# DCC help needed



## mopac (Feb 24, 2011)

Got my super chief DCC 8amp set in the mail yesterday.
New layout not built but getting everything ready. I also
got that digitrax 20 amp power supply. Looks like they
want a fuse or circuit breaker in line with the wires from 
power supply to command center. It comes with a y cable
to hook up another booster. The y cable has 5 amp resetting
breakers on each lead of the y. If I use that cable for power 
supply I have turned my 8 amp into a 5 amp. Am I right? I am
new to DCC. Never used it. What would you guys suggest for
an inline 8 amp fuse or breaker? Resetting would be best. Can
I get one at lowes or HD? Thanks for any help.


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## NIMT (Jan 6, 2011)

Yes that Y cable business is a little confusing, take that fine device and chuck it in the drawer. Your going to hook up to one set of posts on that power supply.
Go to your local auto parts store and get a in line circuit breaker. The have ones that fit into a standard fuse space, and you can get an in line fuse block to plug the breaker into. One of those on either wire will work!


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## mopac (Feb 24, 2011)

Thanks Sean. I will get one there. Good idea.
So only one wire needs to be fused and they should have 8 amp fuse or breaker?


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## NIMT (Jan 6, 2011)

Yea one wire will do it!


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## Brakeman Jake (Mar 8, 2009)

In most layout applications,5 amps. is already more than enough power that you won't need unless you run quite a few trains simultaenously and 8 amps. could be considered an overkill for many home layouts.My opinion...I'd use this split cable...both power supply and command station will stay cool and your decoders/locos will be better protected.And should a booster become handy in the future,you'll already have somewhere to plug it.And come to think of it...don't you think the Digitrax people know what they're doing?


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## NIMT (Jan 6, 2011)

Jake,
I don't think you understand what the Y cable does. The Y cable splits (1) out of the (2) 10 amp outputs into (2) 5 amp outputs effectively giving you (4) 5 amp outputs, and since he only needs 8 amps of the available 20 amps it shouldn't have any overheating problems.
Mopac has gotten a DCS200 8amp DCC controller feeding it only 5amps out of the 8amps that the unit is capable of controlling would be a waste of 3 amps of available use. I have been running an 8 amp main and (3) 8amps boosters for a total of 32 amps and have never had any problems with over amping any decoder or any other DCC device. The Digitrax DCS200 has a very fast overload circuit and should never cause a problem!
The only thing I have done with my DCS200's is to bolt a PC power supply fan onto the heat sink so that I never had an overheating issue, but that was really for when I was running my system in a 100+ degree shop in Phoenix,AZ.


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## mopac (Feb 24, 2011)

12 powered units would probably be the most I would run but 
that would eat 5 amps up in a hurry and a 5 amp lead would
blow and cut my power. I want and need the full 8 amps and like
Sean I will add a 5 amp booster if I find one kinda cheap, giving
me 13 amps. Bit of an overkill but won't hurt a thing and nothing
would be straining. That power supply would still be in idle. I need
a fan also for the command station. Power supply has one in it.

Wow Sean, 32 amps. You are ready for anything. Do you use 2 of those 20 amp power supplies?


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## NIMT (Jan 6, 2011)

I started out using individual 16 VAC transformers for each unit and found that too noisy, loud and hot. I then switched to a AT computer power supply that fried one of my controllers. I now use a 28V DC telephone system power supply that puts out 40+ amps that I limit down for each individual controller/booster. With the unit having a higher input voltage for the controller the setup has substantially less voltage and amperage lost than a small supply. I also have no overload or under amperage issues.
I like being at the highest threshold of the voltage and amperage settings that way when I setup an engine or other equipment with DCC decoders, LED's, Sound, or any other controls, I'm pretty much guaranteed that a customer receiving the unit will not just have it fry out because they pushed it harder than I do!
I also like running a lot of engines at once!
As far as cooling the controller/booster, a 3" computer fan works great. I just bend the head of the bolts just slightly to be able to attach it to the heat sink fins, and you can just hook the power leads right to the input power for the controller.


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## mopac (Feb 24, 2011)

I like the way fan is mounted to the unit. I am not very electrically inclined.
Why 3 wires from fan? What power does the fan need? Just from the output
of power supply? Thanks.


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## Massey (Apr 16, 2011)

I have a 5 amp unit and I have only once had it power down from overheating. It was in a box that was getting direct sunlight from a nice Virginia Beach summer and the room didnt have much air flow from the AC (layout was blocking the vent) The DCS100 shut down after about an hour of running and the sun heating up the box the unit was in. I added a small 5" desk fan on the top of the box blowing down on the DCS100 and no more shutdown issues ever happened. 

I would not worry about overheating a unit if you simply add a small fan like Sean did or like I have that is simply blowing over the heatsink on the back of the unit.

As for the Y cable... get rid of it. The power supply is only going to give the command station the amount of amps it asks for, so if you are only running 1 engine at .5amps the power supply is prolly going to only be giving .75 amps to the controller. The other 1/4 amp is for the command station's internals. Now add a few more engines or short the unit and you will see a much higher draw. I would recommend having something on the rails to protect the command station from anything that happens on the tracks. A PM42 works great for this. And the fuse or breaker on the PS is a good idea for anything comming into the command station.

Massey


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## Massey (Apr 16, 2011)

mopac said:


> I like the way fan is mounted to the unit. I am not very electrically inclined.
> Why 3 wires from fan? What power does the fan need? Just from the output
> of power supply? Thanks.


Red and black are 12V DC to the fan and the yellow is for the motherboard's BIOS chip to read the fan's RPM

Massey


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## Brakeman Jake (Mar 8, 2009)

You guys are confusing me....It is my understanding that adding boosters to a DCC layout is in no way an increase in total available amperage to a particular district,but rather adding other district(s) so that the extra power is somewhat evenly distributed through the whole layout.Put simple here....take a 5 amps. command station and add to it an 8 amps. booster....will it give you a 13 amps. district?No way the way I understand it...you'll have two districts...a five amps one and an eight amps one.

So...if one added a booster to his layout so that he could run more locos,he'll still have a shut-down should ALL his locos enter one single district at the same time.OK...not likely...just suppose it could happen?So the 32 amps. you have on hand is indeed a lot but nowhere on your layout you do have 32 amps.Electrically speaking,you have four eight amps. layouts linked by a common digital control.Isn't it?Or am I completely foolish with my comment?


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## NIMT (Jan 6, 2011)

Jake,
You can do it both ways. 
I can run either 32 amps to the entire setup or I can divide it out into (4) 8amp districts.
I use mine in the later 8amp districs still allow me to run anything I want anytime I want.

Mopac,
Like Massey stated the Yellow is a tach/rpm lead just disregard it, and yes just hook up the Red and Blackup to the power that feeds the command station.


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## Massey (Apr 16, 2011)

13amps of available power does not always mean at the same location. I have 5 amp DCS100 and a PM42 split 4 ways. This does not mean I have 20 amps of power but I can have a total of 5 amps between my 3 districts and 1 reversing loop. if I were to hook up my DB150 to 2 of the power districts then I would have a total of 10 amps to my layout but not 10 amps in one single district. I would have a total of 5 in 2 districts and 5 in 1 district and 1 reverse loop. but it works out to 10. 

By using power districts powered by additional boosters you get an overall additive amount of amps but you are still limited to the amount you can draw in one district at one time.

Massey


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## mopac (Feb 24, 2011)

If my entire layout is one power district and I add a 5 amp booster to my
8 amp command station what would the total available amps be at any place 
on the track? I thought it would be 13 but I might be wrong. Jake seems to 
think not but I think Sean is saying it does add up. Just asking.


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## NIMT (Jan 6, 2011)

Your overall layout amperage is still going to be the sum of all the amperage values that you supply the rails no matter which way you hook it up. Amperage potential at any given point will be what you supply to that point! 
I would avoid adding up the controller and the boosters to get more amps, it can lead to some very undesirable results! Get it wrong and you could end up with an ark welder! Keep the controller and boosters set up on different districts and you'll end up with a lot less problems.
Using PM42's will only add to the overall safety and continuity of the entire setup! 
The main point is to supply enough amps to be able to run what you want to run! I would say that 5amps will run what most people can throw at it, and 8amps will out do most!


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## Brakeman Jake (Mar 8, 2009)

OK...let's see...the only way that I can see that the total of a 5A station AND a 8A booster could give a total of 13A to any specific section of track (in short a 13A district) is if it was possible to match rail A power from the station to rail A power of the booster (and then same for B rails).Theoretically,it would add up but I have a hard time to see how.

From what I know,DCC current is a form of AC current and the only way I could imagine it could add up is by being perfectly in phase between both power components.Now...can the loconet connection make this possible?I have serious doubts and definitely wouldn't attempt it.

The way I understand the system,you could have as many districts as you want (through as many boosters and/or booster configured command stations and/or PM42's) but you can never have a single district of more than what a single booster can supply(8 amps. max. in this case).Indeed,one could have a huge power supply to power the whole layout(like the 32 amps. discussed above) and not be worried about a power shortage and that's great BUT nowhere on the layout can that power be required in any single district,8A being the max any booster can handle.

And even if it is possible,I'll never give it a try for safety reasons.First,there's going to be a lot of foam on this layout and I want it as safe as can be.Then,decoders(specially sound ones) are costly and I want them protected too.I have a DCS200 on hand and it's 8 amps. power will be distributed through a PM42 set at "fast trip" or about 1.5A per district to achieve just that.It will probably annoy me sometimes by tripping a little fast but since I'll not run more than two or three N scale locos at a time,I'm confident it will be just nice.

I may be exagerating and may have a lot I don't know,but I'm at school on this forum,so please guys...teach me.


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## mopac (Feb 24, 2011)

Me too Jake. I have learned alot here but so much more to learn. I am
brand new to DCC. Got my set saturday and still haven't had time to try 
it out. I am just going to do the quick start in the manual and learn from
there. I have 2 DCC engines that I have been running in DC. I have a ton
of analog engines ( mainly athearn blue box and proto and rivarossi) that
will need installs. Looking forward to it all. I just like to know as much as
I can before I dive in. I am that way on everything. 8 amps should do me fine
so no adding boosters to same district. I can live with that. I was just thinking,
you know sometimes that is dangerous. HaHaHa.

What are the advantages of doing power districts versus powering the whole
layout in one district? I know it would be easier to find a problem area. And be
able to shut down lets say a passenger train area and could shut the lighting 
down on the passenger cars. I have plenty of passenger trains. So that will be
a concern. Would it be wrong to wire layout as one district? I guess a few sidings with on/off switches would be fine.


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## NIMT (Jan 6, 2011)

Rail matching and phase matching can be done with a combination of PM42, loconet and the control unit. 
But let me reiterate just don't do it!!! It's not worth the risk!
I have run 14 HO engines off of an 8 amp unit without a problem. So why would you want more than that?
Having several districts run off of either it's own control station / booster (costly), or having PM42 divide up several control stations / boosters is a lot safer bet.
You had mentioned in an earlier statement about under rating the supply amperage that you supply to the unit for safety, That is actually the opposite if you give an DCS200 8amp only 5amps input you are limiting the ability for the unit to have control of the power that it needs.
Think of it as driving a truck with the transmission in too high of a gear and working the engine too hard!
You brought up a good point on protecting the sound decoders, I hear all the time about people frying their decoders because of a derailment????? I have max amperage and I've never in 15+ years of working with DCC fried a decoder because of a derail, It has got to be a cheap DCC controller running their system.
Another would be a fire caused by a DCC system???? I've been running DCC with alcohol track cleaning car for 10+ years and never once torched one of my layouts.
Using a DCS200 8amp for N you should be able to run more loco's/Engines than you can physically or mentally be able to manage!


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## NIMT (Jan 6, 2011)

mopac, 
It is better to wire decoders into your lighted cars for control then to kill track power!
Power districts help with trouble shooting shorts, keep from over amping equipment, and provide reversing circuits.


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## Massey (Apr 16, 2011)

I have my PM42 set for max tripping speed and I can say that it does not trip all the time and even with 4 or 5 sound locos on the rails at power up it may trip once or twice from the on current surge but I cant remember it tripping more than that. Both my yard and my staging tracks are on the same PD and that is where my engines are usually parked when I am done operating my layout. I have had 10 engines on the rails at the same time in both places, 4 sound and 10 non sound and no issues with a 5 amp setup. Oh that is in HO scale. I have had 5 engines operating at the same time on my layout with no power issues and again 5 amps in HO scale. 

If you are adding extra boosters you NEED to devide the layout into power districts. DO NOT run 2 boosters in the same district at the same time. The loconet does phase match the boosters so you dont short between power districts but that does not happen right away. If you have 2 boosters in the same district you WILL fry one or both due to unmatched phase alignment. The phase alignment takes a couple of seconds to occure after the units power up and will only work if the second unit is set up as a booster. 
Digitrax designed the command stations to act as both a Command station and a booster depending on how it is wired up. The unit that is designated as the command station controls the phase. Once powered up it sends a timing pulse through the loco net to the other boosters in the loconet and the boosters then align their phase to match in polarity and sync. Now if one of the boosters is set for auto reversing then it does not match the phase but it does match the sync so the phase is either at 0° or 180° in or out of phase so when it is tripped it will be exactly oppisite or in sync. Yes this all happens on the locobus along with the other data that is sent around. The phase signal is not transmitted constantly and is only retransmitted when the booster or command station is shorted. When a booster set for auto reversing is tripped it checks the sync with the command station as well but ignores the phase.

I hope this helps clear up how the boosters work with the phase. I am not sure how NCE or any other DCC system handles the phase issue but all must have some way of doing it.

Massey


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## Brakeman Jake (Mar 8, 2009)

Thanks for the great infos,plenty of them indeed too.But sometimes,having a lot of infos can become more confusing than helpful wich is not the case here.Crisp,very clear and quite complete...thanks again for me and all the others it'll likely help.

Here's a description of the setup I have decided to go with.First,the power supply.Digitrax state in their command station instructions that they need 12 to 28 volts,either AC or DC to operate,and that any excess voltage will be dissipated through the heat sink.Since 12V is enough for N scale,I bought a 10A/regulated 12VDC power supply so there should be little if any heat to dissipate.I have tested this setup and my DCS200 seems to like it.

About five years ago,I have bought an older DCS100(with speaker type connectors) that was still brand new as the original owner had never built any layout and had dropped the idea.But then,I got a DCS200 on Ebay at a great price so decided to go for the added power and functions,with in mind that I could use the DCS100 as a booster.I did reconfigure the DCS100 as a booster(piece of cake) and tested this setup...it works fine.Then I realized that the size of neither my layout nor my fleet justifies this kind of power,I decided to reconfigure the DCS100 to command station status and keep it tucked in a drawer as a back-up unit,should the DCS200 fail.A luxury...well...I have it on hand and probably couldn't sell it anyway.

I've had a strange experience on the local club's layout four years ago...I was running an older DC steamer on "zero stretching" (not recommanded,I know)when I accidentally drove it to a wrongly thrown turnout...the motor fried instantly with a glorious smoke plume and the smell.There was also a neat burn trace on the ballasted track.That's when I realized that a full 8A could be a nasty current should a problem occur.

This is when I decided that I'd do my best to protect my precious sound decoders so ordered a PM42 to be able to not only divide my layout,but also have a amperage limiting device so that this does have limited chances to happen again.So my DCS200 will be splitted into four districts with the PM42 set at "fast trip",a district for each of my three mains and the other one for the yard.

I'll have two reverse loops in my wiring diagram,so I'll need a pair of AR1's or better to handle them and I'm pretty confident I shouldn't have any problems,but may be wrong.I have yet to know how to set them up properly but I think it should be easy.

Someone sees a mistake in this setup?Or a better way to do?Please,by all means let me know.I'm in no rush and want reliability.Thanks.


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## NIMT (Jan 6, 2011)

Jake,
Only one little detail, you don't need AR1's the PM42 will also do reversing.


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## mopac (Feb 24, 2011)

I can't help you Jake. Too new at this. I did finally get my DCC wired to some track today. First time messing with DCC. Its going pretty well. I was messing with some cvs and at one point had to set decoder back to factory settings. I must have done something the system didn't like and command station shutdown for a second and everything was screwy till I shut power off for a few minutes and then everything reset.
Engine wasn't running, I was just resetting cvs and it freaked out. Only lasting problem now is with the engine. When I back throttle down to 00, motor stops but headlight and sound still on. Engine is a bachmann spectrum 4-6-6-2 with a tsunami decoder. I have set it back to factory settings. I guess the decoder is coming on at to low of power.
Any ideas?


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## Brakeman Jake (Mar 8, 2009)

NIMT...indeed the PM42 does reversing but I read somewhere that the four "sections" do either reversing or act as breaker,not both at at same time.I need the four "breaker" functions.

MOPAC...in DCC mode,lights and sounds don't turn off when backing throttle down(as with DC),you have to turn them off on your throttle control.That's the beauty of DCC,lights stay on and engine keeps idling until you turn them off manually on your throttle.I don't remember for sure wich commands do this...you'll have to look into your instructions booklets.You may have to adjust a CV or two to match your decoder settings with your handheld commands.


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## Massey (Apr 16, 2011)

The way you wire the PM42 determines the mode it is in so no it will not do both overload protection and reversing. BUT that being said it is a good idea to get another PM42 for the reversing over a couple of AR1s for a couple of reasons. First the AR1s do not provide short protection and the PM 42 can to both for you (I know I said it cant do both at the same time but I will explain in a sec) and the price of 2 AR1s is almost a PM42.

To wire the PM 42 for the safest function on a reverse loop you will need to wire at least one channel for overload protection and then apply the output of that channel to the inputs of the PM42's reversing channel(s) In order for the PM42 to have short circuit protection of the reversing section you will need to use one of it's channels for overload if not then it will rely on the breaker in the command station. One channel for both reverse loops will be fine but you can also use one overload channel for each reverse loop... your call.

Massey


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## NIMT (Jan 6, 2011)

I have to say this a very complex and interesting conversation!
Well worh the read!:thumbsup:


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## mopac (Feb 24, 2011)

Sounds like that pm42 is a good thing to get. Its on the list now.
Thanks Jake. That crossed my mind that I turn them off. I know 
how to do that. Thanks. Then all is well. I had a good day of learning.


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## Brakeman Jake (Mar 8, 2009)

Massey,I like the idea of a second PM42.Considering the price difference with a pair of AR1reversers,this is an obvious choice.It will open other setup possibilities that I'll study later but I'll likely go the simplest way...use two sections as reversing for my loops and keep two free sections for possible future needs.

However,I have another question.I was planning to use 14 Ga. wires for my leads but looking at the PM42's blue connector,I find the solder tabs rather flimsy for this wire gauge.Do you think,assuming I'll run N scale,that I could reduce the size to 16 or even 18 Ga. wires and still be safe?My longest lead shouldn't exceed eight feet since the layout will not be a large one to start with.


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## Massey (Apr 16, 2011)

Brakeman Jake said:


> use two sections as reversing for my loops and keep two free sections for possible future needs.




Doing this will cause the entire layout to shut down if there is a short in the reversing section. This is not a good thing and defeats half the purpose of the PM 42. I would use one channel to control the overload protection for both the reverse loops and that way you have a free channel still for future expansions.

Massey


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## Brakeman Jake (Mar 8, 2009)

I forgot an important detail in my last reply....I want breaker protection everywhere on the layout through four sections of a first PM42(three mains and yard).The way I see it now,I could use a second PM42,set two sections as breakers then link the outlets to feed the two other sections set as reversing circuits to feed my loops.In short,the first PM42 would feed the basic layout and the second one would handle the return loops.But there are other ways to achieve the same results,I'll have to give it more thoughts.


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## Brakeman Jake (Mar 8, 2009)

I have re-evaluated my needs and guess what?I already have on hand more power that I'll ever need,given I'll never have a big layout and that I'll never run more than two trains operating alone and may be one or two more with another occasional guess operator.

So...I studied my hardware,in occurence a DCS200,an "older" DCS100 and a PM42...a lot of power for my needs indeed.And in the process,I simplified the shematics somewhat.A second PM42 is a good idea but I'll use the one I have and save the $$$ for going wireless eventually.I already have the DT400R and a UR91(or 92) would complete the system very nicely.

So it goes...looking for flaws you guys may find...I'll use the DCS200 through PM42 section 1and 2(set at fast trip) to power my two parallel mains and the DCS100(set as reversing unit) through PM42 section 3(also set at fast trip) to power my third main (wich has loops) and my yard,keeping section 4 for future needs.

I have tested the DCS100 as a reversing unit and it works fine but I have a question...If I use the DCS100 as a reversing booster and push its output through the PM42 set at fast trip,wich will trip first?If the breaker trips too fast,won't it deny the DCS100's capability to identify the polarity conflict and react?I suppose the PM42 could see the polarity conflict as a short so should I set it at a slower trip speed to allow the DCS100 to see it?

If so,I'll use the DCS200 (forget the DCS100)then use the third and fourth PM42 sections as breaker and reversing circuits (no more spare section) but then,what's best?Breaker first then the reversing circuit or the other way around?Digitrax's instructions don't mention this.


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