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

[peteski]

So let's separate the two terms clearly: "pulses" and "spikes".
Is it really the pulses in the 1300's DC output that are causing this OR is there some sort of turn-on or turn-off spike that goes out whenever the pack is switched on/off or the direction switch is flipped?   Or is there a flaw in the circuit such that a one-off spike can go out when changing speeds if the speed control pot loses contact for an instant.

That is exactly what I was harping about earlier.  Spikes are usually harmless to DC locos but can mess up delicate decoder electronics.
But at the same time I also think we should put this thing to rest.  Without specific numbers this discussion is getting pointless.

[Point353]

We offer DC-only on just about all of our models.

-Jason

Was the HO TurboTrain available DC-only?

[mmagliaro]

That is exactly what I was harping about earlier.  Spikes are usually harmless to DC locos but can mess up delicate decoder electronics.
But at the same time I also think we should put this thing to rest.  Without specific numbers this discussion is getting pointless.

Yes.  I was hoping somebody with a scope and these packs would chime in here.

Sigh... time to start trolling eBay for a good used Tektronix scope again....

[rapidotrains]

Was the HO TurboTrain available DC-only?

No, but it is questionable whether you could call it a powered model because it ran so badly. 

-Jason

[mmagliaro]

Okay, my scientific curiosity got the better of me (as it always does).

The oscilliscope is on the way.   After it arrives, I'll poll the populace to see if anyone would be willing to donate a Railpower 1300
to my evil laboratory to test it. I will not destroy it.  I just want to run some trains with it and scope the outputs to see what the heck it does AND I will want to drill out the case rivets, open it up, draw out what the circuit is, and then put it back together with screws.

Yes, this will completely void any warranty, so be aware of that if anyone volunteers to send me one for dissection.

Jason,
Rapido Trains will be welcome to whatever I discover about this power pack after I do this (in the event that you don't already know everything there is to know about it and are keeping mum out of professional courtesy to MRC).

[peteski]

Okay, my scientific curiosity got the better of me (as it always does).

Very good!  I have couple of oscilloscopes (old Tektronix 465 and a newer Rigol digital storage scope), but there is no way I was going to take on another project at this point.   

[Point353]

So, was the Rapido decoder problem really due to some sort of  incompatibility issue with an MRC powerpack or was it a fault of the inferior quality motors that Rapido has been using?

[peteski]

I thought we were discussing Rapido's assertion that the MRC 1300 DC power packs had a track voltage too high, and were blowing up their (ESU-branded) factory installed decoders.  Nothing to do with motors (which seems like a different QC problem on its own).

I only watched part of the video since it seems to deal with motors in H0 scale models. If the MRC 1300 and blown decoders is mentioned later on in the video - I apologize.

[Rich_S]

I thought we were discussing Rapido's assertion that the MRC 1300 DC power packs had a track voltage too high, and were blowing up their (ESU-branded) factory installed decoders.  Nothing to do with motors (which seems like a different QC problem on its own).

I only watched part of the video since it seems to deal with motors in H0 scale models. If the MRC 1300 and blown decoders is mentioned later on in the video - I apologize.

Hi Pete, The way I understand the problem, Rapido is stating from experience (numerous returns of Rapido customers using the MRC 1300 power pack) there is an issue specifically with the MRC 1300 transformer / power pack. If you look closely at the video posted by Point353, Rapido has been using the MRC Tech 3 Model 9500 transformer / power pack without issues.  Rapido is not saying all MRC transformers / power packs have issues, only the MRC 1300 transformer / power pack.

The question that has not been answered by MRC, what specifically is the difference between the MRC 1300 and the MRC 1500 or the MRC Tech 3 9500 transformers / power packs?  The MRC Tech II 1500 and the MRC Tech 3 9500 do not appear to have the problem of the MRC 1300.  Naturally MRC is going to take the stance that they've been manufacturing power packs since the dawn of time and nothing could ever be wrong with any of their power packs. But when you have a large percentage of your customers returning products and the only thing in common is the power pack being used, something is incompatible between the two. In a nutshell, all Rapido is telling their customers is switch to another MRC power pack before having the locomotive repaired. Now my personal disclaimer, I've been using MRC transformers / power packs since 1968 without any issues and in my opinion they are a sound and solid company, but there does seem to be some kind of compatibility issue between the MRC 1300 and some of Rapido products. These same Rapido products do not have an issue with other MRC transformers / power packs, so the question still is, what is different with the MRC 1300?   

Lastly Pete, from my understanding you are correct, the MRC 1300 issue has nothing to do with the motor issue in the Rapido RS-18.

[u18b]

I think Max did a thorough hi-tech wave oscilloscope analysis of this in another thread.

[Point353]

I thought we were discussing Rapido's assertion that the MRC 1300 DC power packs had a track voltage too high, and were blowing up their (ESU-branded) factory installed decoders.  Nothing to do with motors (which seems like a different QC problem on its own).
I only watched part of the video since it seems to deal with motors in H0 scale models. If the MRC 1300 and blown decoders is mentioned later on in the video - I apologize.

Rapido mentions in the video that the older motors were "weak".
Could those motors therefore have been drawing relatively more current and/or required a higher voltage level (but still within the NMRA standards for a decoder), the combination of which might have then over-stressed the decoders and caused them to fail?

[peteski]

Rapido mentions in the video that the older motors were "weak".
Could those motors therefore have been drawing relatively more current and/or required a higher voltage level (but still within the NMRA standards for a decoder), the combination of which might have then over-stressed the decoders and caused them to fail?

I'm still confused.  I thought those week motors were not performing well. What you are implying is that they were damaging the decoders?  I believe that ESU decoders have a protection built-into the motor circuit, and maybe even a thermal protection in cases the decoder overheats.  Besides, even at maximum track voltage, a DC power pack should not produce a voltage high enough to damage or stress a decoder.

Also, the weak motors were in H0 scale models, while the blown decoders (supposedly due to something that MRC 1300 power pack is to blame for) occurred in both N scale, and H0 scale models?

And yes, there was a lenghty tread about the decoder problem with excellent analysis of the MRC 1300 power pack done by Max Magliaro.

[Point353]

I'm still confused.  I thought those week motors were not performing well. What you are implying is that they were damaging the decoders?  I believe that ESU decoders have a protection built-into the motor circuit, and maybe even a thermal protection in cases the decoder overheats.  Besides, even at maximum track voltage, a DC power pack should not produce a voltage high enough to damage or stress a decoder.

Also, the weak motors were in H0 scale models, while the blown decoders (supposedly due to something that MRC 1300 power pack is to blame for) occurred in both N scale, and H0 scale models?

And yes, there was a lenghty tread about the decoder problem with excellent analysis of the MRC 1300 power pack done by Max Magliaro.

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 a few of these decoder-equipped Rapido locos I'd like to run on DC without worrying about the type of powerpack.
Neither Rapido nor ESU have responded to my inquiries for further info.
I'm not sure what else to do to in an attempt to resolve this matter.

[mmagliaro]

My previous analysis of the 1300, complete with oscilloscope shots and circuit mods, is here:
https://www.therailwire.net/forum/index.php?topic=44170.60

This had nothing to do with motors.  It was all about decoders blowing up, and Rapido experiencing a higher than normal decoder failure rate when using the MRC 1300. 

My tests and scope plots, along with very helpful contributions from Metalworkertom and Peteski, show that the 1300 appears to be the only pack that has 25 volt peaks in its output.  The others, like the 2800, have peaks that don't break 20 volts.  I still think that this is the root of the problem.

As to whether a "weak" motor could cause a decoder to fail, because the motor characteristics cause it to draw more current from the decoder than it should, I don't think that is a relevant point.  Even if that were true, there is no reason to expect that the power pack would have anything to do with this.  The decoder failures at Rapido were not in any way limited to the RS-18, which is the engine they explained had the bad motors.

[MetroRedLine]

Can't resist...