Protecting DCC Decoders From Killer Shorts (281)

Well the video last week opened the flood gates with questions and comments on the subject of shorts and what can be done about them. Consequently I decided I needed to address those questions and comments and provide some more information in this followup video. I mentioned I would provide several links here and those will follow. Below those are the time stamps for the horizontal scroll bar "chapters" I discussed in the video so you can just ignore them.
Links
Reverse loop circuits www.azatrax.com
MRH article and forum forum.mrhmag.com/post/shortpr...
Nick's video • TVS installation on a ...
Chapters
0:00 Introduction
0:49 Chapters
3:00 Shorts revisited
3:33 Runaways
4:35 Decoder resets
5:38 Voltage spikes and current surges
8:35 Dead decoders at La Mesa
10:13 TVS diodes
12:05 Nick's tips and tricks
12:31 Reverse loop options
15:06 Frog options
18:36 Circuit breaker options
20:35 RC filters (snubbers)
21:11 Wrap

[@donaldshroyer8633]

Accept my gratitude and appreciation for adding Chapters to your videos. I know this will require more work on your part and feel it's important that you know that viewers like the result.

[@jhoodfysh]

Excellent video Larry. Thank you for your support in the hobby.

[@stuartwinstanley21]

Larry, excellent and timely video content. BTW your new chapters inserts are working just fine

[@davestott750]

Thanks for the chapters. Makes your videos really very useful. The ability to come back to a section at a latter date is great. I can remember seeing something but now I can more easily find it. 😀

[@paulwest3905]

Thank you Larry, this is so important for protecting our expensive decoders. Kudos on the chapters too.

[@elsdp-4560]

Thank you for sharing. Great information here, you got me thinking, I just could not imagine destroying the number of decoders that I have.

[@genejablonski9909]

I love the chapter feature. I know it takes you more time to create this but it is really a nice feature. Thanks

[@petertownsend8276]

Brilliant video. Very informative. Thanks. Pete

[@trapdriver7006]

Excellent informative video which I enjoyed watching. I installed the DCC Specialty px circuit breaker to the club layout as we had a lot of shorts which killed decoders. I can say it cured the shorts problem, I would highly recommend fitting one to a layout. I’m looking forward to seeing your next video Larry.👍😁😁😁😁🚂🇬🇧

[@andyknott8148]

Larry, this is a great video and I recommend anyone installing DCC to watch it. For the reasons you give, I removed the frog juicers from my UK club's large layout and used the switch machine's contacts. On a smaller layout where the points are manually operated by rods, I have attached micro-switches that change the frog polarity. As an electrical engineer of many years, I have never liked the idea of trying to correct short circuits in this way, as you say the spikes it creates can course chaos in associated layout electronics.

[@andrewpalm2103]

Thanks for this video, Larry! The MRH article was very interesting indeed. My layout is a very small shelf type and I'm relatively new to DCC, using an all-in-one DCS 52. There are only two Peco Electrofrog turnouts. I've never had a short that I know of, but I will now and then get some odd loco behaviour. I've always assumed it was dirty track or a DCC packet not being decoded correctly. But now I think I'll install a TVS across the power feed as some form of minimal spike protection can't hurt. At this point I'll leave my decoder installations as is, as my loco speeds are always very low and motor-induced voltage spikes following a short circuit recovery seem unlikely (I hope). Cheers from Wisconsin!

[@donaldkormos5529]

Larry ... your comment about "YET" was spot on ... and you're timing with this video was also spot on. I have a DCC-EX command station (Arduino Mega + motor shield) which feeds a Tam Valley 5-amp booster which then powers my layout track. The booster has short circuit protection which I checked without any trains on the track. Never had any problems. WELL, TODAY ... really today ... my layout was "YET" tested! A friend brought her three year old son over ... and of course I had to show him a train running. While the loco was running on the opposite side of the layout, the little guy found and picked up another engine and attempted to put it on the track. Bingo ... shorts!! Running loco kept going but the bell turned on and other weird decoder stuff. So Larry you are 100% correct ... things can happen that you never imagined or planned for. All the best ...

[@NitroStarGT]

Is your loco OK now? Did ya have to reset

[@3rdTrickGang]

This video was very helpful, I'm about to try some TVS diodes on one of my old Atlas RS-1s. I keep on frying decoders on it but my fleet of other DCC locomotives never have any issues. I'm thinking it's like you said I think it's the motor that is causing shorts on that specific locomotive. I love working on electronics but trouble shooting problems is another thing.

[@johnhermanson5249]

Watched the video on adding a TVS diode. I guess the polarity of the diode does not matter when it is soldered into the circuit because it is not mentioned (and comments were turned off for that video). I've used the Tortoise internal switches to control power to frogs for years (after cutting the frog area and insulating). One thing about older Tortoise (don't know if they changed the design) but back then I had to open the Tortoise and shave off some of the circuit board contact area because the internal switch would switch polarity much faster than the points and cause a short.

[@raquaro1]

Yet another great video! You mentioned keep alive's and unpowered frogs. I bought a NOS Bachmann GP with a Soundtraxx factory sound decoder. This engine WOULD NOT go slowly over my turnouts. When I opened it up I discovered that it was a single flywheel model. A large round speaker occupied the space where the flywheel would go. I have a few other short WB diesels that required a KA. But my standard GP and RS3's etc. ran fine through the turnouts. I cleaned EVERY contact I could find and no luck. Finally I took the board out, photographed both sides and sent the photos to Soundtraxx. I asked where can I solder a KA to this board. I got an response the next morning with a picture of the board with wires attached to the locations and a video on HOW TO SOLDER! (Funny!) I removed the train crew and installed the KA in the cab, and this engine now runs incredibly well! Thank you, Soundtraxx. THE BEST! Doing this small switching layout again I would power the frogs. Next time I will per your instructions!! Thanks again for your work!!

[@TheDCCGuy]

Bachmann locos also have pretty unreliable pickups on some of their locos which a stay alive can address too. In my opinion SoundTraxx has the best technical/customer support in the industry. Glad you got it sorted out.

[@daylightdave9405]

Thanks Larry for calling me out! lol... we all have our opinions and make that 12 years that Ive had my 3 NCE boosters with no problems... !! YET... 🤪 Ive run many of times on the La Mesa Club and would never put my own engines on their track... I stick with my tried and true method of within one to two seconds I have a remote control button in my pocket to shut down any part of my layout.... simple and easy... I always enjoy your Professionalism... Well done!! DD 😜

[@rjl110919581]

thank you for the great detailed video and super to week

[@thomasgrassi8817]

Larry Yes lots of information but all good information I have 4 reverse loops setup on my layout, I like the idea about setting the circuit breaker to use a manual option I have the NCE EB1 and that should be and simple task thanks for the insight on youtube chapters also will look into that for my videos

[@bernardc2553]

Excellent Larry gezz your hard work surely will help many of us thanks for setting up your Vids for those of us that need to rewatch over & over like myself. Not to smart but can lift heavy things tho lol

[@Mr._Darby]

I love the "chapter" feature!

[@thomascanady1967]

Bruce Chubb years ago in a video for MR showed how to use Peco contacts on turnout motors and Atlas Snap relays to control for reverse loops, wyes and frogs. Never tried the tortoise motors but the contacts sound the same as the others. Best way to control those areas without worrying about shorts.

[@TheDCCGuy]

Video coming!

[@ericbinns9167]

THANKS, Larry. Frog Juicers are removed and a PSXX-1 is on order.

[@michaelwright185]

Speaking of Azatrax, I have 3 of their crossing signal controllers which I have not been able to try yet.

[@TubaSoundsandTrains]

Hi Larry, thank you for this. I run on a small home layout and then on a very large club layout. I just recently blew an ESU decoder in a Walthers SD70ACE while running at home. I am pretty disgusted about the decoder and now I will look to install a circuit breaker, anything that will keep this from happening in the future. I also have two Tsunami decoders that were damaged, they are still working but even after a factory reset are not working properly. Thank you for your insight.

[@dthead]

just a question about this statement: "Using the contacts of a switch machine to reverse the polarity of a frog is normal for live frogs like the Peco Electro frogs - BUT will not help if a train runs the wrong way into the point if not set for that train, creating a short for as long as the point is against it. This is very common and the chief short/derailment cause." So would a sensor for every point be better to throw the point ? Yes a good set of videos.

[@TheDCCGuy]

One option is to create a stopping block for that situation. You can cut a gap in one rail leading into the heel of the turnout and wire the rail though one of the SPDT switches on a Tortoise or iP Digital switch machine so that the rail is only powered when the turnout is set for that route.

[@felipesanchezcuriel]

Thank you for all this information. If you use a relay to control polarity, do you need to add a capacitor?

[@TheDCCGuy]

If you mean to control the polarity of a reverse loop, then no, with a relay you would basically wire it a a reversing switch and use a triggering circuit/devcie to control it. That is what I did when I installed an Illuminator accessory decoder to activate a relay that shunted power to track 9 on my staging yard. in that case I used the ESP Wireless system to control the accessory decoder.

[@gsigs]

I installed an EB-1 on your recommendation and just as a warning to others the manual reset feature does not play well with Digitrax DCS-52 command stations. To activate the feature you have to program the EB-1 CV 131 to a value of 1 using ops mode programming. The directions for doing this that come with the EB-1 could be clearer. Upon testing by shorting across the rails I got mixed results. The majority of the time the EB-1 tried to re-establish power automatically, but once or twice it actually needed a manual reset. Not being an EE I can't explain this. I'm not saying "Don't get an EB-1," just saying that if you don't have an NCE system you might encounter problems setting up the manual reset feature. Also, if you are going to get a push button it needs to be "normally open." It doesn't have to be a push button, any switch that it momentary on will do (like those used for old DC switch machines).

[@TheDCCGuy]

I’d check with Ed at NCE tech support to see if he knows what is happening. Thanks for letting me know about the problem. I have only used it with the NCE PowerCab system.

[@marknovak2912]

I'm new to Dcc railroading. I would like to know what are "CV's and how you going about changing them.

[@peteengard9966]

I never lost a decoder but have had some get scrambled in the past.

[@michaelwright185]

Larry, I wonder if you have heard of or experienced problems (such as spikes or noise) with Atlas or Kato HM-5 motors? For all of you folks reading this who have the older PSX series, to disable the two second auto reset interval as Larry suggests connect a switch like an SPST toggle switch or am N/C (normally closed) push button switch to the J7-1 & J7-2 connector; the breaker will remain off after a short until the connection from J7-1 to J7-2 is momentarily opened.

[@TheDCCGuy]

Nothing specific on those motors, but then this is all a new facet of DCC. I need to explore all the various revers circuits available. I found that Digikeijs sells a little black box designed for reverse loops, the DR5013.

[@michaelwright185]

@@TheDCCGuy Sounds good - will look forward to that future report.

[@SammoKarm]

I used your advice with regards to lamps in series from the output of the Digitrax controller to the tracks sections, which light up whenever a short circuit occurs and it is working great. I don't think I need to add anything further, Or do you think I should?

[@marvinrogers8322]

N, in k k(k m m?k

[@TheDCCGuy]

I asked Larry Maier about ballast lamps and he said that for the voltage and current spikes they do nothing. They do limit the current flowing through the actual short circuit but thats about it.

[@SammoKarm]

@@TheDCCGuyBased on your research, I have now purchased a DCC-LSP Surge protector from DCC concepts. Thank you

[@marioangols3186]

Hi Larry, I saw the Nick Santo-related video for TVS, but is not stated or informed what kind of TVS rated for how much Amp? or type should be put on?. I have a normal HO scale layout and an ESU 50200 dcc station. Thanks and like always a good video.

[@TheDCCGuy]

I think that info is in the MRH article.

[@dkaustin98]

That was a good discussion. I am using four power districts. My DCS is Digitrax. I have snubbers that I have not installed yet. I am using a Digitrax PM42. I know Digitrax released a new version of it, PM74. However, online there is no mention of transient voltages. It does mention adjusting trip current. I do have some PSXX circuit breakers. Are all PSXX circuit breakers equipped with TVS circuits or just after a certain revision release? Old versus newer? Would I be better off using a new PM72 or the PSXX circuit breakers?

[@TheDCCGuy]

I have been using the PSX for several years, use zip cord for my power bus, have snubbers on top of that, and keep my fingers crossed, so far I have never killed a decoder and can’t recall ever having any CV corruptions. As I said in the video the PSXX is the only circuit breaker with both voltage and current suppression.

[@dkaustin98]

Larry, One other question about placement of these circuit breakers (if I were to swap to these.) In regards to Power Districts, I have one buss feed that runs 10 feet from the DCS, before the first track feeder meets the buss and has feeders scattered about the length of @20 feet of that buss. The only yard is in the middle of it. Does it make more sense to put the circuit breaker near the DCS or out on the buss before the first feeder connection? Just curious on your thoughts.

[@TheDCCGuy]

I have all mine mounted right next to my DCS240 with the bus runs feeding out from there in a palmate fashion. My yards have their own PSX units.

[@gregkujawa3012]

I'm using ME and Peco turnouts for their manual point throw capability to keep layout wiring simplified. I've also installed frog juicers. If I install PSXX circuit breakers and snubbers (RC filters) on the power bus, will that combination reduce the risk of decoder damage from voltage spikes? Thanks!

[@TheDCCGuy]

The PSXX will take care of the voltage spikes and current surges coming in from the booster. Snubbers take care of voltage spikes and help preserve the DCC waveform integrity due to wiring issues and should handle voltage spokes due to shorts there. So you have most if the issues covered. This is pretty much what O have been doing for several years although I have kept shorts to a minimum by having switch machines handle frog polarity.

[@ronaldrondeau7870]

Great informations, one question for you, I have a small switching yard that run on dcc with a NCE Power cab, what can I used to protect my engines

[@TheDCCGuy]

I would put a single PSXX on the power bus.

[@ronaldrondeau7870]

@@TheDCCGuy Who make that

[@chrisridd9423]

The chapters are very helpful, thanks! I'm a little astounded that decoders can react to voltage or current spikes by writing junk into their writable memory. That's a pretty unfortunate failure mode. Do the DCC specs require decoders to protect themselves in any way? Is there any evidence - anecdotal or otherwise - that particular decoder brands are more or less resilient?

[@TheDCCGuy]

I think it is mainly a matter of physics of electronics and as far as I know all decoders are susceptible. This subject of using TVS diodes is brand new to me and also to some of the electronics engineers I spoke with.

[@chrisridd9423]

@@TheDCCGuy does a TVS across the motor interfere in any way with the decoders that do back EMF sensing? Those seem to be very common nowadays, possibly even the norm here in Europe..

[@HumancityJunction]

So if I am using DCC Specialties Circuit Breakers then I should not need to also use the DCC Concepts snubbers? Is the surge protection only on the PSX-X and not on the PSX-1?

[@TheDCCGuy]

First the onboard TVS diode only removes spikes coming into the PSXX from the command station/booster so it won’t do anything about what goes on with your wiring which is what the RC Filters take care of. The PSXX has both the TVS diode as well as the current protection whereas the PSX only has the TVS diode.

[@chrisridd9423]

What happens when a metal wheel crosses a deliberate cut in the track rail, or an insulating rail joiner? Or one axle of a bogie's on one side, and the other electrically attached axle is on the other? It seems to me that for a fraction of a second, maybe longer in the bogie case, the metal wheel will be in contact with both rails, and you'll get a "short".

[@TheDCCGuy]

It depends on the purpose of the rail gaps. If they’re there to isolate adjacent power blocks then there should be mo issues. It is only when you have a reversing section or other change in polarity involved you can get a short. There can be some minor movements of electrons if two different boosters are involved but that is just one trying to match the power in the other. It is always best to adjust your booster to have a close to the same voltage as possible.

[@NitroStarGT]

Man, you have many great videos and I'm trying g to soak up all I can due to buying a bunch of Kato track and switches for a triple loop setup with inside yard. If I set this up on DCC, and I run I to a switch that is not in the correct direction, will that possibly kill a new $250 loco decoder with sound? It's easy to do when talking g or just plain letting train get ahead of your thoughts. I sure wished I had a local train store or group to make sure I'm not fixing to blow a bunch of money. I WANT DCC but I'm thinking of just staying with DC if it's this easy

[@TheDCCGuy]

Any time you create a short on the layout the resulting potential voltage and current surge could damage the decoder. However there are ways to reduce the chances of this occurring using the various devices I have shown in my videos. TVS diodes are the most recent of these and I have been finding them on a lot of the circuit breaker devices now that i know what to look for. The best advice seems to be to keep your DCC power bus runs under 30’ and limit the amperage going to them as this reduces the power stored on the wires further decreasing potential for damage.

[@NitroStarGT]

@@TheDCCGuy So if I run up to a switch that is simply not switched for me to go through it, on DC, I just lose voltage and the loco stops. On DCC the loco should just lose power also if the switch (Kato #6 power routing type) is not made correctly, correct? This scenario should not be a short if I'm thinking correctly 🤔

[@TheDCCGuy]

All depends on how they are wired and I am totally unfamiliar with Kato’s.

[@danshobbies13]

I’m no electrical engineer, but I have a small layout with one set of feeder wires. Couldn’t you put a fuse or resistor on the feed wires that would pop first?

[@TheDCCGuy]

Nothing I know of trips faster than electrons can move along a wire. Ballast lamps are little more than slow blow fuses.

[@jeffwardlow4626]

My NCE system red light is flashing showing a short on my layout but I be been checking my wiring and track don't see anything causing a short. Need help

[@TheDCCGuy]

Keep checking, you’ve created a short somewhere.

[@bobherbert6494]

Thanks for the advice. I have 2 old PSX-4s and the instructions say to add a NC pushbutton across j7-1and2 to put it in Manual reset mode. My question is, can I jumper all the 1s together and then jumper all the 2s together and then connect all the 1s and 2s together with one NC Pushbutton? That is instead of using 4 or 8 individual pushbuttons.

[@TheDCCGuy]

I’d have to ask Larry Maier what that might do to the ones that are not a shorted mode.I would not try it unless he says it’s OK.

[@bobherbert6494]

@@TheDCCGuy I tried sending Larry an email but it was returned undeliverable.

[@TheDCCGuy]

Did you use larry at tonystrains dot com ?

[@bobherbert6494]

@@TheDCCGuy thanks, I will try that.

[@charleymartin9422]

Hi Larry, Monday’s UK video 17th October hasn’t appeared !

[@TheDCCGuy]

As I said in the first video they might come out every week or every two weeks or possibly only once a month. It just depends on how backed up I get and the interest as gaged by number of views. The first one hit 2800 views but this one only hit 2200 so I may wait until it gets to 2800 before posting the next one although I am planning to post it next Monday.

[@brianbrooks7355]

Has anyone thought of doing their feeder & bus wire soldering with the work bench upside down? No tracks or scenery installed but an outline of where your tracks will go and pre drill feeder holes

[@TheDCCGuy]

The guys on Model Railroader Video Plus often will do that. Of course they are working with small layouts that have to fit in an elevator!

[@carlfisher2586]

Is it possible to add TVS diodes across our Digitrax busses to suppress spikes?

[@TheDCCGuy]

If you are using either the NCE EB1 or DCC Specialties PSX/PSXX circuit breakers then you are doing that already as they all have them across the track terminals. A TVS diode merely passes current up to its set voltage after which it blocks the excess so spikes don’t get through. I don’t know what the official Digitrax policy is on the use of these and this approach has only surfaced since April 2022 so we are still low on the learning curve.

[@PaulSmith-pl7fo]

Hi Larry. I have 60+ locos (not all DCC) but you don't mention a price for (or a link to) TVS diodes. The cost may be less than buying a new decoder but the work to add the diodes to each of my decoders would be prohibitive (for me). How about the DCC CONCEPTS DCC-BSS.2 Bus Spike Suppressors?

[@nicksanto882]

The cost of a 100 TVSs was slightly more than the shipping if I remember correctly. The bus spike suppressor will not protect from motor voltage spikes.

[@TheDCCGuy]

What Nick said.

[@claudiocfmmoto7027]

hi is somebody there able to repair a MRC ADVANCE SQUARE2 which was pugged in thr wrong power socket on my 10amp booster? thanks.

[@TheDCCGuy]

I think the only repair option is MRC.

[@eveannwallis4939]

Hi Larry, a great topic for your well presented video. However I'm somewhat uncertain as what to do, I would have thought that if it's voltage spikes rather than current spikes that need to be controlled, that 2 Zenor Diodes connected back to back ( opposing each other) across the track output from dcc station or EB1 (or similar breaker), would dump any excess voltage from the positive phase to the negative phase? As long as the rating of the Zenors is the same or marginally higher than the track operating voltage. Surely the EB1 or similar breaker would eliminate the excess current? To those who don't know what a Zenor Diode (ZD) does, it eliminates excessive voltage from passing, so a 12v ZD will only allow 12v to pass and dump any excess to a return (earth or negative). Please check out the link : kzbin.info/www/bejne/aqitm5V_osSkqJo In this tutorial, the circuit uses normal AC whereas DCC is similar but a square wave, and the fuse can be replaced with a breaker. Great videos, and I especially like your UK modelling interests and NCE eqt. Cheers, Eve