Perpetual motion?

[ptccox]

I have just installed a Digitrax DN135PS chip in an HO Bachmann DCC ready 2 truck Climax.  On the program track my NCE PowerCab recognised the manufacturer and the decoder.  I set the address number, but when I attempt to run the loco on the main it starts happily, but then will not stop!  Reducing the speed to zero on the controller has no effect whatsoever.  It will stop only if taken off the track.  If I then put it back on it stays still until I crank up the controller, when it sets off happily but, as before, refuses to stop when told to.  This happens in forward and reverse.

Any advice please?  I thought this would be a quick plug and play fun relaxation from the major scenic work I am doing at the moment!!   Is it the decoder?  Perpetual motion seems to defeat all logic, though of course the power is there with DCC, but why will it accept the command to start, but not that to stop?

Please put me out of my puzzlement.

Thanks, Peter

[rrinker]

 Try setting CV8=8 to reset the decoder. and see if it behaves the same way on address 3. If so, it could be a DOA decoder, or the loco is not really DCC ready - this shouldn;t keep it from stopping, but most Bachmann locos have capacitors and choke coils in the motor circuit which WILL interfere with smooth operations. It's generally enough to clip off the capacitors, the coils are in series and would have to be repalced with jumper wires to complete the circuit, but it's usually not necessary to remove them. The capcitors in question may be on the circuit board, or may be directly soldered on the motor terminals., it varies from model to model and even from production run to run of a given model.

 It sounds mostly like perhaps CV4 is a high value - deceleration momentum. Setting CV8=8 will reset all values to default in a Digitrax decoder, and you can work from there. Sometimes all CVs are not at factory default values fresh out of the package due to residual effects from testing at the factory.

                         --Randy

 

[ptccox]

Thanks very much for your prompt reply Randy.  After posting I went back and did a factory reset, and it clicked its way happily enough through all the CVs.  Back on the track the lights came on correctly for the direction set before moving off, but once set in motion it again refused to stop and the lights no longer worked.  I had already removed the capacitor closest to the decoder plug but left the other, as recommended at Tony's Trains website.  Can a decoder be faulty like this?  I am new to this, but imagined that DOA meant Dead, not b******* minded! 

Have you or anybody else had this sort of behaviour?

Thanks,  Peter  

[rrinker]

 When you say 'factory reset" and "clicked throught he CVs" in the same sentence I have to ask - did you just use the CV programmer menu and set CV8=8, or did you use the menu option on the Powercab that says decoder reset? Because the decoder reset menu item in the PowerCab actually sets specific CVs, which areonly guranteeed to apply to NCE decoders - some of the things are indeed generic NMRA DCC specified CVs, but it also sets some NCE specific ones, which are not necessarily the same function on another brand decoder.

 As for the way it's working, does it take off at full speed, or does it go at the speed you expect and then is just unstoppable? (Maybe we need to call Chris and Denzel - wonder if they'd be able to figure out a steam loco).

 Unfortunately, a decoder is a computer, so it can be 'dead' in many ways - it's possible also for the motor drivers to fail closed, so the loco with the 'dead' decoder would take off at full speed as soon as the wheels hit the rails. Can't say I've seen any personally, knocking on my very heavy wooden desk. I have yet to have a deocder fail or be dead out of the package.

                --Randy

 

[wjstix]

I would try the CV8=8 factory reset again, and maybe try running it on 03 before changing the ID number. I might try changing the decoder so it won't run on DC. I don't remember for sure what no. it is but I think it's one of the settings for CV29. You could also try clearing your DCC system out, just to be sure that no. you're assigning the decoder isn't already part of a consist that is still 'running'.

[ptccox]

Thanks again Randy and thanks Stix.  I used the NCE reset, so I will go off and try putting CV8=8.  I set it off at step10 and it moves off reasonably slowly, no jackrabbiting, but doesn't go any faster when I step up through 20, 30, 40, etc.  Once it has started it just keeps trucking along at the same slow pace.  I have made sure the decceleration is at 0 and switched DC off, I do not use consists, and I have checked that it isn't the NCE that is wrong, so if this reset doesn't work I suppose the next thing is to try another decoder: unfortunately I do not think I have one that fits in the small space.....  Oh, pish!

Anybody else had this trouble?  I am worried by the suggestion that not all Bachmann Plug and Plays are quite that simple and it might be the loco rather than the chip.

Thanks, Peter

[ptccox]

For those of you who find it so often frustrating that you do not know how things turned out in the end:- 

It is the decoder that is faulty.  Having tried all of the above, I fitted temporarily a DCC Concepts D2SAP decoder and it worked perfectly.  Sadly it is too big to fit in permanently, but the Digitrax one will be going back for replacement.....

Thanks for reading and thanks for your help,

Peter

[BroadwayLion]

Some older locomotives (and yous is not likely to be one of these) did not work well with new power supplies, exhibiting the same behaviors that you describe. This is because the power pack did not really shut everything off, but rather depended on the discharge of its capacitors to bring the track voltage to zero. Some locomotives it simply did not see and the power never went to zero.

Or something like that, anyway, what does a LION know, his fur stands on end when he walks across the carpet, but in any event I have experienced what you describe on a plain DC layout. On DCC all bets are off, since the power is always on. Still I do not see why a locomotive should not exhibit such behavior from internal current flows that are not expected by the DCC module.

ROAR

[hon30critter]

I don't know if it is only me but I have noticed on a few occasions that decoders don't respond to CV changes from my NCE Power Cab the first time. Sometimes I have had to re-input the change more than once to get the decoder to respond. Sometimes the change doesn't kick in until the power is cycled off and on. This has been most noticable with my Intermountain factory equipped sound locos.

Perhaps I am trying to work too quickly, but in all cases the CV changes eventually took.

FWIW

Dave