DCC shorts and TTS loco's running wild

[AddlestoneP]

Hello everyone,

We have something strange going on.

If we have a short during normal running, perhaps caused by a derailment, our TTS loco's go mad. What I mean by this is that set off in the direction they were last given, at full speed and are not controllable even if the short is cleared. 

We transferred them to the test layout and caused short to occur and off they went. As we have quite a few I cannot simply grab them. All I can do is pull the power and reset everything. With RM, this is not ideal and with a PC reboot as well, we are down for ten minutes or so.

Also, this has meant collisions and damage.

Does anyone know why this happens and does anyone know how to solve it? Only our Hornby TTS are affected, everything else is fine.

Thanks,

Howard

Addlestone Parkway - A OO Gauge Garden Railway www.addlestoneparkway.co.uk

[2e0dtoeric]

First guess - disable dc running!

I don't recall which code it is to do that, and I belive it can vary between different decoder manufacturers, anyway, but it will be in the manuals.

[poliss]

Mark Gurries explains what causes runaways here.

https://sites.google.com/site/markgurries/home/dcc-problems/decoder-problems/decoder-loss-of-control

 

It's all done in CV29 2e0. It's an NMRA standard and is the same accross all NMRA decoders.

To turn DC running off you enter 2 into CV29 or 34 if you're using long addresses. It's all shown in the DCC CV29 calculator.

http://www.2mm.org.uk/articles/cv29%20calculator.htm

 

You should also be able to do it in Railmaster without touching the actual CVs themselves I think.

[Nick_]

 Using RailMaster it is very easy to change the CV settings. (Use the i button in the locomotive dialog). I think it is pretty universally suggested that If you do not intend to use your locos on a DC layout the disabling DC Operation in CV29 is a sensible step even if it does not turn out to then fix the highlighted problem.

[2e0dtoeric]

Thanks, Poliss.

😛

[Fishmanoz]

To be more precise, to disable DC Running in bit 2 of CV29, subtract 4 from whatever the value of the CV is now.

[AddlestoneP]

Thanks all I will do this tomorrow.

Howard

[poliss]

Not only does disabling DC prevent runaways, it also speeds up the response time of your loco, because the decoder doesn't have to check that it's on DC power all the time.

[96RAF]

Resetting RM should just be matter of clicking the little red square in the big red stop button on screen. No need for a restart and certainly you should not have to reboot your pc.

if you search on the RM  forum you will even find a picture of this button amongst all the discussion there has been previously about shorts in RM - well worth finding and digesting.

[RB51]

I didn't know that Poliss. I might turn mine off in that case. R-

[81F]

 As mentioned before I too have runaways, most were sorted by switching to DCC only on the problematic locos. but having hatd wired a decoder the other day I was programming the loco when my GWR City of Brmingham went off like a rocket. No reason, no cross over from the programming track. Odly it didn't do it again when I reprogrammed the original loco.

 

he only common theme there seems to be is that they were generally Bachmnn 1 pin decoders. I wonder what processor they use?

[AddlestoneP]

Resetting RM should just be matter of clicking the little red square in the big red stop button on screen. No need for a restart and certainly you should not have to reboot your pc.

if you search on the RM  forum you will even find a picture of this button amongst all the discussion there has been previously about shorts in RM - well worth finding and digesting.

Hi, Thanks for your help with mt TTS problem. I wish RM was that easy. I do that every time and still end up restarting RM. The product has been great for us but stability has avoided us somewhat. Mark at Hornby has been great I must add. We run 50 plus trains (8 at any one time) and signalling is being installed over our 800 metres of track. ARAM continually disconnects (I have checked the COM number) and it is 95% of our frustration right now. We are at the point where we will bin it and go with Lenz or other who have current detection. It will be expensive but it will work every time and RM will be used for fleet decoder management. 

Any help to stabilise RM most welcome.

Thanks,

AP

[Fishmanoz]

Your RM should be stable, experience here tells us if it's not, then your setup may not be quite right.

 

All the setup instructions can be found in the 2nd top locked thread in the RM forum, thread titled Setting Up and Getting Started.  Look at all of it, but look particularly at the bottom post from HRMS on the correct lines in your ini file.

 

Check that out and report back.  If you think you have everything correct there, you might email HRMS from the facility in the Help window of RM and see what they think.

 

PS.  This is quite separate to turning off DC running in CV29 to stop the runaways.

[RDS]

... our 800 metres of track ...

 

Wow, that must be some layout!  Any chance of a picture?

 

[Chrissaf]

http://addlestoneparkway.co.uk/

[Fishmanoz]

Now there's a layout that's going to be needing a booster or several.  That won't be the stability issue though.

[87A driver]

Hi, Just joined this tts forum as i have bought 4 tts locos recently, and all seem to be suffering the same fault as everybody else seems to be having! - Out of the box after being set up on a spotless clean, solder connected programming track, they all exibited the same faults!  Creeping forward with the controller -OFF- , and, taking off at full speed for no apparent reason!!

Having looked on several different forums, it seems i'm not alone!

What seems to have cured 3 of them, a Duke, C of North, and one King, is by setting the Back EMF CV to =0.

This is something that I as a customer shold not have to do on a new product , out of the box!

I have them all set not to run on DC,  but the fourth loco,(another King), although set not to run on DC, at least twice!, Will still run forward on DC, and intermittently lurch backwards on DC.

Now like many of you out there, the control sysstem makes no difference whatso ever, (i am using on my own layout a Fleischmann multimous, but have tried all these on Hornby's dcc, and others layouts, with differing dcc units), and as Hornby's stuff is now Supposed to be NMRA compliant, there should be no difference across the manufacter's products!

This seems to be another case of us Brits putting up with faults that the restof the world wouldnt, again!, as the volume of complaints about this issue on several blogs, must be a large percentage of the sales of these loco's!.

[87A driver]

Hi, I forgot to add that, as someone else mentioned, DO NOT use DC track power connecting clips to feed power to your programing track as they do indeed have a suppresor in them, that stop you being able to program properly!

Also i have being able to stop  the 4th tts loco creeping forward by altering CV 5 to - 66 from 63. as this seems to be the value that it needs to syncronize with the central position on the controller knob.(there is no cv5 in the Hornby paperwork, but several other 'blogers' on various web sites found this out

I'm still not very impressed with these tts locos as being 'good value for money', as most users seem to be having problems with them.

Hornby are starting to make some beautiful new models, you only have to look at the B12 coming out, but seems a shame to let buyers down with cheap motors and chips.