Loco not responding to commands

[dbduck]

2 weeks ago I was running on a club layout & one of my locomotives became unresponsive to commands. The layout is powered by an older digitrax DCS-100 I believe. The decoder in the loco I believe is a DH126p plug & play installed in an Athern loco

There were 5 locos running on the system at the time... 1) the loco in question..... 2) another of mine an Atlas with factory decoder    3&4) a pair of Geeps (make unknown-owned by another member)   4) a Big Boy (make unknown-owned by yet another member) with full sound operating. I also believe  some of the passenger cars in the Big Boy consist were lighted

There seemed to be no issues with any of the other locos responding.

An example of the issue: the loco would be running, but when throttle would be turned up or down or to "00" the loco would continue at current speed. I could take the loco off the track put it back on the track with throttle at "00" and it would sit still until it was throttled up...would respond for  maybe 2-3 mins then after that no response

I was using a tethered  DT400R plugged into a UP5 as the throttle for both of my locos. I swapped my locos on the throttle (L to R & R to L) with same results

I have run the loco on the the same layout twice (under same set up) since with no issues.

But no other locos other than mine were operating or on the tracks

I was not involved it the wiring of the layout.. but I do know that the cable connecting the DCS to the layout is a very small gauge (maybe 22/24awg) & is plugged into the layout  using a 1/4" phone jack..reminds me of a "guitar cord"  Nor do I know what size the Bus wires are feeding the tracks

 

Also I think I read somewhere that sound locos can "deprive other locos" from information?      Or can it be that the DCS, which I think is only rated at 5 (edited) amps, was at or near capacity?

[trevorsmith3489]

You might not have done anything.

But, with different members using different controllers on the same layout they may have done something to change your loco parameters - possibly putting it into a consist. It could be that one of the other locos had the same address as yours, a possibility if your loco subsequently works fine when no other locos are on the layout

Worth checking out with the other members.

[richg1998]

First thing I would do is a factory reset. I have run those decoders single with no issues though.

Rich

[dbduck]

text moved to original post 

 

[Stevert]

dbduck

I was not involved it the wiring of the layout.. but I do know that the cable connecting the DCS to the layout is a very small gauge (maybe 20awg) & is plugged into the layout  using a 1/4" phone jack..reminds me of a "guitar cord"  Nor do I know what size the Bus wires are feeding the tracks

That's a problem, and it could be what caused your control issue. If the layout is large enough to accommodate 5 locos (or more) at a time, it requires larger bus wiring to prevent voltage drop. The lighted passenger cars would only make this worse.

 

dbduck

Also I think I read somewhere that sound locos can "deprive other locos" from information?      Or can it be that the DCS, which I think is only rated at 3 amps, was at or near capacity?

Sound locos can obviously require more current, but they can't "deprive other locos from information".

Also, the DCS100 is a 5-amp booster, capable of powering way more than five locos (assuming HO-scale here, from your mention of a DH126). Since it wasn't tripping it's internal breaker, I doubt it was overloaded. Mine easily handles the 12-14 sound locos I have on my layout at any given time.

That brings us back to insufficient wiring.

[dbduck]

the layout is a semi permanant "module type" probably  100' x10' or longer so each main line prob is at least 225 + ft long  there is a  lift bridge that breaks up the bus 

one thing to note...even when the loco was in the section where the DCS was connected to the layout..there was no response

[dbduck]

I tend to agree with a wiring issue (wire size)...plus a 1/4" phone plug/jack connection has very little  connection surface between components ..esp at "the tip" 

not the ideal connection to conduct track voltage as well as digital information, plus the higher the amperage load (i.e.  more locos, lighted cars, sound, etc)  the more voltage drop is affected

[SPSOT fan]

Definitely sounds like some one dialed up the number of your loco. Did one of the other locos on the layout at the time have the same DCC address? Did they dial up your loco? That would be the most likely issue. In the future just “steal” the loco back. Communication between the other people running would be essential for preventing such a problem in the future.

[dbduck]

SPSOT fan

Definitely sounds like some one dialed up the number of your loco. Did one of the other locos on the layout at the time have the same DCC address? Did they dial up your loco? That would be the most likely issue. In the future just “steal” the loco back. Communication between the other people running would be essential for preventing such a problem in the future.

 

that was one thing we did check.. we even did a reset on the DCS to clear all info, then  called up each loco again making sure that there were no identical addresses. same result.... after  "listening" for a few mins.. the loco again quit responding

as I stated before you could take the loco off the track put it back on & it would "sit still"      if someone else's  throttle (or the command station) was telling it to go..it would have taken off

 i am leaning toward voltage drop, thus info drop,... since it's the voltage that "carries" the information down the bus and maybe that particular decoder is more (less?) sensitive to "weak" information

[gregc]

dbduck

after  "listening" for a few mins.. the loco again quit responding

are you saying it work ok and then stop?

 

dbduck

i am leaning toward voltage drop, thus info drop,... since it's the voltage that "carries" the information down the bus and maybe that particular decoder is more (less?) sensitive to "weak" information

if it's a voltage drop issue, the track voltage would be significantly different w/o anything on the layout and with multiple locos running and drawing power.

[dbduck]

Yes it responded to commands for a few mins but after that it would stay at what ever speed it was running at. Would not speed up slow down or stop

As far as voltage drop, it is directly affected by load.

if you ever use a voltage drop calculator, one of the parameters besides beginning voltage, length of circuit in feet & wire size is the amperage of the load

the greater the amperage the greater the voltage drop over the same distance 

 

[gregc]

have you confirmed that the voltage is lower than expected by measuring it?

it's odd that it only affect one loco

[dbduck]

I agree that affecting only one loco seems odd

as stated before the loco has since ran twice on the same layout even on the same track without issue

only thing that was different is the other locos & lighted passenger cars that were running at the time of issues were not present

Thats why I am thinking that the decoder in that loco is a little pickier when it comes to weaker data signals due to voltage drop 

 

 

[rrinker]

 Extra locos and lighted cars is a significant drop - especially if the cars are lighted with incandescent bulbs and not LEDs. ANd the bulbs can actually cause slight signal issues because of the coiled filaments acting like inductors. Normally not an issue, really, but with the also VERY inadequate wiring - 225' layout with smalelr than #22 wire and guitar plugs interconnectign them - you're lucky anythign runs. At the furthest end from where the command station is plugged n, I'm willing to bet you can drop a pair of pliers across the track and the system will not trip its breaker due to the huge voltage drop. Might actually end up melting some of that thin bus wire. That also means tehre's no protection if a loco derails and shorts the track.

 The RIGHT way to runa  power bus for a large mocular layout is to use #12 wire and ANderon PowerPole connections between the sections. Both are designed to easily handle the 5 amps of current with minimal voltage drop - but a single 225 foot run is really too far even with #12 wire. Even though the number of trains being used does not exceed the capacity of one booste, extra boosters are recommended to keep the length of run for each one to a minimum. 

 Maybe it works ok for now (except it doesn't, really, as your issue illustrates) but one of these days there will be serious problems because of the inadequate wiring, and most likely right in the middle of a public show, if you ever do show this layout off to the public. Our club layout had to be upgraded, in its original DC form, there was relatively thin wire used, but each module, or at most 2 or 3 modules, each had local power from DC walkaround throttles - power wasn;t really transmitted around the entire layout from one power point. When we went DCC, each module got a harness of #12 wire with the PowerPole connectors on each one, and the feeders were gradually changed over to connect to the approriate #12 bus wire - it's double tracked so each module has at least 2 sets of bus wires, modules with yards have 3 sets, plus there is anther bus to feed the stationary decoders for signals and switch motor controls, the track power boosters do not feed this stuff. ANd a fixed DC voltage pair for structure lighting. All color coded, and matched across the PwoerPole conenctors so when joinign modules you just plug the two connectors into one another so that the same color wire is across on both sides.

                                    --Randy

 

[dbduck]

The layout was built probably 20 or so years ago as a portable modular display layout and was originally DC. It is now permanently set up at a local toy mall

i dont think the bus wires are 20-22 gauge just the ”guitar cable” connecting the DCS to the layout

The wiring that is visible under the lift bridge looks to be 18 gauge, so assuming the size of the buses as well

I think the jumpers between modules are actually hard wired from terminal strip to terminal strip.

As I said I was not a part of the original wiring and totally understand the need for larger bus wires but really can only suggest an upgrade since I am a guest operator

The 1/4”  jacks were initially  installed so the original DC power packs could be plugged into the layout, now being the way to hook up DCC as well.  That being said, those jacks seem to be the original ones, so they are probably 20 years old & worn out 

 

[AlienKing]

I've had issues with DH126p decoders in a few locomotives.  The engines would respond OK for a bit, but become unresponsive unless you physically pushed or pulled them. 

The first thing I did was verify that I had DC dual mode turned off (it was).  Next I cleaned the track, checked the connections, etc but that was alight as well. 

The problem for me turned out to be the capicator accross the motor leads.  I ended up desoldering the caps from the light board and the problem went away completely. 

[wjstix]

trevorsmith3489

You might not have done anything.

But, with different members using different controllers on the same layout they may have done something to change your loco parameters - possibly putting it into a consist. It could be that one of the other locos had the same address as yours, a possibility if your loco subsequently works fine when no other locos are on the layout

Worth checking out with the other members.

 

To me this seems the most likely problem. I've done it myself on my home layout - dialed up an engine, was able to get it to run, but it wouldn't quite stop. Eventually determined it had been in the trailing (non-lead) engine in a consist that hadn't been deleted. Once I ended the consist, the engine worked fine. My guess is someone had set up a consist with an engine with the same no. as yours and that was affecting your engine.

[SPSOT fan]

I reread the OPs first post and it sounds to me like your throttle was failing to send messeges to your loco, so the loco continue to follow the last command you gave it that it received.