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MRC 1636 decoder question

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  • Member since
    December 2007
  • 88 posts
MRC 1636 decoder question
Posted by Walleye on Thursday, February 7, 2008 9:52 AM
I recently had an MRC 1636 sound decoder installed into a new DCC-ready Atlas GP40-2 (retro-fitted with an Aztec frame to hold the speaker). This loco has no real low-speed capability at all. At very low throttle settings, it will not move at all, then it abruptly takes off at moderate speed. It isn't quite a jackrabbit, but its slowest speed is too fast for prototypical yard work (mating MTL couplers, for instance). I've fiddled the acceleration and start-up CVs and tried all three of the hard-coded speed tables - same response. Since I only ran this loco very briefly before putting in the decoder, I don't know ifit had a motor drive problem to start with or if the decoder is doing this.

I have several Atlas GP40-2s with the factory-installed LE063XF decoder. All run great and have excellent low-speed performance. On step 1 of 128, they will move at a barely discernible creep, and will increase speed smoothly from there.

 Does anyone have experience with MRC1636 decoders? Is this typical performance for them? Or should I look for a problem in the motor drive? While I love the sound (it's my first sound-equipped loco), I'd be willing to replace the 1636 with a non-sound decoder if that would get me better performance.

-Walleye

-Wayne Ryback "Illegitimi non carborundum!"
  • Member since
    December 2007
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Posted by Walleye on Thursday, February 7, 2008 3:20 PM

Oooooh! Read some of the previous threads. Realize how lucky I am - my 1636 actually works! (So far. Sigh [sigh]) So the bunnymotive starts are a feature. Time to swap in a Digitrax, I think.

And thanks for the advice, Dave.

-Walleye

-Wayne Ryback "Illegitimi non carborundum!"
  • Member since
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Posted by hobo9941 on Friday, February 8, 2008 9:49 PM
I have a problem with the fast starts too, with a couple MRC decoders, although several others are OK. It never occured to me that the decoder might be the problem, with the fast starts. However, I love the MRC 2nd gen diesel sounds. Can I use another decoder for motor control, and keep the MRC for the sound? If so, do I need to put some kind of load across the MRC motor leads?
  • Member since
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  • From: Eastern Shore Virginia
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Posted by gandydancer19 on Sunday, February 10, 2008 12:22 PM

 hobo9941 wrote:
Can I use another decoder for motor control, and keep the MRC for the sound? If so, do I need to put some kind of load across the MRC motor leads?

I haven't tried this myself, but I don't see why it won't work.  And yes, you will probably need a load resistor on the motor output leads.  That's what NCE decoder testers use. (a resistor)  I'm not sure of the value, but if you make it kind of high, it will draw less current from your track, but it still has to be low enough to make or allow the decoder to work.  Maybe try 200 ohms @ 5 watts to start with.  Both decoders should be set to the same address.  I don't know if you will be able to program two at the same time on a programming track, but you should be able to do it on the main in POM mode.  One thing that you might want to do is connect a separate track up to your system and disconnect your layout for programming this special configuration so you don't wind up resetting all of your locomotives.  Or you can remove all of your locomotives from the layout while you set it up.  It depends on how big your layout is and / or how many locomotives you have.  If you do get it working, make sure that the resistor is not close to any plastic.  It may get hot.  If it does get hot and starts to smell, try using a higher wattage resistor in its place.  (P=I x E is the power formula, so 0.5 amps of motor resistor current draw times 12 volts = 6 watts.)  You probably won't get 0.5 amps of current using a 200 ohm resistor, so the 5 watt resistor should be OK, but keep an eye on it for the first hour or so of running.

Elmer.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

  • Member since
    January 2007
  • From: Eastern Shore Virginia
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Posted by gandydancer19 on Sunday, February 10, 2008 12:31 PM
 davidmbedard wrote:

Do a search for MRC decoders and grab some popcorn.  MRC has a horrible reputation around here when it comes to their decoders.  Bottom line....avoid them at any cost.  There is no 'good' MRC decoder.

David B

Well, I guess I am going to learn the hard way.  I just put a bid on eBay for a 1626.  I was looking more at the sound functions than the motor functions, plus the 1.5 amp suited me better than the 1 amp models that most everyone else has.  I didn't look close enough at the motor functions, like being able to set up starting pulses.

Elmer.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

  • Member since
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Posted by Anonymous on Sunday, February 10, 2008 1:13 PM
Back emf is what you want. MRC aint got it and never will get it.
  • Member since
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Posted by Tilden on Sunday, February 10, 2008 8:26 PM

The MRC 1650/1651 decoders have BEMF.  I'm not sure about any of the sound ones.

The "kick" start features such as found in the 15 series NCE docoders are a nice feature.

Tilden

  • Member since
    February 2008
  • 1 posts
Posted by crossword chris on Monday, February 11, 2008 3:17 AM

     I tried the Aztec chassis setup and found it to be a marginal product at best.  The same thoughts I have about the 1636 decoder.  I broke the speaker wires off of 2 decoders an ruined them by trying to resolder them back together.  Finally on the 3rd attempt, I got the decoder installed.  I tried the same method to program the decoder because thats how they talked about it on Aztecs web site.  I ended programming it on Decoder Pro 2.1.1 and had no problems with low speed or with using a Digitrax radio equiped throttle.

     When you into Decoder Pro MRC synchronized sound decoders 1636, it only has a few ways to program a speed curve an thats it! The best I could tell, these decoders just have factory pre-programmed speed curves and thats it.  You can't program in your own curve, and you have to program different brands of decoders to match MRCs speed curves or they don't run well with other equipment.

     The real gripe I have is the speaker fires up into the completely enclosed bottom of the metal fuel tank and you can't hear the diesel engine at an idle or when it revs up. The horn, bell, brake squeel and other sounds are sound pretty decent.  I called the guy at Aztec trying to get help, and he copped an attitude with me.

     Overall, it is a neat idea.  I think the Aztec frames need more development to make installation easier than what it is, and MRC could do a lot better job with the quality of their product for $85.

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