I am hoping that someone may be able to offer me a solution to my problem. I am building a new DCC based layout, built with C track and including some 30 turnouts. I have used the 74462 decoders and 74491 motors in the turnouts. I am using a YaMoRC YD7010 DCC Controller, although I also have a Roco Z21 (Black) controller, and the issue remains with either. My layout is L speed 4 x1.2 m and 3 x 2 m.

My issue is intermittent problems of the turnouts not switching when commanded. This is not restricted to specific turnouts but across the whole layout. Any one turnout will be working one moment and then not the next. However, if I test a non-working turnout connected to the programming track it will work perfectly, switching on command, and the CV values are all correct. I have tried setting CV8=8, as suggested in some other thread posts, but that has not worked. If I then replace the turnout back onto the main track it will either still not work, or work once and then fail. I don't understand why a turnout will work on the programming track, and then not work on the main track.

I am currently laying down the track and wiring it up, so at present there are no other sensors or accessories connected to the layout. I have used 24/0.2 wire for the track power feed, and have between 16.5 and 17.2 voltage on track and at the turnouts when I test with my multimeter. I have power feeds to the track piece adjacent to the turnouts.

My layout building at a standstill till I can resolve the issue and I am not sure the best way to move forward. I understand from other posts on this and other forums that others have suffered from similar problems and thus any advice or suggestions as to how to resolve the problem would be most welcome.

Many thanks

Hi Peder

Thanks for your post

yes locos run OK.

Alex

Hi Jean
Many thanks for your post.
Just to be clear in my mind, are you saying that the 74491 and 74492 motors were the ones giving reliability issues, or that the 74491 and 74492 motors are the motors that have resolved the issues. It's just that my motors are all 74491's. All of my turnout decoders are the 74462.

Many thanks

Alex

Hi
That was one of my thoughts, so I switched out the YD7010 Controller for the Z21 controller and got the same results, so I dismissed that. I also suspected that it could be my wiring so ran some wiring straight from the controller to one short section of track, with two sets of turnouts attached. The turnout nearest the power supply didnt work, as usual, but the second turnout worked perfectly. Both worked perfectly on the programming track.

Dear Alex -

Could it be track geometry? I had a problem once with a very simple, C-track layout (i.e., 3 rail) consisting of a straight section of track with a reversing loop at each end (connected with a turnout; a dumbell-shape). It was fed with power and control signals from a MS2+gleisbox at a single connection point.

I found that unless I put isolators (74030s, the red things) in the reversing loops somewhere, I could not run locos properly (they would stutter and run slowly). My guess was that there was interference with the control signals going both ways round the reversing loop. If you have a similar geometry (or one that leads to control signal interference), that could be the problem actuating your turnouts on the layout, as opposed to on the programming track.

(I would like to know why isolators are required for this track geometry, but that probably is a separate forum topic.)

Osoraku

Connect the non-functioning switches to the programming track and ensure they are working properly that way. Then swap the power to the programming track with the regular power output and see if they continue to operate properly. That should indicate whether you have a wring problem or a controller problem.

Thanks, I will try that tomorrow morning

Alex

Another thing to check. I just operated a turnout while having a multi-meter connected to the track. It showed an increase in both dc and ac voltage though achieving a stable reading with the center knobs was very difficult. If the command is not getting to the turnout it will not operate.

Hi Alex/All,

See below article on 74491 mod.

74491 C-Track Mod

Again everyone who posted, thanks for your help and interest.

I am pleased to say that I have made good steps forward. On 8 of the turnouts, including 5 that were causing issues, I removed the decoders from the turnouts and wired them to an 8 way accessory decoder for solenoid drives, (YD8008) and these appear to be working perfectly (for now...). This weekend I will rework some of the other troublesome turnouts and short out the microswitches, and see how those work.

Once again, your help has been very much appreciated

Alex

Hi David

Thanks for your post. I am not saying that any of the decoders are faulty, but my problem was that when installed on the main track, with the decoders fitted, sometimes the turnouts would work, sometimes they would not; however as when attached to the programming track they worked. I was getting the same issues with both my Roco Z21 and my YaMoRC YD7010. It was also random as to which turnouts worked and which didn't.

I thought that there could have been a problem with my wiring, but I was able to replicate the issue with the turnouts powered directly from the Command Control ( i.e. not via the bus)

Marklin had already replaced a decoder and motor that I had suspected was faulty, but now I am not so sure it was, but was simply not working properly at a particular moment. It was very frustrating but I could not get to the bottom of the problem - some people were advising that the motors were the likely problem, others saying it was the decoder. I am waiting for a response from Marklin as I emailed them specific details.

I accept that the motors and decoders may probably work perfectly with the Marklin control centre, but I didn't want a Marklin one, and they are supposed to work with any DCC control command. Clearly there is an issue of some sort - too many people have reported such issues.

I really didn't want to have to discard the decoders - its a lot of work + cost, plus an additional 100 or so wires to install, but all I wanted was a reliable system to allow me and my grandsons to run the trains without the problems of having turnout failing to turn when commanded!! So far the suggested resolution has worked.

Hi Alex,

I wish I would have seen your post sooner. I had the same experience with 2 of my Marklin C-Track turnouts with Marklin decoders. Initially They worked fine with the ECoS Command Station and RocRail Software, but then two of the turnouts would not respond occasionally. As time went by, the problem seemed to present itself more often. I troubleshooted just as you did with the programming track & main track and even installed different decoders in the turnout. All seemed to work well for some time - then the problem presented itself again with the same two switches. It was very frustrating as you know. I finally removed the decoders and installed an accessory decoder like you did. I used the Marklin K83 and a Viessmann 5211 (Marklin K 83 equivalent) since I had them already. Since then I have not had a problem with the switches responding to the command. I never discovered the cause of the issue but happy that it is gone.

Hi Rich

Thanks for the post and your story. It is an odd issue, and yes incredibly frustrating, and disappointing for the grandkids when things wouldn't work properly. I think that if it hadn't been for the kind folk on this and other forums, with their suggestions and encouragement, I would have gone mad!! I dont mind things going wrong, but I like to know why.

I am glad to hear that your turnouts are working well now, hope mine will also do the same - will find out over the coming week.

Thanks for the post and interest

Alex