DCC system resets when accelerating locomotives

Model Railroader Electronics and DCC
1

On my NCE DCC Power Cab layout, after over 10 years of successful operation, my DCC locomotives began to reset the system after I had accelerated above 3 or 4 on the 28 speed setting. By reset, I mean that the system turned off and then went through its starting cycle.

Using my multi meter I looked for resistance and found heavy resistance in one rail leading to a turnout. I suspect it must be the problem, but I don’t know what to do about it. Should I make new wiring connections there? Should I get a new turnout? What is the best way to handle resistance? Thanks for any advice.

Additional info:

My layout is small. It’s the Yule Central from the Small Railroads You Can Build, edited by Bob Hayden in 1983. It’s an oval on a 4 x 6 foot table with two spurs, a tiny run around track, and a small two track stub yard. There are six Atlas snap turnouts and four DPDT switches for block control.

I converted to DCC around 2010 by upgrading wiring. I installed a 14 gauge bus line and attached the 22 gauge feeders with solder and suitcase connectors.

I sent my PowerCab into NCE and they tested it and found that it was working perfectly (I have the 1.28C Chip). They suggested I test my decoders and wiring, and perhaps consider purchasing a Smart Booster.

Further testing my PowerCab system on an EZ Track oval showed my decoders and PowerCab were working fine. Some of my decoders required resets to factory defaults.

I tested my wiring for short circuits using the “quarter test,” and each time the quarter was laid on both rails my system turned off.

2

That odd rail should be fixed first. It seems an obvious possibility.

I’m baffled as to how one rail can develop resistance except across a joiner or at the rail surface due to dirt.

If it might be dirt then clean the rails. Small layout shouldn’t take long. Rag and rail cleaner of your choice.

If no difference I vote you take out the high resistance piece of track and replace it with fresh track.

If these steps make no difference only then maybe start hunting for the troll under the bridge…

3

You shouldn’t need a booster for a layout that small, expecially since you didn’t need one for years.

I’m not understanding why high resistance rail would not just stop the train rather than reset the PC. I’d drop a feeder to the high resistance track, easier than tearing out track and ballast.

I was assuming but maybe I shouldn’t, is the loco on this high resistance track when the PC resets?

4

When you sent in your PowerCab, did you include the power supply or just the cab? It’s possible that the power supply is going bad and needs to be replaced.

Joe

5

Hello All,

Thank you for the detailed update.

One more question…

How many locomotives do you run simultaneously?

Is it possible that you are now exceeding the 2 Amps of the system?

You didn’t mention any track cleaning regime. Have you tried cleaning the suspect rail, associated contacts, and rail joiners?

The resistance of a dirty rail might mimic a higher load and possibly trip the system.

Another thought is the solder joint to the rail has become corroded.

If you can try to resolder this joint. Avoid using paste-type plumbers solder. I recently switched to Rosin Paste Flux (SRA Flux# 135). After resoldering clean the joints thoroughly with Isopropyl Alcohol.

Also, “suitcase” connectors have been known to fail. If you can replace this connector.

While you are at it inspect the wires to see if they were damaged at the time of initial installation.

If the connector cut into the wire, thereby reducing the number of strands, this can create resistance between the bus and the feeder wire. Which could create the resistance you are measuring.

Thank you again for taking the time to make a separate, more specific, post about your situation.

Hope this helps.

6

with just one loco? (a new loco)?

of course increasing the speed of a locomotive increases the current and will depend on the condition of the motor, the # of cars and grade. (a typical loco shouldn’t exceed 2A spinning it’s wheels)

a higher resitance is going to reduce the current not increase it, exceeding the limit of the throttle.

7

A high resistance is not going to cause the PowerCab to reset. In fact, a high resistance will cause it to be less likely to reset, even in the event of a short, because the high resistance will reduce the current draw.

As someone else mentioned, did they test your power supply with the Power Cab - that would be the first thing I would check. I would also check the resistance between the two rails (with the Power Cab unplugged and locos off of the layout). It should be infinite, if not, you could have a short between the rails or in the wiring drawing some current but not enough to reset the Power Cab until you run a loco.

8

the PowerCab has an option to display the current being drawn. enable that to check if there are any low-level shorts in the track without any locos, or other power consuming car (e.g. lights), on the track

it would also indicate the amount of current drawn by loco just before shutting down

9

I forgot about that feature. That would be the first thing to check.

10

And to aid the OP into setting up that feature on his Power Cab in the event that he’s not familiar with how to do that…

  • Press PROG/ESC 5x
  • Press ENTER
  • Press 1 for SHOW TRK CURRENT
  • Press ESC 2x (to get back to operating screen)

It is a very handy feature. I use it often for monitoring current draw before or after a motor installation.

Tom

11

Hello All,

All great suggestions.

Here’s a really basic one…

Have you tried resetting the system to the default factory settings?

I have the Wireless ProCab system so my instructions are different than yours.

Sounds like tstage has access to that info if you can’t find your manual.

Keep us apprised.

Hope this helps.

12

Good suggestion. Actually, all of us Michiganders who live south (under) the Mackinac Bridge are considered trolls!

13

I was assuming but maybe I shouldn’t, is the loco on this high resistance track when the PC resets? No, it is not.

14

Good question. I don’t run more than two at a time. Once this failure happened, I tested my other sound locos and had the same result. My non-sound locos can receive a few more speed increments before resetting.

I’ll throughly clean this and possibly re-solder. Thanks.

15

Hello All,

So, with some minor differences, it happens to all the motive power, sound or no sound.

HMMMMM!!!

This is a real head-scratcher! [banghead]

OK, other simple checks…

The batteries in the cab?

As this is a tethered connection have you tested the cables?

Inexpensive; less than $30.00, testing units are available at hardware stores and home improvement centers.

Some have a remote terminator so you don’t have to pull the cable to have access to both ends of the cable at the testing unit.

Simply plug one end of the cable into the remote terminator and the other end into the testing unit.

Another, more extensive diagnostic, is to take the entire pike (layout) out of the electronic equation.

Make a test track out of two pieces of flex track or the sectional equivalent to make an approximate run of 5- to 6-feet. You can attach this to a 1" x 4" board or piece of plywood, or if you have the space directly on the pike.

You’ll need this track length to get the motive power up to “failure speed” with enough room for them to stop, or- -you catch them.

Disconnect the feeder wires from the PowerCab Power Panel to the bus and attach them directly to the section of isolated track. You might need to make a temporary set of jumpers for this.

Try running a single sound locomotive on this test track and see if the same problem occurs.

If it still happens then it’s probably something in the cab/power panel/power supply chain.

If the unit runs normally on the isolated test track then it’s in the trackwork/wiring.

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16

What do you mean by “finding heavy resistance on one rail?”

Is there resistance between one rail and the next section of track? Is that rail on the point end or the frog end of the turnout?

You mentioned having blocks. Can you still control them? Can you shut off one block at a time to possibly isolate the problem?

My guess is that you have a low-grade short circuit that is enough to draw some current but not enough to trip the breaker. When you add a bit of current for locomotives, it crosses the threshold and trips the breaker.

17

what does the current meter report?

18

Hello All,

OK, grasping at straws here…

The NCE Wireless PowerPro manual, recommends installing the non-powered Cab Bus Fascia Panel UTP “upside-down” or PCB side “up” so dust and foreign particles don’t contaminate the connections.

Try removing the PowerCab Power Panel and cleaning it with canned air over the entire PCB.

Remove the connectors and blow into the female connectors to force any contaminants out of the connectors rather than blowing on the outside forcing them deeper into the recesses of the powered PCB and related connectors.

Keep us apprised of your progress.

Hope this helps.

Post Script:
My father-in-law was a research scientist. He used to say that a negative result will send you down a path to success sometimes faster than the result you expected.
J.J.D.I., H.T.H.

19

The PC doesn’t have a battery AFAIK…If it does, mine is still good.

still waiting to hear if this shut down reset occurs on the high resistance track.

20

Hello All,

Sorry, I didn’t know.

I’m using the NCE Wireless PowerPro with a separate command station/booster.

The wireless cab uses 4 x AAA batteries. I thought the cab might have batteries.

I apologize for the confusion.

Hope this helps.