Tomix and DCC

[alpineaustralia]

The Tomix motors also draw more current, especially when stalled.

This is what I have been saying guys. The Tomix motors need more power to get going and keep going.

 

 

Alpine, I wonder if its possible your 300 or Doctor Plough stalled at some point (maybe not during that particular incident), and overloaded the decoder

?

 

I have since changed decoders and they still bahave consistently with mrpig's description ie.  "My 300 needs the start volts (CV2) set to 25 before it will start to move at step 1. The Doctor will begin moving with CV2=2, but I would call it more of a lurch. They both behave a lot better after a couple minutes warm up. "

[CaptOblivious]

The Tomix motors also draw more current, especially when stalled.

This is what I have been saying guys. The Tomix motors need more power to get going and keep going.

 

Well, the power needed to get going isn't so much of an issue—even if Vmin is set comparatively high, say to 25 or more, the current draw is likely well within the max of most decoders, so I'm not particularly interested in this fact (although it is telling). What interests me is the stall current, which is the current drawn when the rotors are locked—the maximum current a motor will draw, and the current draw at full load at 12VDC. These numbers may exceed the max ratings of some decoders.

 

Alpine, what I was wondering was, did your locos ever stall prior to failures? If not, were they run at full voltage for an extended period of time just before failure? I'm trying to determine if the failures could be attributed to exceeding the max continuous or max peak current draws of your decoders. Another thing to do, which would be tedious, would be to measure the stall current and max non-stall current draw of the motors (i.e., while hold the motor output still at 12VDC, and while hauling a full load, perhaps uphill, at 12VDC—really hard to measure!)

 

 

What I'm after, overall, is a pattern to the failures that people have experienced. Could anyone else who has installed a decoder into a Tomix train—failure or not!—chime in and tell us your experiences in gory details?

[CaptOblivious]

I have since changed decoders and they still bahave consistently with mrpig's description ie.  "My 300 needs the start volts (CV2) set to 25 before it will start to move at step 1. The Doctor will begin moving with CV2=2, but I would call it more of a lurch. They both behave a lot better after a couple minutes warm up. "

 

Hang, on, I think this is news. I thought before, that they stopped running after a while. But now you say you've put new decoders in, and they run (if lurchingly)? And they run OK if you remove the decoder? Would you mind telling us here the complete story of your failures, just so we have it all in one place?

[mrpig]

Here are the numbers guys.

 

Testing was carried out on the LRL RR (Lounge Room Loop RR), so sorry this is motor car only and no grades.

DCC system was a Digitrax 8amp super chief which has the track voltage set to 12V.

Meter used was a Tektronix DMM870 inserted between command station and power supply. I don’t have a proper dcc meter to measure track current so this is the next best thing. The meter is lab quality and calibrated.

Power supply is a 29amp switch mode set to supply the command station with 14V.

All figures have been corrected for the 2v difference between the point of measurement and the actual track voltage. Eg  current = (measured current – command station current) * 14 / 12.

 

Note that there is a small loss due to command station losses, but it is negligible.

 

Current draw in mah.

 

 

                              Min smooth speed      Max Speed    Stall

Tomix  300 with M1                32                  205          828

Tomix  923 with DZ125            78                  204          700

Kato  500 with DZ125              26                  166          564

 

 

Off topic but still interesting to help determine layout power requirements.

Single interior lighting units draw the following;

Kato 21mah

Tomix 14mah

Microace 27mah

 

Digitrax command station draws 122mah when in sleep mode and actually draws 2mah less when on. :o

 

Big note here.  The Tomix 300 end cars have 12V lamps instead of led’s. They draw 75mah each which means that an approx 30ohm resistor should be used to prevent the inrush current from damaging your decoders. I have to revisit mine now that I know this. :'(

[CaptOblivious]

mrpig, you are awesome! This is very good data to have. And it looks like that Alpine's and others' problems are likely not a result of a too-high stall current. Great, one hypothesis we can set aside.

 

 

(As an aside, I've found these decent replacement for Tomix bulbs; I have a few in my possession I'd be happy to send you: http://www.mcmelectronics.com/product/25-1370)

[mrpig]

I think some of the problems with the Tomix trains are only really apparent because we can normally run trains a lot slower on dcc compared to dc. I think they would not show up on dc and therefore we think there is something wrong on dcc when there is not. Except of course for any fried decoders. Just my thoughts.

 

Capt - thanks for the offer but it is less work for me to install a single resistor on the bulbs, just like Kato do with their light boards

[CaptOblivious]

Just a idle thought—what effect would the capacitors have on back-EMF? Likely this is totally the wrong tree to bark up, but I wonder if excessive back-EMF might be frying decoders? Is this even a real possibility?

[Martijn Meerts]

I've been thinking a bit more about this, but I just can't find a reason why Tomix trains cause more problems than any other trains.. I've converted locomotives that are 25-30 years old, including their motors, without problem, and I'm pretty sure those draw quite a lot of current.

[alpineaustralia]

I am now officially confused by what you guys are suggesting - you lost me about 3 posts ago.

Are we any the wiser as to why Tomix dont behave like Kato?

[CaptOblivious]

I am now officially confused by what you guys are suggesting - you lost me about 3 posts ago.

Are we any the wiser as to why Tomix dont behave like Kato?

 

Nope! We've figured out:

 

That some Tomix motors have slightly higher current demands than some Kato motors, but this isn't a big deal. As Martijn points out: Many older trains have dramatically higher current demands than current Kato motors, but these haven't posed a problem for DCC installs.

 

That the CL system is likely not a factor.

 

That the capacitor found in some models is likely not a factor.

 

That there is no real (or at least discernible) difference betwen Tomix motors and Kato motors.

 

Therefore: The motors are probably not a source of dead decoders. We must be overlooking something?

[alpineaustralia]

Let me pose the question a different way. Has anyone succesfully installed a decoder in s tomix shinkansen without these problems?

 

Could it be a bad batch of trains?

[Martijn Meerts]

Okay, so since it's about 99% certain I will be moving back to the Netherlands later this year, I have started packing up some seldomly used things. That means I'll get a bit more space in my room in not too long.

 

This in turn means, I'll have some space to set up a bit of a workstation for decoder installation. I should have a few decoders left somewhere (both motor and function decoders), and I'm planning on installing one in a Tomix shinkansen to see what happens. Not sure which shinkansen, but it'll likely be the hikari rail star, the dr. yellow, or the 800 considering those have only 1 motor car (and I only have 1 motor decoder I believe).

 

Might still be a few weeks though, since I first need to clear some room in the basement to temporarily store the boxes of packaged stuff, and then figure out which things are actually "seldomly" used ;)

[alpineaustralia]

Please keep me posted on how you go.

[CaptOblivious]

And, as soon as I can afford it, decoders will be going into the Tomix 209-0 I recently acquired from you, Alpine, the results of which I will naturally post here.

[alpineaustralia]

I hope and trust that you will have better luck than me with Tomix matey.

[Martijn Meerts]

I've opened up my Tomix Dr. Yellow motor car today, and I can't see anything special at all. It does have the capacitor, but other than that it's your standard 3 pole motor that hundreds of thousands of model trains world wide have been using for many years ;)

 

I'll be installing a Lenz Gold Mini in it in the next few days, once I get to the point where I've cleaned/packed enough to reach my soldering station which is packed in its box somewhere underneath lots of other stuff =)

 

 

On a side note, all the gears and motor bearings are about as dry as the Sahara, so it would make sense the thing is a bit noise. I'll be using some Marklin oil for the bearings and Tamiya ceramic grease for the gears, which should help a little bit.

 

I will of course take pictures of the entire process and post them when I can.

[alpineaustralia]

I still maintain that the motors are different. The Tomix motors in my two trains are stronger and more powerful than Kato but stop easier and harder to get going than Kato and they do not have flywheels and needed a capacitor in DC.

That tells me the motors are different.

[Martijn Meerts]

Surgery on Dr Yellow was successful.. Installed a Lenz Gold Mini in the motor car (haven't done the end cars yet), and it runs just fine. It seems to run slightly better forwards than backwards, but it's not very noticable. Noise is also a bit worse backwards than forwards, but not by much. The strange noise I mentioned in a different thread (both the Dr Yellow and the Hikari Rail Star made that noise) is gone in the Dr Yellow. Not sure if it's because of the decoder, or because I've oiled/greased it up a bit.

 

Haven't changed any of the settings in the decoder, so it's running completely standard. Been running about half an hour each way now at half speed.

 

Took a bunch of pictures which I will post later.

[Bernard]

Surgery on Dr Yellow was successful.. Installed a Lenz Gold Mini in the motor car (haven't done the end cars yet), and it runs just fine. It seems to run slightly better forwards than backwards, but it's not very noticable. Noise is also a bit worse backwards than forwards, but not by much. The strange noise I mentioned in a different thread (both the Dr Yellow and the Hikari Rail Star made that noise) is gone in the Dr Yellow. Not sure if it's because of the decoder, or because I've oiled/greased it up a bit.

 

Haven't changed any of the settings in the decoder, so it's running completely standard. Been running about half an hour each way now at half speed.

 

Took a bunch of pictures which I will post later.

 

With that successful install, you might be getting a lot of business coming your way so watch out! 

[Martijn Meerts]

Well, the fact that it works with a Lenz Gold Mini doesn't mean it'll work with all other decoders. The Gold Mini's are quite expensive, but they're also of good quality, have tons of features, and have plenty power reserves =)

[alpineaustralia]

My trains also ran quite well.......for a while....and then the nightmare started.

You might recall my post about how Dr Yellow terrorised my local N scale club layout at full speed.

After that the troubles started and not my train only works in one direction.

[Martijn Meerts]

Well, my Dr. Yellow has been running for about 5-6 hours now, including at top speed, minimum speed, both 28 and 128 speed steps. It has also been running as short 3-part base set version as well as full 7-part version, by itself and with other trains running at the same time.

 

It still runs perfectly fine. Some things I did notice though, it's not the smoothest train at low speeds, but I wasn't expecting it to be considering it's a 3-pole motor. At max speed, it runs faster backwards than it does forwards. Backwards the cars started to tilt, and in the curves you could hear the cars hitting the side walls of the elevated track sections. It is awfully fast at max speed =)

 

Also interesting, cars 3 and 5 have a slightly darker shade of yellow compared to the other cars. Strange considering 3, 4, 5 and 6 are cars from the add-on set.

 

 

 

My trains also ran quite well.......for a while....and then the nightmare started.

You might recall my post about how Dr Yellow terrorised my local N scale club layout at full speed.

After that the troubles started and not my train only works in one direction.

 

I've been thinking about this a bit. Do you know how much volts your local N scale club puts on the tracks? There are very few digital systems designed for N-scale (in fact, I can think of only 1, Selectrix, which isn't very popular outside of Germany), and most systems are by default set up for H0.

 

For example, by default my Lenz command station outputs 16 volts with the possibility to set it to anywhere from 12 to 22 volts I believe (some systems can't even be adjusted and just run 16 volts all the time.) If your local N scale club never runs trains at full speed, they might still have their system set to 16 volts. If that's the case, your motor will have gotten the full 16 volts when running at max speed, which could've damaged it.

[CaptOblivious]

I've been thinking about this a bit. Do you know how much volts your local N scale club puts on the tracks? There are very few digital systems designed for N-scale (in fact, I can think of only 1, Selectrix, which isn't very popular outside of Germany), and most systems are by default set up for H0.

 

For example, by default my Lenz command station outputs 16 volts with the possibility to set it to anywhere from 12 to 22 volts I believe (some systems can't even be adjusted and just run 16 volts all the time.) If your local N scale club never runs trains at full speed, they might still have their system set to 16 volts. If that's the case, your motor will have gotten the full 16 volts when running at max speed, which could've damaged it.

 

I don't know what Alpine's club uses, but Digitrax systems have a 12V/16V switch (except the Zephyr—which I'm sure the club isn't using!—which is 12V only).

[alpineaustralia]

That may explain the Dr Yellow problems but not the problems that I have with the series 300.

It is not that my Tomix trains don't run fast, it is that they both start and stops by themselves for no apparent reason on parts of the track that Kato trains just breeze through. They may go days without running and then they will run well (like both are now).

Two additional observations:

 

1. The train is more likely to stop if the rails are not perfectly clean (whereas there is a lot more tolerance with my Katos); and

 

2. Sometime when the trains stop, they sit for a while with a very faint hum, the hum seems to get a little louder (only a little) and then the train will work again.

 

This is why I am convinced the motors are to blame.

[CaptOblivious]

Quick addendum: I just compared the motor cars on my Kato E231-500 and my Tomix 209-0, which have similarly sized motors; both have flywheels. I obtained the following results:

 

Tomix:

Starts: 2.5VDC

Stops: 2.1VDC

 

Kato:

Starts: 3.8VDC

Stops: 2.8VDC

 

Where "starts" means the voltage necessary to get movement from standstill (average over several attempts) and "stops" means the voltage at which the car stops from full-tilt. These numbers are in interesting contrast to Alpine's observations…we'll see what happens when I get a decoder into the Tomix train. Also of interest (and in concordance with Alpine's observations) is that the Tomix motor car runs significantly faster at 12VDC than the Kato car.