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Old 07-07-2018, 09:36 PM   #1
mark1
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I'm having ongoing problems with my DCC layout. When one of my DMU sets is travelling, at a completely random moment, usually when a second train is running, another of my locos starts up, usually at high speed. There had been problems with the lighting of the DMU and I wondered if these problems were connected. However the DMU lighting has now been put right but the false starts are continuing. The false starter locos are programmed for DCC only. My layout is medium sized (double track oval with some sidings and nearly 20 points) and is controlled by Gaugemaster Prodigy Advance.

Is it possible that my Prodigy Advance system ( bought second hand over ten years ago) is no longer able to cope? Any other suggestions?
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Old 07-07-2018, 09:37 PM   #2
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Only 2 things I can think of would be to reset the decoder and re-programme to see if that helps or, replace the chip in case it's faulty.

EDIT: One more thought, get the multimeter out and check for any continuity issues. I recently had an issue with locos shorting over a point and couldn't work it out! End result? I'd put the point motor in the wrong way round!

Unscrewed it, spun it 180 degrees and switch the feeds to the bus wire and now it's fine.
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Last edited by ScottC; 07-07-2018 at 09:41 PM.
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Old 07-07-2018, 09:48 PM   #3
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Runaways will usually be a result of a loco picking up a corrupted Dcc signal.
Three things to do:
Clean all the track and locos.
Change CV29 to disable DC running.
Fit ‘snubbers’ on each end of the bus wires to wipe out interference.
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Old 08-07-2018, 06:10 AM   #4
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It might be worth testing the DMU on DC to make sure that DC is actually disabled.

Beyond that make sure that your wiring to the track is sound and that you have used fat wire. If a second train is causing interference it will be due to the current the second train is using being large enough to cause voltage drop and therefore interfere with the DCC signal getting to the DMU.

Also look out for anything that might cause momentary shorts as well (Streamline Insulfrog points, iron filings in motor/behind wheels, changes of grade, etc.)
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Old 08-07-2018, 06:38 AM   #5
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Two suggestions....
Try to isolate which loco is causing the problem as opposed to which loco is affected by the problem, by running a scenario trying to replicate the event, then remove the loco you think may be the culprit. Repeat until you find the event does happen with a particular loco on track but never happens with it off track.
Secondly check to see if the GM PA2 can have its firmware updated.
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Last edited by RAFHAAA96; 08-07-2018 at 06:39 AM. Reason: Minor errors - missing word and typo
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Old 08-07-2018, 09:43 AM   #6
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Could it be the capacitors on the trains themselves that are interfering with the DCC signal that could be the likely cause of DCC signal issues? When I started in DCC, everything had to be hard wired in and it was the done thing to remove these capacitors for this reason, but since the 8 pin plug came in and the many other DCC plugs and sockets, no one seems to remove the capacitors? Could this be the cause of the DCC signal issues?
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Old 09-07-2018, 01:25 PM   #7
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Thanks everyone for your ideas. Checking CV29 shows that DC running is disabled on the false starting locos. The loco which might be called the culprit is the DMU I mentioned. It has been back to Hattons who fitted it for sound. They checked it carefully and found nothing that might contribute to other locos false starting.
Even with the DMU and one other loco running, the AC voltage at the rails is 14v so it doesn't look like voltage drop. In fact my wiring is probably heavier duty than is needed.
I will investigate "snubbers". What are they?
The longer the problem remains unsolved the more suspicious I am of my Prodigy Advance system but I hesitate to replace it unless I know it's faulty.


Anyway thanks again. All further suggestions gratefully received.
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Old 09-07-2018, 02:10 PM   #8
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Link to ‘snubbers’:

http://www.brian-lambert.co.uk/DCC.html#On
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Old 23-08-2018, 08:37 PM   #9
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Thanks for this link.

I see that snubbers should be fitted to unconnected "ends" of the bus wires.

The ends of my bus wires are connected directly to my track. I have no unconnected ends.

Does this mean either:

1 . I have no need of snubbers.

or

2. I should fit snubbers at any convenient location where I can bridge the bus wires.
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Old 23-08-2018, 09:16 PM   #10
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They don't need to be connected to the ends, but ideally as far as possible away from where the bus is connected to the booster.
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