# Locomotive Decoder Started Smoking! Help!!!



## KisNap (Aug 4, 2014)

Hi Everyone,
I installed a drop-in sound decoder board last night and when I put it on the track it began to smoke when I tried to get it to move!
The sounds and light all worked, but as soon as I give it a little throttle the decoder started smoking above where the motor contact is. I ensured that the motor contacts weren't touching and I've installed one of these before and have done other installations of other decoders. It even got so hot that the solder began to melt and became soldered onto the board. Any advise would be greatly appreciated!


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

Ummmm, all I can think of at this point is to buy a new one. You let the smoke out of it.


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## Brakeman Jake (Mar 8, 2009)

Was a load test done on the motor before installing the decoder?It looks like a shorted motor drawing excessive current or a defective decoder,assuming there's no faulty wiring.


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## DonR (Oct 18, 2012)

I agree with Jake.

It sounds like the motor is drawing too much current.

If you have a multimeter do a stall test (without the
DCC decoder connected) on a DC powered track.

Connect the meter in series with one side of the
track feed. Set the meter to AMPS. While holding
the loco by hand, run the throttle up to about 3/4.
Note the amp draw. Then slowly press down on the
loco until the motor stalls. Note the amp draw.

It's my guess the motor is drawing near or exceeding
an amp when running, substantially more when stalled.
Most decoders have a 1 amp motor rating.

If so you'll need either a decoder with amp capability
of your loco motor or a replacement motor.

If the amp draw on stall is .5 or .6 the
problem could be a wiring short or defective
decoder.

Don


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## tkruger (Jan 18, 2009)

Was this a DCC Ready locomotive? Or was this decoder just a drop in replacement? If it was a drop in replacement does it still require you to isolate the motor from the frame? If the motor was not isolated from the frame it is possible that track voltage could enter the decoder through the wires to the brushes. This will also cause it the decoder to burn up. 

Regardless there is little that can be done to fix a smoked decoder.


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## KisNap (Aug 4, 2014)

Are you saying it could be a defective motor? I have another of the same engine and DCC board and they work fine. It's the MRC 1812, 1 Amp capacity.


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## DonR (Oct 18, 2012)

KisNap said:


> Are you saying it could be a defective motor? I have another of the same engine and DCC board and they work fine. It's the MRC 1812, 1 Amp capacity.


That is a possibility. The test I outlined would
determine that. 

The hope is that the decoder has not been damaged though
smoke is not a happy indication. So
disconnect it and test the motor.

You say you have installed a decoder before so we
assume that you checked to see that the motor is
totally isolated from the frame. You can check that
with a multimeter set to ohms. Touch one probe on
a motor tab the other to the metal frame. Do it
with both motor tabs and also the motor shell.
Any reading would indicate
the motor is touching the frame somehow and must
be isolated.

If your decoder is a Digitrax they have a very generous
warranty. Even if, by mistake, you damaged the decoder
they replace it free. See their website for instructions.
If it's another brand see that website for warranty 
possibilities.

Don


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## Brakeman Jake (Mar 8, 2009)

MRC.......,...had three of those junks....all three flamed out.........


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## tkruger (Jan 18, 2009)

I have had MRC motor decoders that burnt up even when the motor was well under spec. MRC QC on their decoders is lacking.


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## CTValleyRR (Jul 26, 2014)

tkruger said:


> I have had MRC motor decoders that burnt up even when the motor was well under spec. MRC QC on their decoders is lacking.


As a fan of MRC DCC systems and DC power packs, I unfortunately have to agree with the above. I cannot recommend MRC decoders at all.

I use NCE, Digitrax, and TCS decoders with my MRC Prodigy DCC system.


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## KisNap (Aug 4, 2014)

The thing I like about them is how the speaker is already attached and you don't need to worry about speaker placement. So far I have 2 of their sound decoders installed and they work well enough especially since it's a drop-in decoder.

Just out of curiosity, sound quality aside, what is it that people don't like about them? Is it their operation of the locomotive or their reliability.

I contacted MRC and they told me to send it to them and they'll repair or replace it.


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## Brakeman Jake (Mar 8, 2009)

UNRELIABILITY!!!That's the only point they're reliable at...just give them a little time.I've had one that ran so hot that it destroyed the shell in the process.


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## tkruger (Jan 18, 2009)

KisNap said:


> The thing I like about them is how the speaker is already attached and you don't need to worry about speaker placement. So far I have 2 of their sound decoders installed and they work well enough especially since it's a drop-in decoder.
> 
> Just out of curiosity, sound quality aside, what is it that people don't like about them? Is it their operation of the locomotive or their reliability.
> 
> I contacted MRC and they told me to send it to them and they'll repair or replace it.


Mine have been fine at the start. They tend to go after a period of time. Also always during longer sessions. I have swapped the ones I had left to locomotives that are only run for brief periods. Or the ones used to build a string of cars and then left to sit the rest of a session.


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## Cycleops (Dec 6, 2014)

So there you have it, a cheap sound decoder with a time limited smoke unit. I've listened to them on YouTube and they do sound rather naf. I'll stick with Tsunamis and ESU thanks.


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## tkruger (Jan 18, 2009)

Cycleops said:


> So there you have it, a cheap sound decoder with a time limited smoke unit. I've listened to them on YouTube and they do sound rather naf. I'll stick with Tsunamis and ESU thanks.


One thing I will say is that their sound only decoders seem to hold up. Using a speaker other than the MRC one supplied also makes a huge difference. The quality is not that of a Tsunami but if you have space in the shell adding sound for $35 is not a bad deal. This said I would not pay more than that considering that a separate motor decoder is needed. 

I think the issue is the motor controller and their speakers. I have noting to prove that but I am yet to have a Sounder (sound only) series fail.


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