Now This Is Weird - A Major MRR Supplier Dissin' Another on Their Website

[jagged ben]

Rapido's statements about the older motors aren't exactly crystal clear.
I interpreted the video to mean that all of the motors from the previous supplier were "weak" - either for N or HO locos.

In the absence of more specific technical details regarding this matter from either Rapido nor ESU, I'm speculating that the "weak" motors might be drawing more current and or require a higher applied voltage for a given speed and load, which then might be overstressing the decoder to the point of failure.
If the decoders are protected from overload and, as you suggest, a "DC power pack should not produce a voltage high enough to damage or stress a decoder", then we're back to square one.
...

I have to say that I find this plausible enough that it shouldn't be dismissed out of hand.   On the other hand, the information regarding which motors were used in which models is vague enough that it remains a very speculative hypothesis.   Moreover, the CVs they tell you to change in the video have something to do with BEMF speed stabilization, and this is probably a more relevant clue to what's going on.

[peteski]

Ah, what we have is a typical "Internet and social media thing"  Someone floats some more-or-less plausible idea, then all the so called "experts" start chiming in, and pretty soon we have a connection of unconnected facts.

@rapidotrains is also not helping things by not providing some more (technical) details about the problem. I'm talking about the ESU decoders and MRC 1300 power packs.  As I and Max mentioned it in our "expert" opinions, the decoder damage problem and weak motor problem are totally separate.  But what the heck - lets all speculate that this is a Rapido conspiracy! 

[greenwizard88]

Seems like Walthers is also hating on the MRC 1300 series power packs now.

https://www.modeltrainstuff.com/walthers-mainline-ho-910-20420-emd-gp9-phase-ii-with-chopped-nose-conrail-7565-esu-sound-and-dcc-equipped/

PLEASE NOTE: When operating Walthers-branded DCC-equipped locomotives in DC mode, do not use power packs that exceed an 18V rating. This includes MRC 1300-series power packs which have known issues with our decoders.

[peteski]

Seems like Walthers is also hating on the MRC 1300 series power packs now.

https://www.modeltrainstuff.com/walthers-mainline-ho-910-20420-emd-gp9-phase-ii-with-chopped-nose-conrail-7565-esu-sound-and-dcc-equipped/

Well, this clearly shows that it is neither Rapido, nor Walthers - it is ESU.  Too bad we don't 'have any ESU representation here to comment on their decoder's maximum voltage rating.  I participate in the ESU LokSound group (on Yahoo groups, and now on groups.io),and I don't recall anybody bringing up this problem. But then again, that group is geared towards users runing them on DCC (not DC).

[mmagliaro]

I disagree.  I do not read from the Walthers warning that it is ESU's fault.  In fact, the warning says,
"in DC mode, do not use power packs that exceed an 18V rating. This includes the MRC 1300-series powerpacks"

They are mentioning MRC, fair enough, but they are mentioning a specific voltage limit which they believe is the problem.

Maybe... they looked at power pack outputs and found that packs rated at 18v are likely to have rectified DC peaks above 25 volts.
Maybe they saw all the discussion and oscilloscope posts on this forum, and are at least convinced that high voltages like that
are a bad idea and are not worth taking a risk on, even if they are technically within the NMRA specs.

Maybe, maybe, maybe..... egad.

There is a "review/comment" section on MRC's website under each product, and I posted some info about what I found, and asked some questions about the product: specifically about Rapido's claim against MRC, the 25 volt peaks, and why the facts that they are UL listed and have been making the 1300 for 25 years has anything to do with this problem.  Not only did I get no reply, my post was deleted in a day.

I do agree with Peteski on one thing: the "typical "Internet and social media thing".
The fact that MRC, Walthers, and Rapido have been so silent about any data they have to back up their various claims is only making this problem worse.  It's like they are all more interested in blaming somebody instead of testing, getting solid data, and sharing it with each other and their customers.

[peteski]

I disagree.  I do not read from the Walthers warning that it is ESU's fault.  In fact, the warning says,
"in DC mode, do not use power packs that exceed an 18V rating. This includes the MRC 1300-series powerpacks"

Max, neither Rapido or Walthers are specifically pointing the finger at ESU, but it is ESU that designed, produced and supplied the DCC decoder to Rapido and Walthers. I'm quite sure it is a standard ESU design (maybe on a redesigned PC board).  So it is ESU's (not Rapido's or Walthers') hardware that supposedly smokes on high enough DC power pack voltage. We should really be asking ESU for an explanation.

[Point353]

We should really be asking ESU for an explanation.

Already tried that using using the contact form on the ESU website, but have yet to receive any response.
http://www.esu.eu/nc/en/contact/email/

My next step would be to call them.
http://www.esu.eu/en/contact/

[thomasjmdavis]

From the Lok Sound 5 manual p. 7-

•Any power supply must be protected by a fuse or circuit breaker
to avoid any potential hazards such as burning cables in case of
a short circuit. Only use transformers specifically designed for
model trains that bear the VDE/EN marks.

[jagged ben]

Guys, read the NMRA standard here:
https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-9.1_electrical_standards_2006.pdf

It reads in part:

...Digital Decoders intended for scales larger than "N" shall be designed to withstand a DC voltage of at least 27 volts as measured at the track. ...

So...if Walthers is now saying that the decoders can't withstand more than 18V...then...

ESU has released a decoder that doesn't meet NMRA standard. 

Now that isn't a crime, but ESU should have said so, or at least stated a max DC voltage clearly somewhere in the documentation.  And to be fair to ESU, every other DCC manufacturer so far as I've noticed is equally guilty of not specifying a max voltage.  I find that to be a travesty by the way... In what other industry do manufacturers release electronic parts where the user is expected to apply a raw voltage to the device from any source they please, but they don't specify or remind the user of the max voltage in the product documentation?    Note that the NMRA standards do not even specify a max voltage for DC track power!  So all DCC decoder manufacturers should be stating max DC voltages for every decoder that supports analog mode and so far as I've noticed none of them do, so that's problem #1.

Now let's go back to the MRC powerpack...
Max tested it and found peak waveform voltages of 25V but an RMS voltage of below the nameplate 15V.  So unless someone can show that their quality control isn't keeping the voltage there, none of this is really their fault.  After all, the decoder per NMRA standard is supposed to withstand more than 25V RMS.  I don't know why the Railpower 1300 should be getting the call out but in my opinion it's moot if no one can show that the RMS voltage is more than nameplate.

[thomasjmdavis]

My interest in this is mostly so that I can talk it over with my son, who is an electrical engineer who works on control systems for robotics (which is to say, I don't have a 1300, and my old rheostat packs went into the trash after being damaged years ago).  So I went and looked up the specs on the Railpower 1300.  I want to ask him intelligent questions, so are any of these relevant-

The power output is specified in the documentation as 7VA.  Would that not mean that at 15volts, the amperage would be .4667?  I am left wondering whether the power pack is not underpowered (for HO if not for N) for a sound equipped locomotive (the equivalent of trying to run O scale locomotives with an HO train set power pack). 

And the pack has some sort of (electronic?) circuit protection, but it reads in the documentation more like thermal protection- that is, circuit is broken when the components of the power pack overheat, and is restored after they cool off, rather than circuit breaking as a result of a voltage spike or amperage draw per se (that is, it does not trip until the pack itself overheats).  Could that be "too long" for the more delicate circuitry of the decoder?

And in defense of N scale locomotives over the past 50 years- if the NMRA allows a nominal 12volt power pack to output  27 volts, it would certainly explain why some locomotives run at 275 scale MPH when on "full".

[Maletrain]

I remember reading somewhere several years ago that somebody's decoders should not be exposed to more than 16 volts.  That got me to buy an NCE PowerCab, because my Bachmann simple DCC controller was putting out 18 volts.  Too long ago to remember who was saying not to exceed 16 volts, but it was a decoder manufacturer, if I am remembering correctly.  I saw it because I was contemplating adding sound to a Bachmann loco.

[Mark5]

Been watching this thread off and on (needs popcorn!  )

Maybe Maletrain was looking at a Soundtraxx decoder:

Operating your DSD-LC at voltages greater than 16 volts will void your
warranty, produce excessive heat and possible permanent damage to
the DSD.

https://soundtraxx.com/content/Reference/Manuals/LC/lc_manual.pdf

Mark

[peteski]

My interest in this is mostly so that I can talk it over with my son, who is an electrical engineer who works on control systems for robotics (which is to say, I don't have a 1300, and my old rheostat packs went into the trash after being damaged years ago).  So I went and looked up the specs on the Railpower 1300.  I want to ask him intelligent questions, so are any of these relevant-

The power output is specified in the documentation as 7VA.  Would that not mean that at 15volts, the amperage would be .4667?  I am left wondering whether the power pack is not underpowered (for HO if not for N) for a sound equipped locomotive (the equivalent of trying to run O scale locomotives with an HO train set power pack). 

Volt/Amps rating is in fact rating of power rating for AC (it is similar to Watts power rating but for AC power). See https://en.wikipedia.org/wiki/Volt-ampere.
Half an amp is sufficient for N scale sound decoders, but even if too much current was being drawn out of it, the voltage would go down (not up).

And if you want to present your son with some serious technical analysis of that power pack (including its schematic), see https://www.therailwire.net/forum/index.php?topic=44170.0. Max even purchased an oscilloscope to analyze the output of that throttle.  Thread is long, but worth reading (skipping the chaff of course). 

[thomasjmdavis]

Surely you mean VA is the rating for DC (not AC) power.  Watts is the common rating for AC, as shown (in kilowatts) on my electric bill.

[peteski]

Surely you mean VA is the rating for DC (not AC) power.  Watts is the common rating for AC, as shown (in kilowatts) on my electric bill.

No, read the link I posted earlier.
Here is an excerpt:
A volt-ampere (VA) is the unit used for the apparent power in an electrical circuit. The apparent power equals the product of root-mean-square (RMS) voltage and RMS current. In direct current (DC) circuits, this product is equal to the real power (active power) in watts. Volt-amperes are useful only in the context of alternating current (AC) circuits.

If a manufacturer states power rating for some AC device in Watts, then they already did the conversion from VA to Watts.