Decoder lifespan?

[kylewoody]

Hey guys,

Was just wondering - do decoders break a lot, or last short time compated to just a DC loco? I don't want my Athearn Challenger to break... I've heard as well, don't spike the throttle to setup the max voltage (I'm running DC, with it's built in DCC remote thingie), instead go up slowly.

Thanks!
Kyle

 

[CanuckMark]

Well, it is electronic so technically it should last "forever". But of course that all depends on how it is used.

You suggested not throttling up quickly, that's probably good advise. On a well designed decoder fed by a well designed power supply/throttle, the only components that should get any real workout should be the MOSFET power chips. And most of the ones they're using are rated for pretty high power transfer, usually 2 amps or so.

One thing that can accelerate the demise of the MOSFETs is a poor quality motor or one that stalls/shorts out.

Mark

 

[SpaceMouse]

They last until you let the smoke out of them. Once that smoke goes, they just don't work no more.

 

[Selector]

Let's assume everything has come together to make a truly perfect decoder. All the components are excellent and fully integrated so that the decoder is a marvel...top quality. After that, the single greatest danger on a continuous basis is going to be heat. If your motor is running hot and you have this truly excellent decoder resting atop the motor, or close to it, with only some electrical tape between them, you can expect the theoretical lifetime to diminish commensurately.

In other words, if the electronics are top notch, are clean, kept clean, assembled well, and not worked too hard (and that includes heat) the decoders will last for lifetimes in normal use.

 

[UP2CSX]

In my limited experience with electronics, there only one other cause of failure that hasn't been mentioned. That's infantile failure, the small percentage of electronic equipment that fail shortly after being placed in service. I've had several decoders that worked fine for a couple days and then gave up the ghost. Sometimes it's because of poor production or a defect in assembly but most of the time it seems to be related to something like sunspots on Mars. Otherwise, heat is the big enemy, as Crandall wrote. After that, it's the quality of the motor and shorts, which is when the smoke comes out. I don't know if there's been any studies done about MTBF (mean time between failures) for decoders but it would be interesting to know what the expected lifetime, under perfect conditions, really is.

 

[kylewoody]

Cool, thanks guys. Like I've said before, I'm still just getting into this hobby, so I've got some dumb questions...

I figured they should last for a long while - just was curious about reliability or anything to help them last longer. Closest hobby I've done is R/C planes - my dad once built an A-1D Skyraider with about a 70" span. Powered by a .61 motor, he said it was beautiful and scratchbuilt. He wrecked the thing due to faulty electronics in the thing at an airshow - the throttle stuck WOT, with ailerons and rudder deflected for a sharp left turn. He said the largest recognizable piece was the cylinder from the engine.

That was the late 1970s - appearantly a wire came unsoldered from the battery pack, so all servos remained at last known position. He still tells the painful story to this day!

I've wondered about that too Chip - seems whenever that smoke comes out, electronic stuff breaks! I figured all those circuitry gizmos were more advanced than running on smoke... cars work the same way.

Kyle

 

[CIOR]

I've got decoders still going that I installed in 1999. So almost 10 years thus far and some with hard run time on them.

The new generation of decoders are being made with cheaper materials and I have noticed more issues with them. I had never fried a decoder until recently, and it was a bad decoder.

But 80+ decoders on engines thus far, it is all good.

 

[UP2CSX]

Very interesting information, CIOR. You must have have gotten into DCC in the antediluvian age of the concept. Given your experience, what's your rating for the most reliable decoder?

 

[CanuckMark]

...The new generation of decoders are being made with cheaper materials and I have noticed more issues with them...

Yeah, that's not surprising. A good parallel to that is VCRs - open up a VHS machine from 1990 and look at its internals, then a last gen unit from 2005 or so. Even the weight alone will tell you they're built way different.

The other problem is the parts for those early decoders will get harder and harder to find should one ever fail. That's why I stocked up on MOSFETs (the most common failure point) for my current NCE decoders now instead of when I need them - at least then I'll have a few just in case.

Mark

 

[hamltnblue]

Actually electronics have gotten more reliable and better over the years.
What seems to be cheaper built actually isn't. Improvements in materials and manufacturing methods have reduced heat generation and have resulted in higher reliability. You will find that sticing with manufacturers that have been in the business longer is the best bet. Chances are that they have alot more experience and lessons learned considered in their designs, resulting in less failures.