Coach lighting problem

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rogtom301
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Coach lighting problem

Postby rogtom301 » Mon Jul 23, 2018 8:31 am

Hi Folks, recently I Fitted the Dapol lighting strips to some of the Dapol coaches, since fitting I am having a problem with the Dapol class68 dcc Fitted locomotive. When the coaches pass over points the locomotive momentarily stalls it’s as though there is some interference going on. It doesn’t happen with any other locomotives.
As anybody else come across this problem, and any suggestions to solve the issue.
Thanks, Rog

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Flashbang
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Re: Coach lighting problem

Postby Flashbang » Mon Jul 23, 2018 10:32 am

Hi
By what you're saying the loco is well clear of the point, but the carriages are still passing over the point.
Are you sure it is not the metal wheels of one or more carriages being able to bridge together the rails at their closest on the frog causing a short circuit? (Only applicable where Insulated frog points are used)

Have you tried turning the carriages around and running them the other way ?
Running just one lit carriage at a time behind the loco to see if the fault occurs with only that one carriage?
Have you checked the wheels Back to Back (B2B) distance is correct?
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Broken? It was working correctly when I left it.

Bigmet
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Re: Coach lighting problem

Postby Bigmet » Mon Jul 23, 2018 10:52 am

I share your suspicions, my suggestions are posted in response to the same question in 'Dapol'...

rogtom301
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Re: Coach lighting problem

Postby rogtom301 » Mon Jul 23, 2018 12:52 pm

Hi, Thanks for your comments , I think you are probably right concerning the frogs.the thing I don’t understand is why these coaches cause the Dapol locomotive to play up and not any others even if these coaches are connected to a different loco.
I’ve not been at this for long so still learning.
Thanks

Bigmet
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Re: Coach lighting problem

Postby Bigmet » Mon Jul 23, 2018 2:24 pm

Here's what I posted against your question in 'Dapol'.

"This could be quite complicated, so several questions.

Did this happen when the same coaches were operated over the same points, but before they were fitted with lighting?

Do you have Peco 'insulfrog' points on the layout, and is it when the coaches are on these that the 68 stalls?

Are any other locos running when the class 68 stalls?

What is your DCC system's rated current output to the track?

What is the current draw of the class 68 and any other locos that are running? It wouldn't be sound fitted by any chance?

What is the current draw of the lighting units used, and the number of coaches fitted with these lighting units?


My educated guess at the cause of what you are seeing. The lighting units have pushed up the sum of the current draws of everything running on the layout to near the limit of what the DCC system can supply. Momentary shorts on the points* cause the power on track to droop, and the 68's loco decoder cuts out on loss of track supply. If the 68 is a sound fitted loco then a quick test is possible to see if this is the explanation. Just turn sound off, and see if the stalling stops. DCC sound typically takes more current than the motor...

*An easy way to see if there are momentary shorts on the points is to watch the coaches in the dark for the little flashes as they run across the points."

These questions were posed to clarify aspects that are currently educated guesswork. If you answer those questions then better diagnoses will result.

rogtom301
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Re: Coach lighting problem

Postby rogtom301 » Mon Jul 23, 2018 4:42 pm

Hi thanks for taking the time, it will take me a bit of time to work out some of the answers to your questions.
Appreciated

rogtom301
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Re: Coach lighting problem

Postby rogtom301 » Tue Jul 24, 2018 8:54 am

Hi Bigmet, answers to your questions, measurements with a ramp meter, system is a BACHMANN 36-504RC DYNAMIS ULITMA DCC SYSTEM witha 3amp output voltage set at 14v.

These are the only coaches I have with pick-ups and the problem happens even if the light strips are not fitted.

Al points are Peco insulated, yes when the coaches are passing over the points is when the class68 stalls, I can have other locomotives running and they don’t give any problems, they never have.

The current drawn has never been above 750ma depending on how many locomotives running.

Each of these coaches are drawing 20ma.

There are sparks occurring when these coaches pass over the points which is when the class 68 stalls, but no other locomotives are affected.
The classs 68 came DCCfitted and its the only chip of its kind on my track.

It’s looking like it’s the points that are causing the problem, but why only on the Class 68 is what I can’t understand.
Looks like I will go back to fitting the train tech light bars and not have pic-ups if that’s going to stop it.

Many Thanks

Bigmet
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Re: Coach lighting problem

Postby Bigmet » Tue Jul 24, 2018 1:38 pm

Good work. What that says to me is that the decoder in the class 68 is very sensitive to momentary dips in track power.

My 'quick and dirty' solution to restore reliable running would be to try a proven good decoder type in the model; my usual choice would be a Lenz standard, but whatever you are presently using in a similar loco mechanism that doesn't exhibit this problem is worth trying.

You could complain to Dapol, that the product is substandard in this respect compared to competing products on your layout and what would they like to do about it?

Some would suggest fitting a 'stay alive' to the loco, but I see that as a sticking plaster to get around a problem that is fully preventable.

Longer term, maybe next layout, go all live crossing (Peco speak = electrofrog) to remove this potential problem source.

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Flashbang
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Re: Coach lighting problem

Postby Flashbang » Tue Jul 24, 2018 3:27 pm

Remove the two metal rail joiners (Fishplates) on the points Vee rails ends and replace them with Insulated Rail Joiners. Then add two new rail feeds (if needed) after the IRJs, one of each polarity. Doing this 'fix' stops both rails at their closest being of opposing polarity and only the live directions rails are powered! But before doing this I would check each carriages wheels B2B is set correctly.
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Broken? It was working correctly when I left it.

rogtom301
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Re: Coach lighting problem

Postby rogtom301 » Tue Jul 24, 2018 7:10 pm

Thanks folks, you’ve given me a lot of food for thought.
Appreciated :D

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End2end
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Re: Coach lighting problem

Postby End2end » Tue Jul 24, 2018 7:32 pm

Flashbang wrote: I would check each carriages wheels B2B is set correctly.

The back 2 back gauge is a tool I use OFTEN. Even on new rolling stock.
Get one. It's invaluable!
https://www.ebay.co.uk/itm/DCC-Concepts ... SwiVhZw8iI
Possibly cheaper elsewhere.
Thanks
End2end
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RAFHAAA96
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Re: Coach lighting problem

Postby RAFHAAA96 » Wed Jul 25, 2018 8:52 am

Sparks across the points, could well be B2B or a need for IRJs if its only one point.
Rob
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Bramshot
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Re: Coach lighting problem

Postby Bramshot » Wed Jul 25, 2018 10:27 am

Ditch the light bars and make your own using led strip. Much cheaper and you can add some resistors to get the current draw down. I use these with Dapol coaches, you can buy the plugs to connect to built in sockets.

I also have Bachmann Dynamis Ultima (but mine came with a 5A power supply) and can easily run 5 locos and 17 illuminated coaches simultaneously. Plus sound.

What decoder is in the 68? I have found the DCC23 as fitted by Dapol to be a bit prone to forgetting what it was doing during ‘power cuts’.


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