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Decoder failure while idle


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A first for me. While operating last night the acrid smell of toasting electronics made itself known, but everything was running normally. It took a while to spot the source, a quite realistic haze emitting from a Bach class 40, currently standing idle as we are in the 'steam only operation' phase at present.

 

Called up its address and it was standing, no drive (and it has no lights or any other accessories) but sure enough it wouldn't move and was 'decoder undetected' once placed on programme track. Once inside the decoder had clearly cremated itself. First self destruct of a decoder off load that I have seen, so my MTBF estimate for this failure mode is 13 years as it went into service in 2006.

 

Anyone else?

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11 hours ago, Paul80 said:

I once had 2 lenz silver mini decoders die within 30 seconds of each other and both were in the same model of loco, the replacements are still working quite a few years later.

 

Odd things do happen.

Indeed, and I fully expect consumer grade electronics to roll over and die at some point. There's little information about how long decoders might be expected to keep performing that I have seen.

 

The 'infant mortalities' you saw on the those Lenz minis are the kind of thing I would definitely occasionally expect. Seen my share on a half dozen different manufacturer's products (performing installs for several friends over the last fifteen years beside my own) and there was nothing amiss with the mechanisms they were installed on. In every case the next decoder that was installed was fine, and there were no problems afterwards.

 

Likewise, even more occasionally, satisfactorily installed decoders that die while running. On my own locos I lost three Lenz Golds within two to three years of install: the Lenz warranty took care of those, and the replacements have all worked for more than ten years since on the same locos. (Lesser decoders that fold are scrap - inevitably.)

 

But this was the first long time installed decoder that gave up while standing on power, definitely not running, a whole new thing. My estimate is that it has probably had an aggregate circa 10,000 hours on power in its 13 years service. Tested the mechanism and all was well with it, and the Lenz Standard that went in as replacement installed as it should.

 

11 hours ago, WIMorrison said:

Yep, had a Zimo die on me and all CVs read 0 - normal reset didn't work but a hard reset with a series of numbers restored it back to factory default and it has been running like a dream since.

Ah yes, the decoder 'brain fart'. Most of my fleet have Lenz or Zimo, but there are a few of the Bachmann badged ESU lokpilot v1 on centre motor traction. These latter were prone to his problem until I hit on a routine of isolating the DCC system from the layout at power down, and only restoring connection after switching the DCC system on. No incidents since. (Thanks to whoever made that good suggestion on Ur-RMweb; gone but not forgotten.)

 

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  • 2 months later...

I have just experienced a similar event - a Hornby A4 'Herring Gull' with Hornby's original full fat DCC sound decided to go 'pop' and emit large amounts of smoke. It had just had a brief satisfactory run on DCC round my layout with sound on and was sitting stationary by a platform while I ran another loco when it occurred. I quickly removed it from the layout and upon removing the tender body found it had melted the inside of the tender. I then put a blanking plug in and it ran perfectly again (on DC only, of course). There would therefore seem to be nothing else wrong with the loco, e.g. no shorting out, to cause the decoder to burn up.

 The decoder, ESU Locksound V4, was badly burnt around one major component on the board which had obviously caught fire. I  don't understand why this happened and consider it dangerous - I was glad I noticed the smoke before any further damage had been done to the loco (or my house). I bought the loco about 3 or 4  years ago and I haven't run it for a couple of years, but surely this shouldn't happen. I am thinking of sending the chip to Hornby but don't know if they will show any interest or offer a replacement.

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1 hour ago, paftrain said:

I have just experienced a similar event - a Hornby A4 'Herring Gull' with Hornby's original full fat DCC sound decided to go 'pop' and emit large amounts of smoke. It had just had a brief satisfactory run on DCC round my layout with sound on and was sitting stationary by a platform while I ran another loco when it occurred. I quickly removed it from the layout and upon removing the tender body found it had melted the inside of the tender. I then put a blanking plug in and it ran perfectly again (on DC only, of course). There would therefore seem to be nothing else wrong with the loco, e.g. no shorting out, to cause the decoder to burn up.

 The decoder, ESU Locksound V4, was badly burnt around one major component on the board which had obviously caught fire. I  don't understand why this happened and consider it dangerous - I was glad I noticed the smoke before any further damage had been done to the loco (or my house). I bought the loco about 3 or 4  years ago and I haven't run it for a couple of years, but surely this shouldn't happen. I am thinking of sending the chip to Hornby but don't know if they will show any interest or offer a replacement.

Out of interest what DCC controller are you using?

 

Cheers

Dave

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On 01/10/2019 at 11:58, 34theletterbetweenB&D said:

A first for me. While operating last night the acrid smell of toasting electronics made itself known, but everything was running normally. It took a while to spot the source, a quite realistic haze emitting from a Bach class 40, currently standing idle as we are in the 'steam only operation' phase at present.

 

Called up its address and it was standing, no drive (and it has no lights or any other accessories) but sure enough it wouldn't move and was 'decoder undetected' once placed on programme track. Once inside the decoder had clearly cremated itself. First self destruct of a decoder off load that I have seen, so my MTBF estimate for this failure mode is 13 years as it went into service in 2006.

 

Anyone else?

Hi,

 

Depending on the decoder there is a small chance an intermittent connection of decoder inputs or outputs within the loco caused the decoder to damage itself.

 

The only decoder I've seen emit smoke it was probably due to the decoder plug pins going through the socket and connecting with the metal chassis or piercing a wire under the socket.

 

Ten thousand hours under power is a lot. Did the decoder have insulation added around it?.

 

Out of interest which make and model of decoder was it?.

 

 

Regards

 

Nick

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The decoder was an eight pin Lenz Gold. It was in free space above the chassis, with insulating tape on the block to prevent any shorting, something I early quickly learned to be very thorough in preventing with Lenz decoders, after an accident on a friend's split chassis conversion. (Don't bother fitting DCC decoders to split chassis steam mechs was my personal take away from that!)

 

It's been Lenz gold that are troublesome, that's four failures now, first three well within warranty happily. No problems (yet!) with the silvers and later standards. (I started out in decoder fitting with a batch purchase of Lenz golds for the 'stay alive' capability, which I imagined I would use generally. As it turned out, stay alive simply isn't required with DCC, never had to use it yet, and as a result I switched to the silver and subsequently standard decoders for the same drive capability for less money.)

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On 02/10/2019 at 09:21, 34theletterbetweenB&D said:

Indeed, and I fully expect consumer grade electronics to roll over and die at some point. There's little information about how long decoders might be expected to keep performing that I have seen.

 

The 'infant mortalities' you saw on the those Lenz minis are the kind of thing I would definitely occasionally expect. Seen my share on a half dozen different manufacturer's products (performing installs for several friends over the last fifteen years beside my own) and there was nothing amiss with the mechanisms they were installed on. In every case the next decoder that was installed was fine, and there were no problems afterwards.

 

Electronics follows the "bathtub curve" https://en.wikipedia.org/wiki/Bathtub_curve

 

Products that are required to exhibit high reliability will be "burned in". That means running them long enough to weed out the early failures. I doubt decoder manufacturers do that :)

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On 14/12/2019 at 01:29, Hamburger said:

Seems as if one of the tantalum capacitors had blown. 
Was it a yellow component, rectangular shaped?
Tantalum capacitors are very sensitive against over voltage.

 

 
it might have been yellow - can’t tell now as it turned black after it caught  fire!

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On 14/12/2019 at 01:29, Hamburger said:

Seems as if one of the tantalum capacitors had blown. 
Was it a yellow component, rectangular shaped?
Tantalum capacitors are very sensitive against over voltage.

 

Ive known the tantalum cap go in Heljan models, they dont fully agree with the lighting circuits in use...

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