Reverse loop problems

[Porkster]

I have just installed two digitrax AR1 reverse loop modules. When the loco crosses the IRJ on leaving the loop, the loco stops and then after a short delay continues. It's as if the module is too slow in its operation. The same thing happens on both loops. Judging by the clicking sound the module sounds like a relay style as apposed to solid state, is the part of the problem? Can anyone offer any ideas please.

[Flashbang]

Hi

If the Digitrax RLMs are relay based then often these will be too slow in operation thereby causing the main DCC system to "see" the short occurring before the RLM has had chance to remove the short.  

 

What DCC system are you using?  

 

If the RLMs you have are brand new I would contact the supplier and ask if its possible to arrange a return and either a refund or an exchange to a better style of RLM thats all electronic.    

 

Good luck.

[Porkster]

Flashbang, thank you for your advice. I had assumed the digitrax unit would have been solid state so was quite surprised and very disappointed to find it was relay driven after I had installed them. I only purchased them this morning. I am using a NCE procab system. So you feel fairly confident that speed of operation may be the problem. I was also told by the hobby shop that I did not need to wire it via a circuit breaker, is that correct? 

[Britannia Builder]

I'm using the Hornby RLM with eLink and it works very well, but it also makes a faint click which suggests that it has a relay in it.

 

Regards, John

[Flashbang]

Hi

 

Your problem is going to be the low'ish current the PowerCab outputs compared to many DCC systems. Nominally the PowerCab is around 1.5 Amp depending on the power supply provided with the kit.  

Doesn't the Digitrax RLM have user adjustable tripping settings?  If so, make sure it is towards the lower end of its range of setting, then retest.

 

All electronic RLMs .... The Lenz LK200 is all electronic and should work ok.  The PSX-AR is another all electronic RLM.  Also well worth considering is using a Dual Frog Juicer as the RLM. (Cheaper than the previous two!) 

But best advice is to speak to the supplier who should really know their products and what they work with etc.

[96RAF]

My initial thought was could the errant device relay be slugged against false trips.

[Chrissaf]

Tam Valley (I use them) are all electronic. They have two current settings, 4 amp and 1.7 amp. Most RLMs are not very well suited to operate with low current controller power supplies e.g less than 2 or 3 amps. The Hornby RLM is one exception, it has a switch setting to suit the 1 amp power supply used with the Hornby Select and eLink.

.

My Tam Valley's are configured as 1.7 amp with the Hornby 4 amp power supply. The switching is so instantaneous that my sound locos don't even hiccup (sound-wise) when crossing the boundary.

.

EDIT: FlashBang is correct. According to the AR1 Installation Datasheet, it is trip current adjustable down to 0.25 amps. As FB suggested and I concur, adjust the trip down to a low trip current and test again, then turn up one turn of the adjuster at a time and retest to see if there is an optimum adjustment setting that suits your layout better.

[Porkster]

The procab system I have is feed by a 5amp power supply. I have set both RLM's to their lowest settings but it makes no difference, they both respond in exactly the same way. One chatters quite badly on the low setting so I have had to tweet it up a little to stop that. It does this regardless of whether a loco is on that section or not. Any thoughts as to why this would happen?

Digitrax say that the wiring needs to be quite grunty to handle the "short" current. I have 2 X 0.5mm droppers to one section about 1200 long and 3 X 0.5mm to the other that is about 1600 long. Both come off 1.5mm separate bus sections.

My loco's are sound and when the exit the loop section they stop at the IRJ, stop, pause, then continue without sound. This suggests to me that they loose power in this process and the pause is the natural way that these sound loco's start up. So why is it loosing power? Is it the relay switching process being just too slow?

digitrax also suggest that I sound not have the IRJ adjacent to a point as the resistance of the rail joiner to the point restricts the fault current. One of mine is right after a point both ends, therefore should I solder the fish plates to those points to help reduce the resistance? 

As you can see, I am struggling here and am worred that if I go an purchase a couple of electronic RLM will they too fail me.

[Fishmanoz]

Seems to me they aren't fit for purpose on your DCC system. I would return them under warranty on that basis and purchase a couple that are from the recommendations above.

 

By the way, your dropper/bus system is far from best practice.  When you see dropper size recommendations, they are normally on the basis that the droppers are not more than 300mm long. With the lengths you have, you are effectively running a complicated bus with some of its wiring under size.

[Porkster]

Hi Fismanoz, I thought my bus and droppers we ok? I have devided the layout into 3 zones, each protected by a circuit breaker. Each section has a 1.5mm bus running its length approx 6 metres, 4m and 2 m. every rail has a 0.5mm dropper about 400mm long down to the bus. Is this not good enough? Cheers Porkster

 

ps each day I connect up the rails I have installed and checked that the wiring is correct and that the loco's run. Apart from the reverse loops, everything seems ok to this point.

[Flashbang]

Hi

Sorry for the confusion.... I miss read your reply to one of my posts!!.. I read "PowerCab" when in fact you have a "ProCab" DCC system so the available current to track is much greater.

Have you tried setting the RLMs trip current to around 2/3 the way of its travel towards maximum then retest with the ProCab? You may even then have to 'tweak' the setting a little one way or the other to obtain the optimum trip current setting.

 

[Woody52]

Hi Porkster, are you sure you have turned the adjustment screw in the rite direction. The AR1 is a great unit and adjustable over a wide range. The fact that you are getting chatter would sugest that you have turned it in the wrong direction. Turning it all the way in the oposite direction should cure the problem, then turn it slightly back and test. Keep doing this until it stops reversing then again turn it back a little. There is a sweet spot where it reliably reverses and doesn't make any noise other than maybe 1 click when it reverses. Don't try and do both at the same time.

Peter

[Rog RJ]

You haven't got the two reversers connected to the same loop, have you?

[Fishmanoz]

Sorry Porkster, now I get it, it's your RLs that are 1200 and 1600, not your droppers, my mistake.  What you have sounds fine.  And just to make sure - your longest train is shorter than 1200?

 

And from subsequent posts, looks like more tweaking to try before giving up.

[Porkster]

Thanks guys for all your help on this one. Fishmanoz, yes, I measured my longest train and 1200 on that particular track will be fine. Thanks for your thoughts Rog, but no the two RL's are quite separate. Hi, Peter, I have tried with the pot hard up and hard down but apart from the chatter on one RLM when hard down it did not seem to make any difference. I will however try again along the lines you have suggested. The more I loose sleep over this problem, the more I am starting to think that maybe the RLM's are in fact working fine and the problem is with my sound loco's. By that I mean maybe the two are simply not compatible. The sound loco's have a "routine" they go through in starting up before moving forward (or backward). This routine take quite a few seconds. They go through the same routine regardless of whether the sound is on or not. So when they go over the IRJ they very temporarily loose power ( and sound) so the loco appears to be sitting there doing nothing while it goes through its start up routine albeit without sound. I believe that a standard dcc loco would simply keep going as it would not have the start up routine. Those of you with sound loco's will know what I am talking about. I might try altering the cv's to negate the start up and see what happens. Presumably an electronic device would work faster and prevent this problem from occurring.

?? Any thoughts, cheers

 

 

[96RAF]

Interesting that your sound locos do the delay thing with sound on or off, as Hornby TTS steam locos will delay start to clear cylinders only with the sound on, else they take off straight away upon throttle up.

[Porkster]

Hi Raf, that's interesting, I will check that out again. I thought it was more a factor of the controller rather than the loco, but to be honest I really don't know, I am on a very steep learning curve. Cheers

[Porkster]

Oh and I meant to add mine are Hornby TTS

[Fishmanoz]

The point of an RLM is that it can detect the phase reversal present as a loco or rolling stock wheels bridge across the IRJs in the isolated section of an RL and reverse that phase difference back to zero before the controller shuts down due to resultant high current drawn.  Given the controller doesn't shut down, and therefore continues to put the DCC signal to the track, either directly or via the RLM in the isolated section, then the decoder and hence the loco should continue uninterrupted, doing what it was last instructed to do until a new instruction is received.  The decoder doesn't respond to phase, only to the receipt of power via the DCC signal and the signal packets encoded onto the DCC signal that contain the decoder's address.

 

It is also possible that a packet is being transmitted right when the phase reversal occurs and is corrected, leading the decoder to received a corrupted packet and behave unpredictably.

 

If the RLM is behaving properly, none of this should occur, the phase correction being so fast that it goes unnoticed by the controller and the decoder and the loco just continues on, including any sound.  If this isn't happening, and the current setting in the RLM cannot be adjusted to make it happen, then the RLM is not fit for purpose and you should have the right to return it under warranty.

[Porkster]

I set up a test track with two tracks feed directly from the controller (track feed) separated with an isolated rail fed by the AR1. The same thing happened loco stalls on IRJ. Digitrax don,t want to know and have fobbed me off. 

Has anyone had any experience or has knowledge of the LDT kms-sg auto reverser?

[Porkster]

Sorry to bleet on about this problem but I just had a thought. Is there any possibility that it would have something to do with the loco's that I have. They are both new Hornby TTS Models.

One is a King Richard ll and the other a diesel electric 47033. 

Thanks for any thought, cheers

[Woody52]

Porkster, your sound locos should run smoothly over the join in the sections without the sound being interupted. Personaly I always like to use my least loved loco to do all my testing just in case the loco is damaged by the short, but I have never damaged one yet. I realise you only have sound locos.

Digitrax Manuals are very difficult to follow, just make sure you have done everything as directed in the manual.

If everything you have tried has failed, then maybe there is an incompatability between the components in your setup.

Peter

[Porkster]

I finally solved my RL problem. I purchased a PSX-AR which arrived this morning so I couldn't wait to install it, but guess what? Same problem! I checked with a voltmeter and concluded that the system was momentarily loosing power as the loco tripped the PSX unit. The PSX is fed by the track power upstream from the  PSX-1 circuit breaker so it took me a while to realise that it was the circuit breaker  tripping that was causing the probkem. The penny finally dropped when it dawned on me that it was a discrimination issue between the AR and the circuit breaker.

Sounds simple but it took all day to resolve. i then re-installed the original AR1 and it worked fine!! 

 

Thanks for all your help and guidance, regards Porkster