NCE Powercab - Sprog control puzzle

[highpeakman]

I use a NCE Powercab on my layout. I also use Decoder Pro with a Sprog II v3 for testing/configuring locos on test rollers on my workbench. I have happily used this combination for some years without any problems. Decoder Pro (running on Windows 10) and the Sprog are up to date on firmware/software. The Power Cab uses v1.65 firmware.

 

One of my locos - a Bachmann Ivatt 4MT 2-6-0 (32-580) has previously been used successfully, without problems, when used on the layout. It is fitted with a Digitrax DZ125 decoder.  

 

After some months of not being used I put the loco back on the layout and found running problems - jerky movements and poor speed control. I removed the body and carefully lubricated the loco and ran it for some time on my roller test bed controlled by the Sprog. Back on the layout and it still ran badly but also exhibited strange behaviour - principally it would run away even when the throttle was turned off. I then put it back on the Sprog test bench and reset the decoder. Checked the programming and everything was back to factory settings. I then reprogrammed the addresses and speed settings. Back on the layout with the Powercab and it still exhibited poor running as before - still running away. So this time I reset the decoder again using the "programme" track and Powercab. Still no improvement.

 

Back to the Test bench and Sprog - another reset - loco runs well on rollers. Back to the layout and Powercab and now it won't run at all!

 

Back to test bench - runs fine - won't work (dead) on Powercab layout. Everything turned on/off multiple times - ALL other locos on layout work as normal with both Powercab and Sprog.

 

It's puzzling me - any ideas please?

 

(Likely action will be to replace the Digitrax with Zimo as I have had a couple of problems with Digitrax before unfortunately).

Edited November 7, 2019 by highpeakman
correction

[Crosland]

First thought, it is something to do with the chassis/pickups. The wheels are supported differently on the rollers, compared to running on the track, and making better contact.

 

Second thought, is this your only DZ125? Can you try it in a different loco?

[highpeakman]

39 minutes ago, Crosland said:

First thought, it is something to do with the chassis/pickups. The wheels are supported differently on the rollers, compared to running on the track, and making better contact.

 

Second thought, is this your only DZ125? Can you try it in a different loco?

 

Thanks for the suggestion. The rollers on my test bench are mounted on a short piece of track and it runs along that OK as well as the rollers. So I don't think it is a wheel/contact problem. Plus, initially at least, it did work on the layout.

 

I had already thought about fitting the DZ125 to a different loco but it is just a matter of time to sort out another loco and fit the chip in that. Most of the locos with other DZ125s in are hard wired so a bit of a faff as this one uses the 8 pinplug. I also can't remember which other locos have 8 pin plug in decoders even if of a different type so would probably have to remove some bodies to see what is fitted. Haven't done it yet and I guess I hoped that someone may have another solution before I took that course of action.

 

Thanks for responding. I appreciate all suggestions.

Edited November 7, 2019 by highpeakman

[Nigelcliffe]

3 hours ago, highpeakman said:

 I then ………. reset the decoder. Checked the programming and everything was back to factory settings.

 

Did you check this, or just assume ?    ie. did you READ every CV back in the decoder into DecoderPro and check it, or just make the assumption that all the CV's were reset ?

 

Anything other than reading back every CV is "assumed it was reset"  to a greater or lesser extent.    I'll normally assume a decoder resets when I tell it to do so, but things partially resetting for weird reasons isn't an un-reported phenomenon.   Odd decoder behaviour can be down to settings in obscure CVs. 

 

And, I assume you're clear on the differences between "short" and "long" addresses, particularly on the PowerCab where a short address of, say 49, is different to a long address of 0049.  Both can be controlled independently.

 

 

- Nigel

 

 

[highpeakman]

2 hours ago, Nigelcliffe said:

 

Did you check this, or just assume ?    ie. did you READ every CV back in the decoder into DecoderPro and check it, or just make the assumption that all the CV's were reset ?

 

Anything other than reading back every CV is "assumed it was reset"  to a greater or lesser extent.    I'll normally assume a decoder resets when I tell it to do so, but things partially resetting for weird reasons isn't an un-reported phenomenon.   Odd decoder behaviour can be down to settings in obscure CVs. 

 

And, I assume you're clear on the differences between "short" and "long" addresses, particularly on the PowerCab where a short address of, say 49, is different to a long address of 0049.  Both can be controlled independently.

 

 

- Nigel

 

 

 

Didn't assume. As I mentioned above I did check some of the CVs. Addresses and speed settings and a few other things were all reset every time I did it. I admit that I did not check every single one though.

I also reset using Sprog and separately using the Power cab and CV8.

 

Originally this model used short addresses but I did alter it to use the same long address but have now altered it back.

 

However you are spot on it seems - I went to the Powercab and entered 0019 and it runs correctly! I didn't realise the difference.

 

That is obviously where the problem lies. Thank you very much indeed for solving that one. It was driving me mad!

 

Much appreciated.

[highpeakman]

Loco now working on both layout and Test rig Thanks to Nigel however there is still a problem with the decoder in that loco still runs away on zero throttle.

 

Zimo replacement has been ordered.

[Ray H]

Have you tried increasing the start voltage CV2 to see if that makes a difference? Just a thought.

 

You could also try altering CV3, the acceleration rate. Again, it's just a thought.

[highpeakman]

Speed settings (including acceleration, etc) have been altered but haven't changed behaviour.

The loco starts and accelerates normally but then does not slow down when you turn down the power.

As mentioned above, it has been factory reset by two different methods and then CVs changed but still behaves erratically.

I have experienced such problems before with Digitrax decoders although I am not saying they are poor. I have some that are behaving perfectly but I will replace this one with Zimo and see what happens.

[Ray H]

Check CV4. That might be very high and could account for the apparent failure to slow down when the throttle is reduced to zero.

[highpeakman]

New Zimo fitted. Smooth correct running now.

 

CV settings identical to Digitrax so I think there was some form of problem with it.

 

Thanks to everyone for suggestions and help.