Smoking hot Fleischmann loco

[Weardale Wanderer]

I was testing a loco of mine a little while ago, a Fleischmann BR 70 (4070) on DCC.

 

It was running nicely until, on a straight piece of track, smoke starting pouring out of it. It was still going, and didn't trip out.

 

I took out the decoder and it was red hot. Replaced the chip with a new ESU one, but now all that happens is the front and back lights flicker constantly. No signs of life.

 

I'm obviously thinking a short, but perhaps the motor ? It looks okay but I haven't tested it yet.

 

Has anyone any thoughts before I go into a deeper dive?

 

Cheers,

 

Mark

 

 

[Crosland]

Decoders would normally go bang and maybe let out a puff of the "magic smoke". Anything more than that is probably internal wiring, maybe the varnish on the motor windings.

[34theletterbetweenB&D]

Test the 'smoked' loco with the DCC blanking plug in place on DC. That the decoder was very hot when removed tells us that there was high current draw when the smoking occurred. Top suspect for what was happening was the varnish on the armature windings melting and vaporising; that typically leads to a permanent short in the motor windings. But don't lose all hope yet: I have had clouds of smoke out of RTR OO running on DCC which have turned out to be from failed inductors (simple replacement with a piece of wire) or a failed capacitor (snip it off, redundant in DCC which has its own RFI suppression)

 

I would test both decoders in another known reliable mechanism: full drill, install decoder, attempt address change on programme track to verify that this much of the decoder is working, then if there is no fault code, try on DCC power.

[WIMorrison]

I wonder if this was an old loco that had been running for a while and suddenly the decoder got hot, or was it a loco that you had just fitted the decoder into and after running nicely for a short while it went up in smoke?

 

If it is that latter might I suggest that the decoder you have fitted isn't rated at a high enough current for the loco?

[Weardale Wanderer]

Just had another one pop tonight.

 

Both were Fleischmann locos that were quite old but that second one I'd hard wire converted to DCC. The first was DCC ready. They'd worked great for a while but had been in storage for a good few months.

 

The second loco, again a small one, didn't give off smoke but is just sitting there with its lights blinking on and off.

 

I think they both have those little rectangular open frame motors. I'm going to have a good look at them this weekend. 

 

 

Edited December 13, 2023 by Weardale Wanderer

[Weardale Wanderer]

2 hours ago, WIMorrison said:

I wonder if this was an old loco that had been running for a while and suddenly the decoder got hot, or was it a loco that you had just fitted the decoder into and after running nicely for a short while it went up in smoke?

 

If it is that latter might I suggest that the decoder you have fitted isn't rated at a high enough current for the loco?

Option 2 by the sounds of things : It had been running nicely for a short while, put into storage, tested for a few seconds and then up it went.

 

The second loco went the same way, but no smoke. I can still access its settings in DCC and it makes a sound, but no movement.

 

All very odd, and a bit worrying. I don't want to risk any more 'popping' like this.

 

The first chip was Soundtraxx I think. The second was train-o-matic, which suprised me. I find the chips to be very good.

 

More investigation is required.

 

 

 

[Weardale Wanderer]

I'm wondering - Both these locos use very small bulbs, rather than LED's. If I replaced these, would it make any difference to current draw, or is this down to the motor? I'm tempted to try and replace the motors with coreless ones.

 

Any thoughts?

[Harlequin]

You need to find out what went wrong before trying to "fix" things.

 

Have you got another, non-Fleischmann loco you could test? I.e. one with a completely different motor that you would be willing to sacrifice if it too has a problem? If so, try it with different decoders in.

 

What are the flashing lights from the ESU decoder about? Is that an error indication, perhaps?

 

When you get inside one of the Fleischmann locos that has emitted smoke, how about posting some photos here for us to look at?

 

[WIMorrison]

2 hours ago, Weardale Wanderer said:

I'm wondering - Both these locos use very small bulbs, rather than LED's. If I replaced these, would it make any difference to current draw, or is this down to the motor? I'm tempted to try and replace the motors with coreless ones.

 

Any thoughts?

The size of the bulbs doesn’t reflect the current draw. I know that on some of my Bemo locos the bulb can draw 100mA which when added to the current draw on a 00 motor could well take you over the top resulting in overheating.

 

However at the moment we are guessing in the dark as we don’t know what loco(s) you are using, we don’t know which decoders you are using nor do we have a stall measurement of the current draw on DC to advise anything definitive.

[Weardale Wanderer]

On 14/12/2023 at 17:53, WIMorrison said:

The size of the bulbs doesn’t reflect the current draw. I know that on some of my Bemo locos the bulb can draw 100mA which when added to the current draw on a 00 motor could well take you over the top resulting in overheating.

 

However at the moment we are guessing in the dark as we don’t know what loco(s) you are using, we don’t know which decoders you are using nor do we have a stall measurement of the current draw on DC to advise anything definitive.

 

The two locos I have that are the source of my problems are both Fleischmann. One is a BR89, the other a BR70.

 

Both are small locos with each utilising the same type of motor (Photo of same design motor, but not the actual ones I have):

 

The first loco that went up in smoke was DCC ready (The BR70), which was fitted with a Gaugemaster chip (This was a 90 degree bend 6 x pin version).

 

The second to go (The BR89) was hard wired by me with a replacement LED bulb for the front and a Lokommander 2 micro chip. It has no rear facing light.

 

The gaugemaster chip is dead and was the one that got so hot it emitted smoke, whereas the Lokommander one is fine.

 

I swapped out the burned gaugemaster chip for a Lokpilot model which is what simply gave the flashing 'on and off' front light. Not sure if this is 'code' for anything. In any case, it became apparent the motor was faulty.

 

I have tried swapping out one of the motors (In the BR89) for a coreless one and although this works it makes a horrible grinding sound. This believe is most likely down to the gears not meshing properly.

 

There appears to be a similarity between the two locos in regards to the original open frame motor type and the demise of said motors when used with DCC. Not right away, but after be stored for a little while the same thing happened - dead motor.

 

Finding replacements for these is not proving easy, and even if I did find them will the same problem occur?

 

Another point is that the Gaugemaster chip was the one that was smoking. I thought about posting pics of the locos, but honestly they both look absolutely fine. There's no insulation broken or melted. The motors look fine too. However, I took the body off one of the locos and put it on the track. The motor jerked a little, then quite literally glowed like a light bulb. Still no sign of any actual damage though.

 

If anyone can advise me, in non too technical terms, how to test for current draw, stall measurements and the like, I'd be grateful. I've tried looking it up on line, however people tend to talk about these things as if we all know how to do it already! I am self taught and rely on forums and youtube etc to build my knowledge. As such I very much appreciate any and all help offered by my more learned fellow hobbyists. :)

 

Happy Christmas everyone.

 

 

 

 

[WIMorrison]

The open frame motors work well with DCC, most of my models have the 3 pole open frame, the better ones have 5 pole motors, but still open frame. A 6 pin decoder is really designed for N Gauge (which is what I suspect that they will say in their blurb), though it would work in smaller 00/H0 models - provided the current draw is low - 6 pin decoders are generally 500mA or less though they will allow a higher stall current.

 

To measure the stall current is easy, but you will need a multimeter (MM) and a DC supply. Switch the MM into current reading (indicated by Amps, or Milliamps and use a higher range e.g 1 A or 10A. Connect the MM to the power supply on one side and the loco on the other, connect the other terminal of the power supply direct to the loco and read the running current. Then gently increase the resistance on the wheels until they stop and read the value - this is the stall current.

 

Look at the decoder specifications and you should see at least two value, a steady current value e.g. 750 mA, and a higher value e.g. 1.5A. The lower value should what you are allowed for normal use and the higher value shows what the decoder should take before it destroys itself. If the test shows you are drawing 450mA then don't get a 500mA decoder as that will almost certainly be running to hot for continued use. get one with some headroom e.g. 750mA or more.

[TinTracks]

8 hours ago, Weardale Wanderer said:

f anyone can advise me, in non too technical terms, how to test for current draw, stall measurements and the like, I'd be grateful

 Hi. Seasons Greetings.

 When I got back into model railways during the first lockdown I found the above video very useful as I definately needed a refresher course. OK it's mainly aimed at old ''Dublo Dodgers'' like meself but the basics of electronic testing are the same. 

 Hope this is of use, Cheers, Rich

Edited December 25, 2023 by TinTracks
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