Dcc wiring

[Barking wag]

Please help, I am converting my layout to DCC, track and rolling stock including locos 35+ years old But chipped and working. my layout is in effect 3 concentric ovals. The issue is wiring. When I attach the 3rd concentric ring to BUS wire there is the power stops completely when I disconnect droppers from the 3rd oval the power flows to the two outer ovals And the trains can run. All track is Hornby. Any advice on where to start looking to overcome this problem.

[RDS]

Hi Barking wag and welcome to the Forum

It seems that you are creating a short, when you connect the 3rd Oval, which tends to suggest you have the rail connections crossed for that one.  Can you tell us what other BUS wires you have connected and where they go to.  

 

Another thing that is strange though is that you say, "when I disconnect droppers from the 3rd oval the power flows to the two outer ovals".  Does this mean there is no power to the 1st Oval?

[Chrissaf]

Barking wag.

As RDS has stated, if connecting a dropper at any location causes the controller to trip. Then the dropper wires you are connecting are reversed. In a BUS system, if ANY one dropper pair are reversed, a short circuit will occur.

[Barking wag]

Thanks both, I have double checked after your post but can confirm that the colour coded dropper wires lead to the same coloured bus wire, the bus wires are fed from control unit. I assume it must be a short but when I turn the power on there does not appear to be a short as the on light stays constant As opposed to when I have shorted previously.

to confirm RDS when I disconnect droppers there is no power to the inner oval.

thanks again.

[Chrissaf]

You're checking the wrong end. It will be where the droppers connect to the track you should be checking. You haven't told us how you are attaching the droppers to the track.

.

Are they soldered directly to the rail?

Are you using Hornby R8242 Power Clips?

.

If you are using R8242 power clips and you then place the clip on the opposite side of the track relative to any other power clips you are using, then you have to reverse the A&B wires on them.

.

Take a small wagon and place a bit of tape (masking tape will do) on one side of the wagon. Let's now give this side of the wagon an arbitrary colour label, let's say Red.

.

Now push the wagon around the track and through points without ever taking the wagon off the track. Now whenever you stop the wagon at a dropper location, make sure that the rail on this nominated Red side of the wagon ALWAYS connects to the same colour dropper.

.

You may find certain sections relating to DCC power of my 'Getting Started with Track Extension Packs' useful. Also have a look at Figure 12 in my document that explains why there are situations where the A&B wires of track power clips should be reversed.

[Barking wag]

Many thanks for the link and very clear. I have a bus wire running in a two pronged star pattern underneath layout. If I have wired around the points do I still need point clips. The droppers are soldered, connections are good or appear. Thanks for your help.

[Chrissaf]

If you have droppers on each side of each point (turnout), then you do not need digital point clips as well. But if you do include them as well as droppers, then they will provide a direct electrical path from the fixed to the moving switch rails. This can be beneficial, as the electrical reliability of the DCC signal passing onto the moving switch rails is then not totally reliant on the physical 'side of rail' contact between the fixed and moving rails. These 'side of rail' contact areas will eventually become dirty and tarnished affecting the ability to transfer electrical current between rails. Thus the inclusion of the point power clips can eliminate or at least alleviate this potential electrical weakness.

[RDS]

@Barking wag

As I asked in my first post, please advise us where your droppers are positioned.  

[Flashbang]

Hi

 

Here is my 100% foolproof dropper to bus wire checking method...

Take a four wheeled wagon and along one long side place a piece of tape - Masking tape, Insulating tape or even a band aid plaster etc it doesn't matter so long as it sticks temporarily.

Now place the wagon onto the rails directly above a known correctly wired dropper. The taped side being directly over say the Red dropper wire.

Important.. Do not remove wagon from the rails while checking is in progress.. Without lifting the wagon off the rails and by finger push the wagon around the tracks, use the points to pass loop to loop and track to track - Remember don't lift it off the rails.

Wherever a dropper is connected to the rails the taped side on the wagon must have a red dropper wire connected to the rail directly below that side and of course the opposite rail would have a Black dropper. Below check their connection to the main Bus pair - Red dropper to red bus wire and Black dropper to black bus wire.  

 

Note: I have used Red and Black in my text, but the two wire colours Bus and all Droppers are your choice, but they should be two different insulation colours. e.g. Brown and Blue. Red and Black. Green and Yellow etc

[Flashbang]

Example of an old four wheeled wagon on testing duties... 

http://i190.photobucket.com/albums/z311/Flash_bang/P72_zpsvlgwfvsm.jpg