How hot should a decoder be?

[jxtrrx]

I took the hood off an Atlas locomotive to change a light bulb, and when testing (hood off) touched the decoder... so hot I couldn't leave my fingers on it.  Is this trouble?

[jeffrey-wimberly]

What brand decoder is it? If it's getting that hot it must be running right at the edge of it's capacity and can blow at any time.

[selector]

Heat and static discharge are two of the greatest enemies of electronics.  I have never felt any of my engines get that hot when I handle them.  I would think it wouldn't be doing the shell much good, either.

[jeffrey-wimberly]

Ditto to that Crandell. I would hate to see the shell of an expensive loco like an Atlas get deformed by an overheated decoder. Just the thought of it makes me cringe!

[tstage]

Jack,

Some decoders require adequate ventilation to keep cool.  If you have the decoder secured/covered by electrical tape, this could be the problem.  A few additional questions for you:

• How is the motor?
• Is it also hot to the touch?
• Which decoder do you have?
• Did you install it, or did it come with the locomotive - i.e. factory installed?

Tom

[cacole]

Certainly not as hot as you describe.  You're lucky it hasn't burned out if it's that hot.

How long had you been running the locomotive and how much weight was it pulling?  If you're overloading the motor by pulling too much weight, the decoder will overheat and eventually fail.  Lack of adequate lubrication could also be a factor.

[jeffrey-wimberly]

I took the hood off an Atlas locomotive to change a light bulb, and when testing (hood off) touched the decoder... so hot I couldn't leave my fingers on it.  Is this trouble?

Do you have the decoder on top of the motor? If so tyhat might be your problem. The motor in my Atlas GP40 runs pretty hot (1970's 5-pole can motor, what can you expect) in long haul operation. I placed the decoder atop the rear truck with double sided tape. Little chance of an overheat there.