I think I just fried a DCC loco chip - diagnosis assistance needed

[Andrew F]

With a motor wire removed and another chipped loco on the programming track alongside, both chips should reset.

[Phil S]

What does the 'emergency stop' or 'stop' button on your controller do? - Does it remove track power or command all locos to zero speed ?

(Again - a multimeter would verify this) [ On my controllers this is a user option - or it may stop ONLY the controlled loco ]

 

I saw no response to someones suggestion that you set the speed to Zero for that loco number, BEFORE placing the loco back onto the track.

What happened - did it still 'run away?

 

In the absence of a rolling road -

Turn the loco upside down and connect the 'track power' via 2 UNDRIVEN wheels that have current collectors using either some cheap croc clip leads, or holding the bared ends of 2 wires from the controller.

[Pete the Elaner]

What does the 'emergency stop' or 'stop' button on your controller do? - Does it remove track power or command all locos to zero speed ?

(Again - a multimeter would verify this) [ On my controllers this is a user option - or it may stop ONLY the controlled loco ]

 

I saw no response to someones suggestion that you set the speed to Zero for that loco number, BEFORE placing the loco back onto the track.

What happened - did it still 'run away?

PowerCab only stops the loco under control.

PowerPro cuts power to the entire layout with a double press. This is a feature not included in PowerCab though.

 

The second suggestion will not work. Setting speed to zero will send a real-time command to the loco in question. It will not keep transmitting this until it receives an acknowlegdement. If the loco is not on the track at the time, it will not receive the command.

[dhjgreen]

Some decoders need a load like the motor to accept programming so disconnecting the motor may not guarantee being able to reset the decoder but worth a try.

Rob

Is it possible to disengage the motor from the gears?

[imt]

Is it possible to disengage the motor from the gears?

 

I dare say it is but I'd rather like to do this without completely dismantling the chassis.  IF that's the only way to reset this chip I think I don't want it!

[Ray H]

Can you place something big, bulky and insulated at each end of the track and place the loco on the track at the end nearest to that which you expect it to run towards? Hopefully that will be enough to stop the loco taking a liking to any non-track area and allow you to switch the PowerCab into programming mode or at least choose the first option if you can set the PowerCab into its programming track mode before you place the loco on the track.

[imt]

Well thank you for all your attempts to help me.  This is what I have tried:

 

1) un-solder grey wire from Class 37 motor, put Zen chip in socket of Class 37, put PowerCab into PCP socket, set Program Track, try to reprogram but cannot read CVs

2) place Class 55 with chip on program track as well as Class 37 as an attempt to provide "ballast" for the process, repeat 1 above, still couldnt read CVs on 37 but could on 55, managed to cause short address of 37 to go to 3, but setting CV 8 to 8 seemed not to do anything.

3) re-soldered grey wire, moved Class 55 (Hatton) chip to Class 37 chassis checked that DCC control and reprogramming worked OK on that chip on the 37 chassis.

4) removed Hatton chip and inserted Zen chip, put heavy weight on wooden box at end of track, connected Power Cab, 37 chassis with Zen chip, chassis pushed wildly against box, tried setting "program track mode" it reported "short circuit present" so ceased the experiment.

 

It seems to me that there is a short within the Zen chip - since the Hattons one works properly - and that it is therefore unusable.  I am not doing anything more.  Either DCC-C accept that there is a problem and hopefully replace the chip or I am £17 out of pocket and I'll buy a chip that works.

 

I am in contact with DCC Concepts and will pass the current progress to them.

[Butler Henderson]

Its well worth investing in one of these

 

http://www.esu.eu/en/products/decoder-tester/

[imt]

Its well worth investing in one of these

 

http://www.esu.eu/en/products/decoder-tester/

 

Thank you. Yes I do know about it and mentioned the decoder tester in earlier posts.  It's really a case of I have never had any trouble before nor do I expect any more. I have 36 DCC loco's (many with sound) with no problems and this particular Zen chip has misbehaved/been fried and I think I shall just cut my losses.  Either the manufacturer will replace it or not, but the decoder-tester costs the equivalent of 2 new chips with stay alive and so I would think it not likely to offer me much return for the money. 

[Butler Henderson]

You could screw a lump of wood across the end of the programming track to stop the loco whizzing off somewhere whilst you try reprogramming the decoder.

[Nigelcliffe]

Sure is a problem of understanding - mainly mine but I am trying to catch up.  I put the PowerCab into "set program track mode" and my trusty multimeter assures me that there is 13.5 volts AC there.  It's only a cheap Maplin one so it probably isn't very accurate, but there is AC power there. "Normally" behaving locos of course just sit there - the duff Zen chip likes the power and goes wild.  Sorry but you are possibly in error or my PowerCab doesn't work properly.  It is possible but it seems to do everything else right?

 

Anyway I think I have proved the chip is duff - see posts 13 and 17 above. Happy for any other comments from you - I NEED to learn these things.

 

Ignoring the duff chip (which seems to be answered in the rest of the thread).

 

For a proper programming track, which is suitable for testing installations prior to running, there should be no volts on the track when you place the loco on the track.  There should only be tiny bursts of power whilst a programming read or write happens, these are a fraction of a second long.  Those bursts are of limited power, and a decoder will withstand those even with a dead-short over the outputs.    

So, either find when in the sequence of button presses that the PowerCab goes to no-volts, then put loco on track,  or, invest in the NCE Auto-Switch device (which I'd recommend to any PowerCab owner to deal with this issue).

[imt]

Ignoring the duff chip (which seems to be answered in the rest of the thread).

 

For a proper programming track, which is suitable for testing installations prior to running, there should be no volts on the track when you place the loco on the track.  There should only be tiny bursts of power whilst a programming read or write happens, these are a fraction of a second long.  Those bursts are of limited power, and a decoder will withstand those even with a dead-short over the outputs.    

So, either find when in the sequence of button presses that the PowerCab goes to no-volts, then put loco on track,  or, invest in the NCE Auto-Switch device (which I'd recommend to any PowerCab owner to deal with this issue).

 

The NCE web pages say as follows:

 

If you want a dedicated programming track to use with you Powercab we have the AutoSW for that purpose.

The AutoSW is a smart relay board with one input (two wires from powercab output) and two outputs. One output for the main layout and a second output for a programming track. 

The Auto_ SW senses when you put the PC into program track mode and energizes a relay that disconnects layout track power and connects a dedicated program track.  

The auto sw  is designed to detect packets on the DCC track bus that initialize service mode programming aka- programming track mode. When it sees those packets it throws a relay disabling one set of outputs and activating the other.

 

How does that do what you say it should, i.e. provide no power to the program track?

 

I have a further problem in that this seems to assume that the program track is an integral part of the whole layout and that you wish in some way to isolate it when you want to do programming.  If that's right - then since I have a completely separate piece of rail how does the switch help me?  Currently I have a separate PCP which is wired to a separate piece of rail, so I don't need to isolate it from the layout (presumable so I don't accidentally reprogram some other loco) since it stands by itself anyway.

 

I am sure that it would be really helpful if I could get my simple mind round this!

[HLT 0109]

IMT

 

It seems to me that the simplest solution is to send the decoder to DCC Concepts (you say you are in touch with them) asking them to diagnose the problem.  If the decoder only requires a rest, they will surely do it for you - if the decoder is defective they will no doubt replace it (unless they can show you have damaged it).  Alternatively, if you have a good model shop nearby, they might be able to reset the decoder for you, thereby avoiding popstage costs and delay.

 

Harold.

[HLT 0109]

I have a separate PCP in a box to feed it, the NCE PowerCab is physically disconnected from the layout and connected to this entirely separate track.  Other locos perform properly (i.e. sit there and do nowt until given a command).  This loco when put on the powered programming track - but without the NCE POwerCab having its loco number set or any accelleration set - goes wild.

 

Are you sure there isn't a problem with the connections to/from the PCP feediing the programming track - something in the wrong socket?  It seems very odd that that piece of track is getting 13.5v.  You say other locos perform normally - do you mean when they are on the programming track - because they shouldn't perform at all.

 

My programming track is phyisically connected to my layout but isolated from it by insulted rail joiners and has a separate power supply feeding it.  If you have only one power supply feeding both tracks (albeit through separate PCPs), perhaps that is why the programming track is showing 13.5v - mine shows Zero when switched on.  Or do you phyisically unplug the supply from the layout PCP and plug it into the Programming track PCP?

[imt]

  Or do you phyisically unplug the supply from the layout PCP and plug it into the Programming track PCP?

 

Yes. Sorry if "I have a separate PCP in a box to feed it, the NCE PowerCab is physically disconnected from the layout and connected to this entirely separate track." wasn't clear.  Obviously the way you do it and the way I do it is completely different, and from what you are saying you get what Nigel expects.  I am going to try to see if I can set things up so that I get what Nigel says I should get - but I don't see how at the moment.

 

IMT

 

It seems to me that the simplest solution is to send the decoder to DCC Concepts (you say you are in touch with them) asking them to diagnose the problem.  

 

Indeed Harold.  I hope that that is what they will offer to do.  But they haven't yet.  I cannot just send them the chip unless they agree to accept it.

Edited September 9, 2017 by imt

[imt]

You could screw a lump of wood across the end of the programming track to stop the loco whizzing off somewhere whilst you try reprogramming the decoder.

 

Well I did the next best thing - see post #32 point 4.  The wooden box actually holds my spare lumps of lead and steel.  I backed off when the PowerCab said "short circuit detected" because I don't want to damage anything (well more than it is already).  As Harold says, it would be best if DCC-C will take the chip in for testing.  They will have better equipment than me and would be able to say quite quickly what was the matter and how it was caused (perhaps).

[trustytrev]

Hello,

        MERG do a decoder tester in the pocket money range which would enable you to test the decoder out of the locomotive and enable you to reset it.

Only £1.38 but you have to be a member, However that can be worthwhile just to access other things that could be of interest and the vast amount of useful  information relating to model railways

trustytrev.

[Phil S]

Hello,

MERG do a decoder tester in the pocket money range which would enable you to test the decoder out of the locomotive and enable you to reset it.

Only £1.38 but you have to be a member, However that can be worthwhile just to access other things that could be of interest and the vast amount of useful information relating to model railways

trustytrev.

Phil: a simple tester, which will work with all decoders, is a 9V battery held across a set of wheels ( assuming sufficient pickups ) or held across a short piece of totally isolated track with the loco placed on it..... Useful for testing both analogue and DCC fitted locos, regardless of programmed address, as long as DC running is enabled. As mentioned before ... Testing the loco upside down is a simple way of preventing physical runaway.

 

Most motor power output stages are formed by an H-bridge of 4 'transistors'.. Which MAY be in a single package. If one has blown there is usually a small visible hole in the surface...or even a cone shaped hole.... At worst a totally missing device! ....caused by the excessive heat build up during the short circuit or other fault. Because they are normally driven in 'diagonal-pairs'. ...i.e. top left (via motor as horizontal bar) to bottom right for one direction, and top right to bottom left for the other..... One direction may work normally, but the other direction has a shorter path straight down...missing the motor. Alternatively, one of the transistors maybe turned on permanently.... Giving normal performance in one direction, but maximum speed in the other.. Which appears to be the most likely scenario here.

[Andrew F]

I just remembered that not all DCC concepts decoders reset with CV8. I think it may have been CV10 to the value of 8 but probably they were the older decoders.

[imt]

I just remembered that not all DCC concepts decoders reset with CV8. I think it may have been CV10 to the value of 8 but probably they were the older decoders.

 

DCC Concepts have just got in touch - my original emails seem to have gone walkabout so I have provided a copy.  Hopefully I'll get some input from them later on.  The other suggestions (for me) are moving off into the realm of fantasy.  I'm not much of an electronic whizz, and certainly don't wish to get involved in building breadboard circuits.  On the other hand there will be other readers to whom the information may be helpful so I am not suggesting that they stop - its just that I won't be joining in.

 

I am about to do some experiments on finding how I get my separate piece of track to operate as a programming track like the above posts have suggested it should - i.e. with no AC to the rails except when commands are issued.

 

I should point out that ideas of using DC in my case have already been dealt with - I put a blanking chip in and ran the chassis under DC to prove 1) that the conversion was indeed OK and 2) that the chassis still worked and has no faults.  I had also programmed the Zen chip to get the speed/accelleration right and switched OFF DC working. The chassis in question now has a Hattons 8 pin direct chip in it and the Class 37 body properly fitted and is working OK.  It ran six 6 coach trains in my timetable last night.  The 55 which should have been doing the work sat forlornly on one side with no chip!  The Zen with the stay alive had a much better working performance in the Class 37 than the Hattons does - and I have tentatively ordered another Zen 360 direct but I will not fit it until I get some reassurances from DCC-C that the chip will indeed handle an old Lima pancake.

[Crosland]

Some decoders need a load like the motor to accept programming so disconnecting the motor may not guarantee being able to reset the decoder but worth a try.

Rob

It's the system that needs the motor connection to provide a current pulse that can be detected when programming the decoder on the programming track.

 

Decoders will happily accept writes with nothing connected, but you cannot read anything back, and the system may say there was an error.

Edited September 10, 2017 by Crosland

[smokebox]

Quote.

"I put a blanking chip in and ran the chassis under DC to prove 1) that the conversion was indeed OK and 2) that the chassis still worked and has no faults."

 

That doesn't prove that the chassis has no faults.  It only proves the the loco will run on dc with a blanking plug fitted.

 

Slightly different circuitry is brought into operation when a DCC decoder is plugged in, so a loco that works perfectly with a blanking plug in can destroy a DCC decoder when that's plugged in.

 

A tiny whisker of solder on the DCC socket between two adjacent pins or if a wire is misplaced during manufacture is all it takes and factory misplaced wires are all too common.

[Torper]

Are you sure there isn't a problem with the connections to/from the PCP feediing the programming track - something in the wrong socket?  It seems very odd that that piece of track is getting 13.5v.  You say other locos perform normally - do you mean when they are on the programming track - because they shouldn't perform at all

 

I'm getting confused about this too.  I have an NCE PowerCab and a separate programming track with a different power supply to the main layout.  Are you saying that when the PowerCab is connected in the normal way to the Programming Track via its own PCP and switched to "Use Programming Track", there should then be no or little voltage detected in the rails?  Certainly that doesn't happen in my case - I still get the full 13.5 volts in the rails.  Or does it only happen if you get the Auto Switch device?

 

Looking simplistically at the OP's problem, it seems to me that as the 37 chassis performed properly when the Zen chip was removed and replaced by a Hattons one, but the problem then recurred when the Zen chip was put back in (post 32 above), the obvious answer is that the Zen chip is defective.

 

DT.

Edited September 10, 2017 by Torper

[imt]

Quote.

"I put a blanking chip in and ran the chassis under DC to prove 1) that the conversion was indeed OK and 2) that the chassis still worked and has no faults."

 

That doesn't prove that the chassis has no faults.  It only proves the the loco will run on dc with a blanking plug fitted.

 

Slightly different circuitry is brought into operation when a DCC decoder is plugged in, so a loco that works perfectly with a blanking plug in can destroy a DCC decoder when that's plugged in.

 

A tiny whisker of solder on the DCC socket between two adjacent pins or if a wire is misplaced during manufacture is all it takes and factory misplaced wires are all too common.

 

Thank you for that warning.  However in the present case I have also run it with a chip in the plug and it works.  So that isn't the cause of my particular problems - though I will keep the warning in mind for other occasions.

[imt]

I'm getting confused about this too.  I have an NCE PowerCab and a separate programming track with a different power supply to the main layout.  Are you saying that when the PowerCab is connected in the normal way to the Programming Track via its own PCP and switched to "Use Programming Track", there should then be no or little voltage detected in the rails?  Certainly that doesn't happen in my case - I still get the full 13.5 volts in the rails.  Or does it only happen if you get the Auto Switch device?

 

Looking simplistically at the OP's problem, it seems to me that as the 37 chassis performed properly when the Zen chip was removed and replaced by a Hattons one, but the problem then recurred when the Zen chip was put back in (post 32 above), the obvious answer is that the Zen chip is defective.

 

DT.

 

Join the club!  I have just tried experimenting with my NCE PowerCab on my separate PCP and I can find now way to make the voltage disappear, nor does It do so before or after any valid command I can give it.  Maybe the special extra switch board actually does this?  I don't know, and I don't really see the need in regular use.  It MIGHT have helped in this case - I just don't know.

 

I'm a simple man too. As you say, since the chassis works fine with another chip in it there must be a fault in the Zen one - but did I cause it, and if so how?  I do want to continue with using Zen chips with their stay alive, I don't want to keep blowing them if that's what I did.  Hopefully DCC Concepts will agree to examine the chip - they haven't yet.