I think I have eliminated the decoder manufacturer issue as this happens with more than one engine and more than one type of decoder, There is a 'super-cap' device that is available from NCE but it's really pricey for what your actually getting. 

This device is intended to see the decoder over small dead spots rather than hold data for minutes - or hours - between use. THAT"S my problem.


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## WVRR (Feb 6, 2016)

CTValleyRR said:


> I would not use MRC decoders; other than that, I have used Bachmann, TCS, NCE, and Digitrax ones, all without trouble. Some decoders have different current ratings / limits. If it's a high draw model, and track voltage is near the low end, that might cause the issue you describe.


That's my next target. I scoped the LocoNet and found the DCC data attenuated considerabley in the area of concern. New lines, with fewer connections and new, proven connectors is in the works. I'll know by next week.

At the same time, I noticed that it was two Life Like locomotives that were acting unreliably. May have just been the LL wheel/track conductor arrangement.

Much thanks to everyone.


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## mesenteria (Oct 29, 2015)

I have had failures in QSI and in LokSound...one each. I don't use my locos very much, perhaps an hour or two each per year, and I have many that are less than seven years old. I may have a second QSI failure, but won't know for a few weeks before I can diagnose it. It's in a ten-year-old P2K SW8.

I think internal connectivity problems and dirty track account for about 85-90% of the aggravating stops and starts we experience from layout to layout. It might be a broken solder, a broken wire, an intermittent wire short, dirty wipers, dirty tires, or simply track that isn't as oxidation-free as our eyes suggest. Also, some track is a bit wobbly. Maybe not to the eye, and many other locos might run over the wobbles just fine, so we don't notice. But the one locomotive will stumble, stop, and restart every time going over that spot. Longer frames can have this effect.


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