LNERGE Posted January 19, 2020 Share Posted January 19, 2020 I've been dabbling with asymmetric braking with some success though I'm probably not using it as intended. I simply want trains to stop when the route ahead is not set or the section occupied. I achieve this already with a last resort dead section between conflicting routes but wanted something more elegant. I'm not bothered too much where the train stops at this stage. I only have two loco's fitted with Zimo chips that work successfully so far and they have been quite happily following a non abc loco round the layout that has been set to run slower than the abc fitted loco's. I fitted an 8 pin Zimo chip to another loco and set CV27 to 1 expecting it to happily join the queue like the others but instead it became quite wild in its behaviour. When it encounters an abc fitted section of track it runs at a constant speed and no longer responds to the controller. I'm sure you can imagine the chaos caused by a wild loco with three trains already running on the same track.. I have run the 8 pin Zimo chip fitted loco by itself with the same wild results. With CV 27 set to 1 it will not move off forwards if it has been stopped in an abc section and the signal restored in front of it. I will however drive away from the signal. Doing the same thing with CV27 set to 3 the loco won't move at all. This is what I expected to happen.. Is there something else I need to adjust to make this loco with the 8 pin chip behave itself instead of running at a constant steady speed and not responding to the controller in an and fitted section? Link to post Share on other sites More sharing options...
RAF96 Posted January 19, 2020 Share Posted January 19, 2020 It sounds like the decoder is seeing the asymmetric signal as plain DC and it is causing DC runaway. Does ADCC work if you disable DC running in CV29. Link to post Share on other sites More sharing options...
Nigelcliffe Posted January 19, 2020 Share Posted January 19, 2020 In addition to post by RAF96, what are your brake zones made from ? Commercial Lenz units or DIY with diodes ? If DIY, are they fast-recovery diodes ? If normal recovery diodes, then the DCC waveform could be distorted. There are other settings in the Zimo manual for diode sensitivity which may be useful. Bottom of it all, it could be a fault in the decoder, so after some careful testing, you may wish to contact either Zimo's technical support, or the supplying retailer. Link to post Share on other sites More sharing options...
LNERGE Posted January 19, 2020 Author Share Posted January 19, 2020 DC is disabled for sure and the thing is wild.. The diode units are home made and work well with the other Zimo chips. Link to post Share on other sites More sharing options...
Nigelcliffe Posted January 19, 2020 Share Posted January 19, 2020 45 minutes ago, LNERGE said: ..............The diode units are home made and work well with the other Zimo chips. That's not quite addressing the point I made. A distorted waveform might be OK for one decoder, but "over the edge" for another. 1 Link to post Share on other sites More sharing options...
LNERGE Posted January 19, 2020 Author Share Posted January 19, 2020 I'm looking into the diode issue. To further complicate things each track section passes through a current sensor in the form of a Merg DTC8. This evening I intend to try experimenting with it removed and with it in the same !eg as my abc diodes. I need the DTC8 to be in circuit as they drive the signals. I will order some fast recovery diodes and see if they make a difference. Many thanks for the information so far.. Link to post Share on other sites More sharing options...
Nigelcliffe Posted January 19, 2020 Share Posted January 19, 2020 I doubt a DTC8 is significant - the DCC signal only goes in on a fat wire, making one sharp turn through a coil, before leaving again. Link to post Share on other sites More sharing options...
LNERGE Posted January 19, 2020 Author Share Posted January 19, 2020 I really hope that is the case. The signalling has been working really well for years and I consider it quite robust and reliable. The double track main line is four aspect signalled with just enough headway to run two trains on greens if you are careful.. I have noticed some other locos are behaving oddly. I need to quantify what is going on before I declare I have further problems. Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted January 19, 2020 RMweb Premium Share Posted January 19, 2020 It might just be worth trying CV 27 = 2. We've had problems on our club layout with one or two locos that we cured initially by setting CV 27 = 2. You can always change it back. Link to post Share on other sites More sharing options...
LNERGE Posted January 19, 2020 Author Share Posted January 19, 2020 I have been distracted all evening by a DCC Concepts chip that worked on abc braking for about half an hour on all but one of my abc sections then suddenly stopped working on all of them though still remained functional in all other respects. I'm officially baffled. Link to post Share on other sites More sharing options...
Junctionmad Posted January 20, 2020 Share Posted January 20, 2020 One of the issues with ABC is any wheels shorting the ABC section back to the main DCC can cause issues with unexpected acceleration . So metal wheels on rolling stock bridging the section can cause issues some decoders are better at handling it then others Link to post Share on other sites More sharing options...
LNERGE Posted January 20, 2020 Author Share Posted January 20, 2020 I have noted that. All of my coaches have pickups on at least one bogie and the bridging effect is very noticeable. Link to post Share on other sites More sharing options...
LNERGE Posted January 24, 2020 Author Share Posted January 24, 2020 I called in at Train Tech on the way home from work yesterday afternoon and bought a couple of their ABC1 diode units. They were fitted and everything seems fine on those sections. Even the completely out of control 8 pin chip behaved. Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted January 24, 2020 RMweb Premium Share Posted January 24, 2020 It would be interesting to know what diodes it uses and whether there are any other components. Link to post Share on other sites More sharing options...
Nigelcliffe Posted January 24, 2020 Share Posted January 24, 2020 See my earlier comment about fast and slow recovery diodes. - Nigel Link to post Share on other sites More sharing options...
RAF96 Posted January 24, 2020 Share Posted January 24, 2020 9 hours ago, LNERGE said: I called in at Train Tech on the way home from work yesterday afternoon and bought a couple of their ABC1 diode units. They were fitted and everything seems fine on those sections. Even the completely out of control 8 pin chip behaved. The effect of qualified British design and manufacture... ...nice how David Palmer’s T-T stuff just seems to work exactly as advertised, no drama. Link to post Share on other sites More sharing options...
jpendle Posted January 24, 2020 Share Posted January 24, 2020 1 hour ago, RAF96 said: The effect of qualified British design and manufacture... ...nice how David Palmer’s T-T stuff just seems to work exactly as advertised, no drama. As opposed to making one yourself, as the OP did? I'm don't see why 'British' has anything to do with, I would wager a Lenz BM1 would work just as well. Regards, John P Link to post Share on other sites More sharing options...
LNERGE Posted January 24, 2020 Author Share Posted January 24, 2020 I decided to buy some abc braking units so I had a benchmark for how things should behave and to help assess if the project was viable. I have ordered a selection of fast recovery diodes for further experiments. They just seem to be taking an age to arrive. The conclusion so far is the system will work on my railway. I’ve always steered clear of anything with electronics involved. I find myself having to understand how some of this stuff works etc. Yesterday I spent the day sourcing a serviceable gear train and clutch for a point machine, transporting it to site and swapping out errant parts to fix a fault etc. Once done and tested I moved on to terminating a 37 core cable and testing. My level of concentration after that lot and a two hour drive home doesn’t lend itself to learning about new stuff. Hence the questions. The steering towards fast recovery diodes was a master stroke, thank you. I have a few hours to play this evening then I’m off out to renew a point on the GN mainline and the commissioning of a new section of line/track circuits/signals and interlocking. Hopefully the diodes will will arrive tomorrow so once I’ve had a snooze I’ll hopefully make some more progress. Link to post Share on other sites More sharing options...
LNERGE Posted January 24, 2020 Author Share Posted January 24, 2020 The background sounds we’re pretty good for my 12 inch to the foot work yesterday.... this was shuffling units about for a few hours.. 1 Link to post Share on other sites More sharing options...
RAF96 Posted January 25, 2020 Share Posted January 25, 2020 On 24/01/2020 at 16:45, jpendle said: As opposed to making one yourself, as the OP did? I'm don't see why 'British' has anything to do with, I would wager a Lenz BM1 would work just as well. Regards, John P I made my own 5-diode modules years ago. The schematic cn be found in my gallery. Link to post Share on other sites More sharing options...
LNERGE Posted February 2, 2020 Author Share Posted February 2, 2020 The fast recovery diodes finally arrived yesterday morning. I ordered them back in the 20th and had given up hope and reordered another load from cpcfarnell. Of course both deliveries turned up at the same time.I They have certainly cured the problem and all is well. Many thanks for being pointed in the right direction. 1 Link to post Share on other sites More sharing options...
LNERGE Posted February 9, 2020 Author Share Posted February 9, 2020 Things are settling a bit now... One thing I have noticed issue some loco's react to the signal they are passing. The first wheel touching the next track circuit restores the signal.. This in turn causes some loco to slow despite some where are exposed to the full dcc signal.. Link to post Share on other sites More sharing options...
LNERGE Posted February 18, 2020 Author Share Posted February 18, 2020 It has been a voyage of discovery to say the least. As a test for each loco fitted with an abc chip I have run a very slow train and set the loco on test to run faster. I fitted Cravens with a new chip and it refused to stop in just one section. It behaved perfectly in all others.. I think I will need to fit an override push button to some sections as I need to pull right up to a signal to be able to set back into sidings etc Some non abc loco's do some odd things. I have a Hornby tts fitted 31 that appears to slow down when abc is effective but won't stop. It is still controllable however. What I could do with now is some gizmo that you can place in the rails with pretty lights that changes state when abc is present or not <g>.. Link to post Share on other sites More sharing options...
LNERGE Posted February 22, 2020 Author Share Posted February 22, 2020 I have a couple of locations where the block joint is quite close to the signal. The next track is a track locking track through S&C and that is included as the overlap for the signal in rear. If a railcar is propelling trailer first it restores the signal to danger before the power car gets to the full dcc signal. It is most apparent when the railcar has been checked at the signal and has not picked up enough umph to carry it over the block joint. If the power car is leading all seems ok. It looks like I will have to fit last wheel replacement to the signals to overcome this. Any ideas? Link to post Share on other sites More sharing options...
LNERGE Posted December 25, 2020 Author Share Posted December 25, 2020 I'm having a problem with a different manufacturers decoder. Everything so far has been with Zimo decoders. I thought I'd try another manufacturer that offered a plug in stay alive facility. I can get the loco to stop at a signal. If I take it off the track and turn it round and reverse the controller so it is going the same way as when I started it fails to stop. Cv27 is set to 1. Am I missing something? Link to post Share on other sites More sharing options...
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