# Tsunami 2 Overload in Bachmann Mallet



## Fern Creek & Western (Mar 15, 2016)

Hello all,
I recently installed a 4 amp Tsunami 2 sound decoder in my Bachmann 2-6-6-2T Mallet. The model uses a 14.8v Lithium-Ion battery and an Airwire 6 Amp receiver. All that works fine and the model runs great...until it hits a grade. The engine stalls and the locomotive lights all flash, indicating a motor overload. The model has 2 fairly large motors in it, but I figured a 4 amp decoder could handle that. Apparently it can't. I'm wondering if anyone has any ideas as to how I can solve this issue. I really like the Tsunami 2 and want to find a way to make it work with the engine.

Thank You in advance,
Trevor


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## LGB333$$$$ (Oct 11, 2017)

Wonder if your battery is providing enough volts? If you don't get a solution from this Forum, suggest you contact Soundtraxx' Support Dept: [email protected] They're very responsive. I asked them a question this morning about the CV programming to keep the loco's headlight on in reverse direction......the Tsunami2 guides didn't cover it and they responded with the procedure.

By the way, I can't program any of the Tsunami2 decoders I recently bought using my Massoth Central Station and Dimax Navigator, even after I bought and tried using their PTB-100 Programming Track Booster. So sent Soundtraxx Support Dept an email today asking for help. This is odd since I can change the CVs on the Bachmann large scale locos with the factory installed sound systems, which are also made by Soundtraxx. So something is wierd with the Tsunami2 decoders.


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## Fern Creek & Western (Mar 15, 2016)

Yeah I was thinking about upping the volts. Given that the Tsunami 2 can handle up to 21 volts and the AirWire Converter 6 amp can handle 22, I'd say 18 volts would be safe. I am going to supply the engine 18 volts from an external power supply and see what that does and report back.

The current fix right now is that I actually removed one of the motors and now the front engine set rolls free. One motor does not overload the Tsunami, but now the thing does not pull all that well. Hopefully more volts will remedy the problem.

Trevor


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## LGB333$$$$ (Oct 11, 2017)

The Tsunami2 TSU-4400's specifications should handle your two motors that probably don't draw more than below:
Motor Stall Current - 4A Maximum;
DCC Track Voltage - 7.5V - 26V.
Tom


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## East Broad Top (Dec 29, 2007)

Can you test the current draw of each motor individually? The 2-6-6-2 uses a Mabuchi motor, and I've seen those go bad, with one drawing a lot more current than the other. Typically that manifests itself in one motor running slower than the other as well, but you're not going to see that if the loco is always running on the rails. Failing that, check with Soundtraxx with your overload issues. You should be able to drive 2 Bachmann motors without trouble. I vaguely recall a conversation with Soundtraxx about that rating where they suggested it was somewhat conservative. I used to own a 2-6-6-2; its average current draw (based on battery life) was between 3/4 and 1 amp depending on whether I was doing a lot of switching or not. 

One thing to consider: The old Tsunami decoders were rated at 1 amp. There was a company who was modifying them for O scale, giving them a 3-amp rating. Their change? Wrapping a heat sink around the decoder. That was it. The current overload trigger on them apparently wasn't something that was actually measuring the current coming through the board, since the "modified" boards were good for three times the current. I haven't a clue if the Tsunami2s are the same way, but given the possibility of a bit of headroom in the rating, I would suspect something similar to be the case. 

Later,

K


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## Fern Creek & Western (Mar 15, 2016)

My temporary solution was actually to remove one of the motors and run the engine with only 1 motor. It does run without overloading now, but the pulling power is somewhat pathetic now. So maybe I can measure the draw from one motor at a time. I will try to give Soundtraxx a call and ask about the heat sink. The decoder definitely gets hot when it overloads, so maybe that'll mediate the problem.

Trevor


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## placitassteam (Jan 2, 2008)

Greg, You look pretty good for not being here! I kind of miss your feistiness.


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## Dan Pierce (Jan 2, 2008)

When looking at specs, Zimo gives us the raated average current max and they also give the surge current which can last 10 seconds or more. So the 6 amp decoder will sustain a 10 amp surge. Not all manufacturers give this type of data. Zimo also does this with voltage specs.


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## krs (Feb 29, 2008)

LGB333$$$$ said:


> The Tsunami2 TSU-4400's specifications should handle your two motors that probably don't draw more than below:
> Motor Stall Current - 4A Maximum;
> DCC Track Voltage - 7.5V - 26V.
> Tom


Tom,
As I pointed out in another thread, no other Large Scale DCC manufacturer uses *stall current* as their main current spec.
A stall current of 4 amps means that the continuous current spec is around 1.5 amps or so. Strangely enough, I could not find an actual continuous current spec for the Tsunami 2.
When you compare decoders from different manufacturers, keep that in mind.


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## AALLSTAR (Mar 28, 2021)

krs said:


> Tom,
> As I pointed out in another thread, no other Large Scale DCC manufacturer uses *stall current* as their main current spec.
> A stall current of 4 amps means that the continuous current spec is around 1.5 amps or so. Strangely enough, I could not find an actual continuous current spec for the Tsunami 2.
> When you compare decoders from different manufacturers, keep that in mind.


I use a few Econami Decoders rated at 2A on my O Gauge layout and a few loco's trip at 1A however this is not the peak current under load especially at start up. I have one USA loco in particular that would stall when pulling itself never mind a load. Eventually I replaced the motor with a higher voltage less current type which fixed it. Soundtraxx offered no solutions as the Decoder was operating within spec. Its the peak motor current that causes the trip 12 flashes. If only the sensing circuit had a built in delay this I feel would solve the issue. I'm now considering upgrading to the Tsunami2 as should be well within the current trip limits. My loco's are fitted with Mabuchi 24v motors which on average pull 250ma at 20v with no load and the stall current is around 1.5A.


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## Greg Elmassian (Jan 3, 2008)

get a different decoder, this policy of advertising the decoder as 4 amp, when it can only handle 4 amps for a very brief instant is just baloney.

Decoders should be speced with max continuous load and "stall current", but stall current without a duration in time is really not helpful.

The stall rating should be double to quadruple the continuous load when not fully specified with a duration.

Also, Tsunamis will also "overcurrent" much more easily when the voltage approaches 21 volts, which means they do not meet NMRA G scale requirements for max DCC voltage.

I've been in the large scale hobby for over 20 years, and this "design policy" of SoundTraxx has never improved.

I have a tiny rail truck that would overvoltage/overcurrent with a Tsunami, it runs on a fraction of an amp. Substituted an HO Zimo decoder, all problems went away.

Greg


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## LGB333$$$$ (Oct 11, 2017)

AALLSTAR said:


> I use a few Econami Decoders rated at 2A on my O Gauge layout and a few loco's trip at 1A however this is not the peak current under load especially at start up. I have one USA loco in particular that would stall when pulling itself never mind a load. Eventually I replaced the motor with a higher voltage less current type which fixed it. Soundtraxx offered no solutions as the Decoder was operating within spec. Its the peak motor current that causes the trip 12 flashes. If only the sensing circuit had a built in delay this I feel would solve the issue. I'm now considering upgrading to the Tsunami2 as should be well within the current trip limits. My loco's are fitted with Mabuchi 24v motors which on average pull 250ma at 20v with no load and the stall current is around 1.5A.


If you want to continue to use the Soundtraxx Tsunmai2 sound decoders, which have excllent quality sound, you should use their 4400 series decoders which are the 4 amps (stall current) capacity. I've installed several of the 4400 units in one motor LGB locomotives and experienced no problems with overloading them. But their capacity isn't apparently suitable for two motor locomotives. For that, you'd need to use a DCC driving/function decoder for the other motor, which isn't ideal, so as Greg indicates, use a different brand decoder such as the ones I also install and sell, such as the Massoth XLS Sound Decoder or the ESU 5XL Sound Decoder, both rated at 4 amps for one or two motor LGB locomotives.


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## AALLSTAR (Mar 28, 2021)

LGB333$$$$ said:


> If you want to continue to use the Soundtraxx Tsunmai2 sound decoders, which have excllent quality sound, you should use their 4400 series decoders which are the 4 amps (stall current) capacity. I've installed several of the 4400 units in one motor LGB locomotives and experienced no problems with overloading them. But their capacity isn't apparently suitable for two motor locomotives. For that, you'd need to use a DCC driving/function decoder for the other motor, which isn't ideal, so as Greg indicates, use a different brand decoder such as the ones I also install and sell, such as the Massoth XLS Sound Decoder or the ESU 5XL Sound Decoder, both rated at 4 amps for one or two motor LGB locomotives.


One solution I found was to add a simple motor amplifier circuit fed directly via the output of either the Econami or Tsunami Decoders however you lose motor feedback which I have not looked into yet but the one loco I have fitted this to no longer stalls + the output can shunt over 4A all subject to the characteristics of the output transistors & heat sinking.


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## Greg Elmassian (Jan 3, 2008)

Yeah, unfortunately, no longer passing the BEMF signal kills one of the big advantages of the SoundTraxx, to use BEMF to change motor sounds by load, and also the smoother running of motors with BEMF.

This has been an issue with SoundTraxx for years (note this thread started 4 years ago), not rating their decoder capacity in terms users can use, a 4 amp decoder should be able to handle 4 amps continuously, not for just a fraction of a second.

Greg


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## Dan Pierce (Jan 2, 2008)

I use Zimo and the output current is 6 amps for several decoders and is spec'd for 10 amp surge plus no heat sink required. Zimo also has a 4 amp decoder with a surge current spec. THese also have voltage surge specs at least 30 volts. Most MFG's do not publish these specs but Zimo does.


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## East Broad Top (Dec 29, 2007)

I know this is an old thread (4 years, now) but Soundtraxx just updated the firmware on their 4-amp boards to address issues connected to faulty high-current overload detection. I had four boards I bought around 18 months ago that all triggered at ridiculously low current. Just in the past few months, Soundtraxx revamped the firmware and made some other minor changes. They had known about the issue for a while, but lacked the manpower to address it right away. They replaced my four boards and now all four locos are happy and do not trigger any overloads. New production boards are shipping with these changes incorporated into them.

Later,

K


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## Greg Elmassian (Jan 3, 2008)

That is great news, since the decoders normally would go into overload if you just looked at them funny.

But, as far as I know, you cannot update the firmware on these boards, replace only.

So, does Soundtraxx say they will do this for anyone with the problem? Did you ask?

Greg


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## East Broad Top (Dec 29, 2007)

I asked in reference to the four boards I had purchased which were definitely faulty. I know others had similar issues with boards purchased around the same time which were likewise addressed by Soundtraxx. I cannot speak to older 4-amp boards, as my older boards 4-amp boards worked just fine (which is why I knew the ones I had ST replace were definitely out of the norm). If you have a board that's tripping prematurely, I'd suggest contacting ST and asking them. Note that in my case, it was a firmware and component upgrade, so it was easier for them to just ship new boards than replace the components on mine. I had two of my locos which got these new boards out running at a friend's place yesterday, and both performed well.

Later,

K


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## Dan Pierce (Jan 2, 2008)

Some older soundtraxx boards had a limit of 22 volts and tripped on my DCC track as I have 24 volts on the track ( Zimo MX1 and MX10 use 30 volts input to get 24 volts to the tracks). NMRA specs call for 27 volts DC and 22 volts DCC, so the units are not considered as 'bad'.


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## Greg Elmassian (Jan 3, 2008)

I have several friends with the original "Quasinami" stock in thier shay from Bachmann, and give it 21 volts or so and "overload"... glad to see that seems to have been fixed.. I had the same issue since I run my layout to NMRA standards also, and got rid of my early Tsunamis, the HO versions did the same thing too, no Zimo also. The QSI will handle 47 volts believe it or not! (to accomodate wild top voltages from early Bridgewerks and toy train type running).

Unfortunately there are locos that are geared so low you cannot achieve prototype speeds without going to 24v to the rails (or input to the decoder). (3 axle Aristo diesels are a good example). (Kevin I know you don't run this on your home layout of course)

Also, remember people trying to run geared locos too fast with something like a Bridgewerks, it's easy to overload the input voltage of a Tsunami. (of course a Bachmann shay runs prototype speed at easily within the Tsunami voltage  )

Just good stuff to be aware with when you use G scale decoders that are NOT NMRA compliant.

Greg


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