orton hall decoder fitting

[Yelrow]

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[Yelrow]

Chrissaf, i understood your diagram, but took it apart, as have no bus. All i have now, is a TT, DCC, connected to a select, with 18 tracks, coming off, all with droppers back to choc blocks. TT, came ready wired, all rails connected. All i did, was to extend wires to fit layout. On testing now, only the bridge, is out of step. All the other tracks, read fine with a meter, and sample locos, travel happily on tracks, until they hit the bridge, which is  out of sync. What i was suggesting, was if i wired the DFJ, to the bridge, and other side to input track, (not connected to layout ), and tested, was that an option. If not, i will have to work underneath, to ensure, all 19 items, sing off same hymsheet. My limited understanding, was that this thingme, compensated/sorted polarity. It appears not to be the case. john                     0

[Chrissaf]

John,

I'm really struggling to understand your description of how your TT and 18 tracks are wired. Is there any way you could produce a drawing. Do you have a scanner. Could you draw freehand on paper then scan it to get an image you could post in the thread.

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My best guess at what I think you are saying, is that everything from the input track onward is isolated into its own little layout domain. That is to say, the TT itself and the 18 outlet tracks are connected together, but isolated from the main layout. Is this the essence of what you have described?

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You say that all the tracks around your Bridge track test the same with a meter, but the Bridge track is Reversed compared to them. I think you are suggesting that you place the DFJ003 between the input track (DCC BUS) and the whole isolated layout section containing the TT and the 18 outlet tracks. Just connecting the whole of that isolated section of your layout to the output of the DFJ003 and connecting the DFJ003 input to the DCC BUS e.g the DCC input track will not reverse the polarity of the Bridge track in isolation. The DFJ003 in that configuration would reverse the polarity of that WHOLE connected section of layout. So not only would the Bridge track rails reverse polarity, but all the surrounding track rails would as well. The Bridge track polarity would still be opposite relative to the connecting tracks.

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Just to expand even further on the DFJ003 as an RLM. The polarity switching of the DFJ003 output relies on the TT Bridge track it is connected to being TOTALLY insulated from the track either side of it (that is to say the input and 18 output tracks) this could be achieved by use of IRJs as documented in last post. If it is NOT isolated and a short circuit develops, the DFJ003 will try to switch the polarity. But if the bridge track is NOT isolated e.g. there is still some electrical path remaining, the cause of the short circuit cannot be removed by reversing the polarity. The short circuit current will build up until the DCC controller detects it and shuts down. Meanwhile the DFJ003 has probably been fried because even after switching the polarity of its output, the short was still not removed.

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So in answer to your comment "My limited understanding, was that this thingme, compensated/sorted polarity." Yes it does compensate for shorted polarity, but it can't do it if the track it is connected to on its output connections is NOT isolated from the rest of the track. In other words, it does its job as it is designed to when wired correctly, but can not compensate for an incorrect installation.

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I say again, if you can replicate the connectivity shown in my drawing, then that should solve your issues.

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If you can find two wires going to your TT Bridge track. Then isolate them. Then check with your meter for any continuity between the Bridge track rails and the surrounding tracks (input track and 18 outlet tracks) and find everything is open circuit (no continuity). Then you could connect the DFJ003 in the middle of those two wires. In other words the ouput of the DFJ003 (shown as Black wires on my drawing) go to the two wire connections going to the TT Bridge, and the input to the DFJ003 connects back to the DCC BUS. But only if the meter test proves 100% that the bridge track is open circuit on all TT Bridge track positions with the surrounding track. If there is any continuity however slight, you will need to find the connectivity and remove it. Again as stated already, IRJs on the input and output tracks should do the trick. If not practicable to fit IRJs, then perhaps consider cutting gaps in the track rails with a modellers razor saw.

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You would, of course, also have to re-instate the DCC BUS connection to the choc blocks connecting to your 18 track droppers.

[Fishmanoz]

John, I can understand most of what you are saying (I have a couple of questions next) and everything that Chris is saying, and I think I can see why you are having some trouble with what he says.

 

Let me take you back to your post at the top of page 2.  You say you have disconnected your track totally from the TT.  Just what have you disconnected to do this?  I know you still have your droppers to your 18 outlet tracks because you then said they measure ok with your meter.  So did you disconnect the motor that rotates the bridge or some track connection?

 

You also say the 18 tracks are ok but you measure the bridge is reversed?  But when you measure a DCC track voltage with your meter on AC, you cannot tell the polarity of the reading, it isn't electrically possible to do so this way, so what do you mean?

 

Next you seem to think your wiring is different to what Chris is suggesting in words and in his diagram because he talks about a DCC bus and you don't have one.  Well just ignore the bus talk.  All he is trying to show is your droppers connected to your choc blocks for the 18 tracks.  So for this part, you have what Chris has drawn.

 

Now can you clear up another thing for me.  Does the TT have a total of 18 track outlets, or 18 outlets plus an inlet which is different, or just 18 outlets?  If just 18, is one of them different and the one you have to connect to your layout?  I ask because it is normal that somewhere on that special inlet connected to your layout, there must be a connection under the TT that goes to the bridge so it gets DCC power.  You should be able to see where this connects to the track, but you won't be able to see where it connects to the bridge unless you lift the TT and look under it.  This is the connection you have to cut.  Once you cut it you will know because your meter will read zero if you put it on the bridge.

 

You cannot go to the next step until you read zero on the bridge.  Once you cut the connections so you have zero, all you have to do is connect the outlet from your RLM (the one in the middle at the top in Chris's diagram) to those cut wires leading to the bridge, either way round will do (doesn't matter which wire to blue and which to brown in Chris's diagram) as the RLM will take care of the polarity.  final step - connect the input of the RLM (bottom left in the diagram) to track or choc blocks with DCC power.

 

If you have got this far, you are done.  You should now be able to read the DCC voltage on the bridge with your meter, and anywhere else on your layout including the outlets.  You locos should run from anywhere onto the bridge, you should be able to rotate the bridge by your normal method, and the loco should run off again.

 

So can you answer my questions up the top please, and tell us how far you have got?  Can you understand everything I've said and does all of Chris's now make sense (forgetting about the DCC bus)?

[Chrissaf]

Fishman,

Perhaps you could help me understand Johns wiring. He says his 18 tracks have droppers connected to choc blocks. OK they may be disconnected at present, but presumably they do or did at some time connect to his DCC controller track output. From your post above, it would appear my use of the term BUS is confusing John.

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Is John's layout in the main relying on track rail DCC continuity, but has droppers in selected locations that in turn are connected via the choc blocks back to the track. A kind of mix and match approach to DCC signal distribution. If that is the case, seems a strange arrangement to me.

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John, if your reading this. Just think of my use of a BUS term as just being the wired connections that eventually go back to the track output connector of your controller. Whether they be actual track rails or separate wires. It is in essence the electrical path that your DCC signals need to take to route between your controller and your decoders.

[Yelrow]

Chrissaf, and Fishy, i really must apologise for  being  in such a muddle, over this, which is basically due to my hands and knees disability. I wear specially constructed appliances on both hands due to arthritus, which make working with screwdrivers, difficult, and now with my knees, silicone injected, makes getting down on the floor, and laying underneath my trains, a job i would prefer to avoid. That being said,  if needs must, so be it. The other problem, is, not being able to comminicate direct, as many of us do, by using the model Rail forum, where we can exchange emails, and  pictures, with ease. I am going to try to photo with the Ipad, and i also have the original drawing of the correct wiring installation, that came with the TT, when i bought it,  secondhand. The french guy, went to extrordinary lengths, to tag every wire, leave and send, all exit tracks, soldered, and supply this plan.. I find it difficult to belive, he did it wrong, so i must somehow,  have  altered something.   I am going for another silicone top up today, after which, i have to chill, so will spend that time trying to work out how to send pictures. I would quite understand, if you run out of patience, but will attempt to photo/draw what i have. Thanks for your tolerance. john

[Chrissaf]

John,

Take as much time as you want. Our bit is easy, just sitting here typing. Understand completely. I'm sure Fishman feels the same.

Chris