# DCC for Z layout



## Boréal (Jan 31, 2015)

I planned to use a HO D13SR decoder to supply my small z layout. Plugging the track on the motors outputs of the decoder. The decoder exploded. Twice. Anybody can explain what causes this? Thanks


----------



## fcwilt (Sep 27, 2013)

What was happening when the decoder failed? Trains running? Not running? Putting a train on the track?


----------



## Boréal (Jan 31, 2015)

Train was running since 2 minutes


----------



## JerryH (Nov 18, 2012)

Why did you attach the motor outputs to the track? They go to the motor.


----------



## Boréal (Jan 31, 2015)

To control the whole Z layout with the same throttle I have on hand when I operate my HO layout. You must know that my Z layout is a Livesteam for my HO figures! And because z decoders seem too challenging for me.


----------



## JerryH (Nov 18, 2012)

Since you are trying to run the layout instead of a single loco, I would guess that you are exceeding the amperage of the decoder.


----------



## Boréal (Jan 31, 2015)

I don't think so. Only one loco at a time. The layout is blocked and operates like a DC standard. I was a Micro-Trains SD-40-2.


----------



## fcwilt (Sep 27, 2013)

Possibly the train and track combined present a load that, while not drawing too much current, is interacting with the decoder in a bad way?

I have heard of folks using mobile decoders in this way.

So I would first try a different brand and perhaps a decoder suited for, say, an O gauge loco so you have plenty of extra capacity.

Something like this:

http://www.digitrax.com/products/mobile-decoders/dg583s/


----------



## Cycleops (Dec 6, 2014)

And how would you get an O gauge decoder in a Z loco? Fairly pointless. Take it to a shop or send it away and have a suitable decoder installed correctly.


----------



## JerryH (Nov 18, 2012)

I believe he is attempting to use the decoder to run the track and not a loco so it is attached to the track instead of in a loco.


----------



## Cycleops (Dec 6, 2014)

Sorry, should have realised he was talking track decoders.


----------



## JerryH (Nov 18, 2012)

I think it is a regular HO loco decoder but its being used to run the track instead. This may work with a DC loco, but he may have an isolation, shorting, or other electrical issue that is blowing the decoder. No doubt an unusual application.


----------



## Cycleops (Dec 6, 2014)

JerryH said:


> I think it is a regular HO loco decoder but its being used to run the track instead. This may work with a DC loco, but he may have an isolation, shorting, or other electrical issue that is blowing the decoder. No doubt an unusual application.


Why would he want to do this?


----------



## fcwilt (Sep 27, 2013)

Cycleops said:


> Why would he want to do this?


Well on my computer automated layout I am doing something similar.

I have a number of locos that are never going to be DCC enabled usually because of space limitations.

So my layout is capable of running DCC or DC locos. 

The layout is divided into electrically isolated blocks, about 40. Each block is fed either DCC or DC power as determined by a relay, one relay per block.

The DC power comes from a set of computer controllable DC "throttles", one throttle per block. The device I am using provides 8 independently controllable DC outputs per one circuit board, so 5 such boards covers the entire layout.

As a result I can run a mix of DCC or DC locos. The computer system takes care of feeding the correct type of power to each block as it always knows where each train is located (which block or blocks) and what type of power it needs.


While this type of system is not common I am not the first to do this sort of thing.


----------



## Cycleops (Dec 6, 2014)

Sounds nice and simple.


----------



## Boréal (Jan 31, 2015)

The layout has nothing else wired on. It is divided by block like old DC layouts. The only item that is on when I want to operate is 1 DC Z loco. The 2 decoders that blew up were brand new and are rated for 1.3 amp continuous and 2 amp stall.


----------



## fcwilt (Sep 27, 2013)

Boréal said:


> The layout has nothing else wired on. It is divided by block like old DC layouts. The only item that is on when I want to operate is 1 DC Z loco. The 2 decoders that blew up were brand new and are rated for 1.3 amp continuous and 2 amp stall.


Still the only thing I can think of is that the combination of the track and loco are presenting a load to the decoder that it does not "like".

If you don't want to try another brand of decoder or a larger one then perhaps some sort of RC or LC filter between the decoder and the layout.

Other folks have done this so it can work.


----------



## fcwilt (Sep 27, 2013)

Cycleops said:


> Sounds nice and simple.


Nice? Yes.

Simple? No.

It is nice to be able to run either type without having to worry about throwing toggle switches or whatever but there was a lot of wiring involved to be sure.

Here is some of the wiring from early on in the project - you can see some of the relays.


----------



## Boréal (Jan 31, 2015)

Thanks for the interest everybody. Meanwhile, I supplied the layout with regular DC: no problem! When I measure the output of the motor (grey & or.) on the decoder, it does not climbs gradually like a regular power pack from 0v to 12v. Instead I measure an immediate climb to 12v in speed step 1. My guess is this output is a 12v that is in peak forms that become more close to one another as the throttle is increasing. So, maybe the response of the 8v max MTL locos induces some irregular waves back to the decoder that its electronics makes it freak! Well, I am in for another operating mode with this Z!


----------



## DonR (Oct 18, 2012)

A Z loco is not, itself, going to overload a DCC decoder's motor output.
A typical DCC decoder is designed to handle from 1 to 1.5 amps. A Digitrax
decoder designed for Z is rated at 1 amp.

When you say 'exploded' is that literal, or that it simply failed?
When you say it 'exploded' twice, do you mean the same decoder
failed twice, or two separate decoders failed? Or did it (they)
simply quit but are still operable.

When you measured the motor output voltage was there
a load on the circuit? You can get wrong voltmeter readings
with no load.

Don


----------



## Boréal (Jan 31, 2015)

If you had just one Z loco on the track and the decoder 'exploded' there
must have been a short circuit somewhere on the track or
in your wiring. 

No short. All checked.

Did the loco move at all? 

The loco ran pretty weel for 2 minutes.

When you say 'exploded' is that literal, or that it simply failed?
When you say it 'exploded' twice, do you mean the same decoder
failed twice, or two separate decoders failed? 

Two brand new decoders. The same both.

Are you certain that you had the correct input wires on the decoder
connected to the 'track' terminals of your DCC controller?

Yeap

And are you certain that you had the correct Decoder motor output
wires to the track?

Yeap too!

These questions and the answers just about cover the possibilities
of your failures.

That is precisely why I don't understand... Thanks Don


----------



## DonR (Oct 18, 2012)

It is a puzzler.

I'm still a bit suspicious of some sort of temporary
short circuit or the opposite, an 'open', such as
when the loco loses electrical contact with the
rails. It is likely that the decoder could
not 'take' even a momentary anomaly. It is designed
to be connected directly to the motor where
neither event is likely.

Tiz a shame, it would be ideal for Z control.

Don


----------



## 400E Blue Comet (Jul 11, 2014)

Ouch! Sounds nasty...
To be honest, I'm not that experienced with DCC or Decoders, but one thing that immediately raises a red flag is HO. HO, is, of course, a totally different size than Z. I could see even more of a problem if you used a Marklin HO decoder, as Marklin HO, or the older ones usually use AC, not DC like Z scale does.
The weird thing is if you were using an AC decoder, DC is usually compatible with AC trains. Maybe it's because chips have such fine wiring. Considering HO uses more power, and DC used for Z Scale is compatible with DC and AC currents, it should be able to support something that takes less power. What does your layout look like? Maybe it's too big, too complex, or somehow incompatible with the decoder. Are you using old or new Z Scale? What part of the Decoder is exploding?
My suspicions would be A.) The Decoder is not compatible with Z Scale for some reason B.) You might be using an old train, dunno if the decoder can run old and new or just new, or C.) There's a problem with the wiring. Like I asked, which part of the Decoders is "Exploding"? Do you have any pics?
If the Capacitors/Battery like things are exploding, (If decoders even have those) make sure they're not getting overloaded, or they're not on the wrong way. If you give them the incorrect polarity or feed them too much power... Well... I'd like to congratulate you on discovering a substitute firecracker.
The best you can do? Try a decoder made for Z, and make sure the wiring in the track hasn't gone wrong.


----------



## Shifty1 (Apr 2, 2015)

Ima noob... but im an electronics tech by trade. I've been researching dcc for a while. My understanding is that dcc converts or changes your track current from dc to ac. The loco decoders have built in ac dc wizardry to a: enable the dc motor on the loco tocope, and b) listen for digital commands for its addy. With ac the amps are bumped up, throw in digital amps etc... bear with me im thinking aloud as it were.

Someone earlier mentioned marklin ho. I haven't looked into them too much but I know the track/pickups are different.

Does your straight.. (non decoder equipped) loco whine or run louder than it used to?


----------



## fcwilt (Sep 27, 2013)

Shifty1 said:


> Does your straight.. (non decoder equipped) loco whine or run louder than it used to?


The signal on the track is basically a square wave whose peak-to-peak voltage depends on the settings of your DCC command station.

On my HO layout it (a Digitrax DCS-100) runs 26-28 peak-to-peak. 

A non-decoder equipped loco just sits there and hums/buzzes/squeals and may overheat.

Some command stations have a feature that (in theory) allows running one non-decoder equipped loco but in practice it doesn't work very well and may damage the motor.


----------



## Cycleops (Dec 6, 2014)

Shifty1 said:


> Ima noob... but im an electronics tech by trade. I've been researching dcc for a while.


If that's true you should know more than most of us!


----------



## Shifty1 (Apr 2, 2015)

Lol Cycleops, research is one thing. Practical use is another! 

But as fc stated... "in theory,"


----------

