Heat Generation from Decoder

[Pendragon Sailing]

I’ve noticed that these new decoders seem to create quite a lot of heat. Not having used DCC before, I have no frame of reference for how warm decoders can get.

When installing them in some of the smaller locos, where internal space is scarce, has anyone experienced any issues from heat build-up?

I’m concerned that if running a loco for more than (say) 10-15 minutes at a time, that the trapped heat might cause the chip to overheat and perhaps damage it.

Any views on this?

[96RAF]

I have only had one 8-pin TXS decoder overheat and I think that was damaged by a loco fault. The rest run very cool.

Despite running at extreme heat (too hot to touch) it was still working. I only spotted it when I went to re-rail the errant loco and thought that is a tad warm.

It got sent back for investigation but I have not heard back about it yet.

If you have a decoder test rig or known good loco try it in there to rule out a dodgy loco like mine.

[ColinB]

That might explain why some people are having issues. Interesting as TTS had this sort of issue. Other manufacturers heat shrink their devices to reduce the danger of their parts touching the chassis of the loco and dying, but if you were to heat shrink a TTS decoder it generally overheats and dies. The only thing I can say is make sure that there is a means for the heat to escape.

[SteveM6]

Only anecdotal evidence, but I use a clear heatshrink on all my decoders (including TTS and HM7K) and so far have not had an overheating issue at all.

[96RAF]

That might explain why some people are having issues. Interesting as TTS had this sort of issue. Other manufacturers heat shrink their devices to reduce the danger of their parts touching the chassis of the loco and dying, but if you were to heat shrink a TTS decoder it generally overheats and dies. The only thing I can say is make sure that there is a means for the heat to escape.

 

 

I have had this robust TTS decoder swaddled in my pannier tank tender for years and it still works.

[ColinB]

I had a TTS in my class 43, heat shrinked. One hot sunny day in the loft running quite happily doing laps of my railway when it suddenly died. It wasn't the first either. Since then I have loosely covered them with heatshrink and have had no issues. Perhaps I was just unlucky but in their original instructions Hornby advised against doing it, whereas all the Zimo 8 pin decoders come covered in heatshrink. They have recently stopped doing it mainly because it causes issues if you want to add wires not because of any other issue.

[Pendragon Sailing]

Thank for the guidance folks.

I’ve just fitted an 8 Pin chip into my Bachmann 08 shunter.

It was a very tight fit, and I was concerned that given the very small space it occupies (behind the front radiator), that I might be heading for a problem with the heat it generates. I have drilled a small hole in the loco’s ‘chimney’ to allows some of the heat to escape. For the record, the speaker has been fitted inside the cab.

I’ll keep an eye on it and report back if I encounter any issues.

[DarkRedCape]

I’ve wondered about this. I use Kapton tape on all my decoders, just enough to go round the decoder about 1.5 times with a pretty loose fit, and open at both ends.

To wrap or not to wrap your decoder seems to be a marmite subject. Even Kapton tape seems to be a method some are for and some against. I like it because it leaves no sticky residue like duct tape does.

[Rallymatt]

There is some heat from HM DCC Next18 decoders in my TT:120 locos , one Hornby and one Piko, (my Zimo equipped Roco locomotive has lost all motor control and has been returned to Roco in Austria to sort out) in both the the HM DCC installations there is an amount of air gap around the decoders and no metallic parts to contact.

For those that have metal chassis parts close to decoders, would it be wiser to put the tape on the chassis rather than around the decoder?

[Daedalus]

Why not use a piece of paper it is an excellent dielectric.

[96RAF]

Why not use a piece of paper it is an excellent dielectric.

 

 

Unless printed with a graphite based ink in which case it is an excellent conductor.

Taping metal parts is a good idea but a single layer of Kapton tape on the decoder is also a recommended method.