# DCC Track Only Reading 2 Volts?



## RollingThunder (Feb 15, 2018)

Hey Guys

Running a N Scale DCC Layout using a NCE Power Cab...

So i decided to check voltage on my track and i'm only getting a 2v reading across my track (I believe n scale should be about 12v in total)... 
Anyone with experience or solution please chime in...

Thanks


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## Lemonhawk (Sep 24, 2013)

Do you have the meter set to read AC? The DCC waveform is sort of AC so the only way to get a semi accurate reading is by setting the meter to read AC.


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## Gwent Rail (Jan 24, 2018)

In my experience (both in trains and as an electronics development engineer) if you are really getting low voltage through any sort of electronic connection, by far the most common reason is a loose power feed (or return).
Your first action should therefore be a check of your connections between your power supply and then the wires to / from the track.
It may be as simple as a loose wire and that's the easiest and cheapest to fix.
Hope this helps.


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## RollingThunder (Feb 15, 2018)

Lemonhawk said:


> Do you have the meter set to read AC? The DCC waveform is sort of AC so the only way to get a semi accurate reading is by setting the meter to read AC.


Hi Lemonhawk 
Yes meter was set to AC, Thanks...



Gwent Rail said:


> In my experience (both in trains and as an electronics development engineer) if you are really getting low voltage through any sort of electronic connection, by far the most common reason is a loose power feed (or return).
> Your first action should therefore be a check of your connections between your power supply and then the wires to / from the track.
> It may be as simple as a loose wire and that's the easiest and cheapest to fix.
> Hope this helps.


Hi Gwent Rail
I will go ahead and check the wiring connections... Thanks


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## RollingThunder (Feb 15, 2018)

OK, so i checked the wiring and connections, i didn't find any problems.
I also checked the NCE cable and connections into Power Cab and Power Cab Connection Panel for any bad pins, also no problems.

I even took a reading directly from the 2 power pins coming out of the Power Cab Connection Panel, about 5v from one and 4v from other. when i connect multi meter probes to both im back at 2v.

My next move is to get another multi meter from HD today just to make sure... After that i'm out of ideas...

Thanks


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## DonR (Oct 18, 2012)

You didn't say whether your train was running
on your track. If it's running there is a problem
with your meter.

Don


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## mesenteria (Oct 29, 2015)

Could be the power supply....? Could be the command unit, could be the meter.

Electriks. What would we do without 'em?


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## Shdwdrgn (Dec 23, 2014)

You need a good meter that reads 'true' RMS voltage. I have a cheap meter that claims to read RMS, but it doesn't, so I only read about 1.7V across my rails. Yet if I hook up a bridge rectifier to power something from the tracks, that shows me a little under 16VDC so I know the correct voltage is present (note that the bridge diodes will drop your voltage by 1V or more, and my source is 16.5VDC).

The big question is whether or not your trains are running at speed? If you only get a slow crawl at full throttle then you probably have a voltage problem. If the trains actually run at full speed then you're good to go. Note that all of the DCC decoders I know of require a minimum of 3.3VDC before they will even operate so if you are truly only getting 2VAC across your rails then the decoders wouldn't even turn on.


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## Lemonhawk (Sep 24, 2013)

I just tested my track (Digitrax controller) and on AC the meter reads 15v (also what the power supply reads). On DC the meter reads 19 mv. My guess is any meter that reads AC and DC will have a full wave bridge involved when reading AC. 2 volts seems high with a meter set to DC. We await your answer about if the loc's actually work! Doesn't the NCE power cab have a setting that reads the voltage? What does it say the voltage is?


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## Shdwdrgn (Dec 23, 2014)

Lemonhawk -- just for clarification (and I know you were responding to OP) my was WAS set to AC when it read 1.6VAC across the rails. It even has "True RMS" stamped across the face of the meter, but that's obviously a lie. So I don't doubt what OP is reading just because I have seen the same thing on my own track.


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## RollingThunder (Feb 15, 2018)

Did not get a chance to test a new meter today ...
Just to clarify and maybe should have mentioned earlier... Yes my loco is running and does run from crawl to faster, it just doesnt seem as zippy as when i was using the Digitrax DCS51... 

With the Digitrax hooked up a few months ago the same meter read 12.3v, it's a mystery. Anyway i guess it's the meter at fault.
Thanks to everybody who chipped in, i'm still learning about DCC etc.
:thumbsup:


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## DonR (Oct 18, 2012)

Yes, if the loco runs the correct voltage is
getting to the decoder. The 'less peppy' performance
could indicate track and loco wheel cleaning is due.
Possibly the truck lube has gelled somewhat which
also could affect smooth running.

Don


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## Lemonhawk (Sep 24, 2013)

I think the "True RMS" is only if the waveform is a sine wave. The reading across the DCC rails is also dependent upon the pulse width modulated signal coming from control unit. It's still a little puzzling to me that you can read such a low voltage and still have it all work. I do know my meter is not a "True RMS (Root Mean Square)" meter so its probably just reading the DC voltage after the PWM signal goes thru the diode bridge. Not having a NCE unit I also can't verify that it has a display of the track voltage, but I believe that its true. Best way is to use an Oscilloscope, but few have one of those. Back to solving the OP's question.


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## MichaelE (Mar 7, 2018)

What is the fascination with checking track voltage on a DCC railroad when everything is running correctly?


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## RollingThunder (Feb 15, 2018)

MichaelE said:


> What is the fascination with checking track voltage on a DCC railroad when everything is running correctly?


I'm a bit OCD when it comes to things working as they should 
When i asked the question i was not aware of a few DCC facts that were pointed out by other members...


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