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How hot do decoders get?

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DrW
  • Member since
    January, 2008
  • From: Lubbock, TX
  • 137 posts
How hot do decoders get?
Posted by DrW on Friday, February 29, 2008 9:36 PM

In the most recent web page for the Con-Cor Aerotrain there was a warning that caught my attention:  " A small Standard function decoder (no sound), will fit inside the Locomotive body shell and should not generate enough heat to damage the body, just make sure the decoder is NOT TOUCHING the inside of the body shell when you replace the body shell."  I have to admit, while I try to keep incandescent light bulbs away from the shell as much as possible, I never thought about the decoder.  I am using Digitrax decoders, and usually, unless it is very critical to put the shell back on, I do not bother to tape them down.  So far, I never had a problem with an overheating decoder (even in the Bachmann Spectrum saddle tank 0-6-0 where even a Z gauge decoder is a tight fit).   Furthermore, in test runs with engines w/o shell I never noticed that the decoder was exceptionally hot; however, these test runs never lasted more than a 10-15 minutes.  Thus, my question: Did anybody have ever problems with overheating by a correctly installed decoder?  (Yes, I know from personal experience that you can fry decoder by incorrect installation.) 

 Thanks for any information

 JW

  • Member since
    July, 2006
  • From: Winnipeg
  • 234 posts
Posted by Magnum019 on Friday, February 29, 2008 10:39 PM

I run Digitrax Decoders and all of them are just luke warm to the touch, I use two sided tape to secure them.........one problem I had when I first started wiring was improperly hooking up my lights.........engine would run for about 10-15 mins.....and shell was hot enough to fry an egg........was  fortunate enough not to have ruined the shell and did save the decoder.......

 

CJH 

  • Member since
    October, 2004
  • From: St. Louis, MO
  • 941 posts
Posted by river_eagle on Friday, February 29, 2008 11:18 PM

sound decoders, especially the mini ones can get pretty toasty, but not hot enough to melt the shell, unless something goes very wrong and the magic smoke gets released.

generally the smaller the decoder the hotter it runs, just not much mass to

dissipate heat from.

When in doubt, rule #1 applies  Central Missouri Railroad Association cmrraclub.com
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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Saturday, March 01, 2008 12:39 AM
 river_eagle wrote:

generally the smaller the decoder the hotter it runs, just not much mass to

dissipate heat from.

That's where it's handy to have a metal frame to strap it down to. That wat the frame becomes a heat sink.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
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  • Member since
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  • From: Northeast OH
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Posted by jktrains on Sunday, March 02, 2008 7:50 AM
A properly size decoder should not get hot, warm maybe, but not hot and definitely not hot enough to melt plastic.  Most heat related issues come from improperly sized resistors used for lighting.  These can get hot if undersized.  If your decoder is getting hot, these something wrong with it or the install.  Or, you can always open things up a little by removing some fans or grills on the body, look some others have done! Laugh [(-D]
  • Member since
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  • From: Colorful Colorado
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Posted by Texas Zepher on Sunday, March 02, 2008 1:44 PM

In the old days decoders used to get really hot.  I've seen melted down shells and even had one instance where the decoder was mounted upside down and the power transistors melted their solder and fell out onto the track.  BUT today's technolgy should not get nearly that hot.

One thing to be careful of, is to not use foam double stick tape such that it holds heat in.  I always try to get at least a small air cavity all the way around the decoder where components are mounted. 

  • Member since
    June, 2004
  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
  • 25,640 posts
Posted by jeffrey-wimberly on Sunday, March 02, 2008 2:41 PM
A trick some of the old-timers use is to tape the decoder down to the locos metal frame (properly insulated, of course) so some of the heat is absorbed by the frame.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


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