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

[Point353]

We try to make our models as backwards-compatible as we can, but it's just not possible to make a state-of-the-art, sound-equipped model from 2018 work reliably with every DC controller ever built from the 1930s to today.

Have you (or your decoder supplier) never heard of a transzorb?
https://www.vishay.com/diodes/protection-tvs-esd/trans-zorb/

[Maletrain]

Put another way, how many model railroaders are going to have a Unitrak loop set up on the kitchen table with a DC pack and DCC ultra equipped locos?  I am surprised at the number here, apparently, and wouldn't fault Rapido for assuming that number was close enough to zero to ignore or dismiss that as an issue.

Hey! I resemble that remark!

Seriously, there are probably a lot of people with Unitrak loops on places like eating tables and shop tables, who are testing newly bought locomotives, even if they have a home layout and/or a club available. In my case, I use an NCE Power Cab for locos with decoders, and an MRC Tech 7 for locos without decoders (that I plan to convert to DCC later).  But I can see guys who have DC-only layouts testing with a DC controller when they get "dual mode" locos, and probably not with their newest controller on that dining room table.  And, those DC folks are buying those high end decoders because that is the only way the nice models they really want are beings sold nowadays.

So, if a company has had problems with its decoders on specific controllers, a warning seems like the responsible thing to do.  And, in the long-run, it will probably help MRC sell more higher-end controllers, anyway.

The real question is how this slid towards "nasty".  I would think that Rapido/ESU and MRC could agree there was a compatibility issue and agree on wording for both companies to publish.  The incompatibility reflects poorly on both products, to some degree, but speaking badly of the other company will reflect badly on both companies across all product lines.

[ljudice]

>>> These guys would never consider charging their iPhone with that transformer

You would be surprised:
 
http://www.nydailynews.com/news/national/iphone-wave-hoax-claims-devices-charged-microwave-article-1.1950755

[Greg Elmassian]

"Put another way, how many model railroaders are going to have a Unitrak loop set up on the kitchen table with a DC pack and DCC ultra equipped locos? "

If the loco is only available DCC equipped, then I would say plenty.

Must be some pretty nasty spikes to crash a quality decoder. Sure would be nice to know at what voltage the spike kills the decoder.

Greg

[peteski]

Have you (or your decoder supplier) never heard of a transzorb?
https://www.vishay.com/diodes/protection-tvs-esd/trans-zorb/

The problem is with size. Decoders are already tightly packed with components and you want to add another one?  ESU already uses what looks like a Zener diode at the output of the rectifier to clamp any excessive voltage.   Remember this?



The also use very low forward voltage rectifier diodes - those  might be sensitive to excessive voltages.  It would be interesting to know which components get damaged by the 1300 throttle.

I don't know what ESU specs are but I suspect that they are rated up to 20 or 25 Volts.  SO how far do you go to go out of your  way to make a decoder  robust enough to withstand higher voltages?  Again, if there is enough real estate on the decoder (for larger scales like H0 or 0) then sure, put all the over-voltage protection that you can. But I don't think this is realistic in smaller scales decoders.

What puzzles me is that we don't hear more about other models of ESU decoders being fried by the 1300. After all, they are used in many more models. Companies like IM and Atlas use them.  Then many modelers custom-install them in their models, but I suspect that this group only uses them on DCC.

[Point353]

The problem is with size. Decoders are already tightly packed with components and you want to add another one?  ESU already uses what looks like a Zener diode at the output of the rectifier to clamp any excessive voltage.   Remember this?



The also use very low forward voltage rectifier diodes - those  might be sensitive to excessive voltages.  It would be interesting to know which components get damaged by the 1300 throttle.

I don't know what ESU specs are but I suspect that they are rated up to 20 or 25 Volts.  SO how far do you go to go out of your  way to make a decoder  robust enough to withstand higher voltages?  Again, if there is enough real estate on the decoder (for larger scales like H0 or 0) then sure, put all the over-voltage protection that you can. But I don't think this is realistic in smaller scales decoders.

What puzzles me is that we don't hear more about other models of ESU decoders being fried by the 1300. After all, they are used in many more models. Companies like IM and Atlas use them.  Then many modelers custom-install them in their models, but I suspect that this group only uses them on DCC.

The transzorb could possibly replace the zener, so the component count wouldn't necessarily have to be increased.
However, without knowing exactly what parts are failing, the best that can be done is to speculate.

It doesn't seem as though it would be impossible to make the decoder immune to whatever "spikes" the MRC pack is alleged to be generating. The problem was related to the decoder in an HO/H0 RDC, so limited pc board space is unlikely to be a constraint.

Unlike Rapido, IM and Atlas typically make their locos available both with and without decoders, so there may be far fewer IM and Atlas decoder-equipped locos being run in "DC compatible" mode.

[thomasjmdavis]

It strikes me that if 1300s are common (they are) and if they often produce voltage spikes (I will accept Jason's report that at least 100 of their decoder equipped locos failed when powered with 1300s), it should not be too awfully difficult or expensive to develop a circuit to use on a 1300 between the pack and the track that would provide voltage regulation (perhaps not the right word, my last electronics class was prior to the first moon landing) or limit to prevent spikes from damaging equipment.  While a DC motor might not suffer much from a voltage spike of short duration, it would be shortening the life of lighting and other track powered circuits on locos and cars- so there would be a benefit even for DC only users.

"Put another way, how many model railroaders are going to have a Unitrak loop set up on the kitchen table with a DC pack and DCC ultra equipped locos? "

If the loco is only available DCC equipped, then I would say plenty.

Judging from commentary over the years, there are quite a number of modelers who are members of clubs with very sophisticated DCC systems, but the one they have at home is an HO 4x8 or an N scale hollow core door, or a shelf with a switching layout.  Probably only run 1 train at a time.  While DCC might be cool to have, house payments, car payments, medical expenses and putting kids through college all come first- they stick with the DC power pack.  So they save up, buy that fancy sound equipped locomotive primarily to run on the club layout, but still want to run it on the small layout at home.  No doubt, there are some that are the other way around- the home layout has DCC, but the club layout is still getting by on DC and walkaround throttles, or some such.

[peteski]

The transzorb could possibly replace the zener, so the component count wouldn't necessarily have to be increased.
However, without knowing exactly what parts are failing, the best that can be done is to speculate.

I agree. I also should have also mentioned that parallel with the Zener diode is a small value ceramic cap. As I understand that circuit, that cap is there to shunt sharp voltage spikes.  But without having more specific  info about the throttle and which components fail, we are speculating.

The components you mentioned are fairly large (physically) which is a problem on small decoders.  Maybe there is a smaller version of those available elsewhere.

[Doug G.]

Thanks for the explanation, Jason.

Doug.

[rapidotrains]

Unlike Rapido, IM and Atlas typically make their locos available both with and without decoders, so there may be far fewer IM and Atlas decoder-equipped locos being run in "DC compatible" mode.

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

-Jason

[learmoia]

In True Railwire fashion, we are putting way too much thought into this..

Frankly I'm amazed that the total group of modelers that:
- Are Running Sound without DCC (large group I know)
- and will pony up the money for a DCC/Sound Rapido locomotive. (Medium-Large group)
- But insist on running those trains on a cheep  a$$ 50 year old power pack.

Is 100 people..

Wait... nevermind..... 

~Ian

[mmagliaro]

Given that MRC has made lots of packs that have some pretty darn harsh pulses in the output (the 2400 and 2500 come to mind), I'm surprised that the 1300 is the one that stands out in Rapido's experience for decoder damage.  I'm not doubting them.  I'm just surprised.  Because I can't imagine that the 1300's pulses would be that much different, or of higher amplitude, than their other products.

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.

Makes me wish I still had my oscilloscope (ditched it a few years ago because I never used it anymore).  I'd love to take a 1300 apart to see what's inside, and then scope the output.

I think that MRC should be doing this for the sake of good customer relations.   And if I were Rapido, I'd want to do this
out of scientific curiosity.  No, they are not responsible for MRC's products.  But it's become a problem that is causing
bad blood between the two companies.  The best way to combat that is with science and evidence rather than arguing.

[up1950s]

I would bet my last Canadian cent that Jason has a scope and a scope operator which has scoped this out . I have a 2400 , a small scope ,  but no Rapido locos . I am not an a reliable scope-a-cetic set up guy like Pete and others though . I would like to know if these spikes can be read on a no load XT output , or do you need to run a loco . Also , if so does it need to be synced and to what on the board ? We need a sparky to prove this and teach the masses here .

[brokemoto]

(Attachment Link) I have an old MRC Tech 1400 power pack as well that I occasionally use to break in locomotives

I was never happy with running decoder equiped  loco's on DC . so I don't ..  while technically decoders support DC mode, doesn't make it a good idea .. if you are going to spend a lot of money to decoderize, then run them that way ..

You mean 2400.  That is the one that I like the best, as you can turn OFF the pulse.

I ain't exactly none too crazy about doin' it, neither, but there are times when you do not have much choice.  The B-mann ten wheeler, mogul, industrial switchers, EM-1 and doodlebug come only one way:  with a decoder (there is a trainset version of the ten wheeler that is an exception, but, other than that.................).

BLI products come only with the decoder.  While the MRC/MP "decoder ready" version of the  eight wheeler and mogul show available, I do not see any of the
e-Tailers that have good prices that have them available.  These same e-Tailers have the DCC/sound versions available.  The MRC site shows the non decoder versions available, but, at full list price.  I am not paying full list price.

I will not put a decoder into a locomotive, but, there are times when I want the locomotive but do not get the choice of decoder or  no.

[brokemoto]

Frankly I'm amazed that the total group of modelers that:
- Are Running Sound without DCC (large group I know)
- and will pony up the money for a DCC/Sound Rapido locomotive. (Medium-Large group)
- But insist on running those trains on a cheep  a$$ 50 year old power pack.

In some cases, the only way that we can have the locomotive is to have it with the decoder and the sound.  The manufacturer does not sell it in any other configuration.  This is the case with the BLI Baldwin Centipede.  It comes only with sound and a decoder.

I would call the cube B-mann and MP power supplies "cheap and old".  I would call an old Varney trainset power pack "cheap and old" (yes, I have one--one of the last generation.  It has a plastic casing).   I do not use any of the cheap packs to operate locomotives.  I do use the B-mann trainset power supply to operate the
E-ZTRAK switch machines.  I will use the MP or B-mann cube shaped power supplies to power accessories or to supply power to a locomotive that is upside down in a servicing cradle.

If I am selling at a show, I bring a test track with an eleven inch loop.  Often I will bring a MRC 2400, but, at times, I forget it and am stuck with the B-mann or MP.  That thing is passable for a test track.

Never would I operate a layout with one.