First dcc converted loco start stop

Post all your DCC only problems, solutions and discoverys here.
Stano100
Posts: 13
Joined: Sun Nov 11, 2018 9:41 am

First dcc converted loco start stop

Postby Stano100 » Thu Dec 27, 2018 4:13 pm

Hi all

I have just had my first attempt at converting a dc loco to dcc. I have fitted an 8 pin decoder to a old Hornby 125
The loco ran well in dc mode. As a beginner I have got a decoder for Hattons, think there own brand.

I have a Roco Z21 controller ( I like being able to use the iPad)

When I run the loco I converted it runs for a short distance then stops the starts again before stopping again. (This continues). Using the controller I can change the change the direction, and it only runs when there’re is power sent to decoder. Don’t think decoder is overheating as it does not feel warm.

The loco seems to be stopping mainly near points.

I have locos that are factory fitted dcc and they run round same track without any problem.

GWR_fan
Posts: 4794
Joined: Sun Apr 29, 2012 11:57 pm
Location: Antipodes

Re: First dcc converted loco start stop

Postby GWR_fan » Thu Dec 27, 2018 4:55 pm

Most likely loss of power pickup as the pickups on early Hornby locomotives were limited (I assume a ringfield conversion). Without a stay alive any loss of power will cause the loco to reset.

Stano100
Posts: 13
Joined: Sun Nov 11, 2018 9:41 am

Re: First dcc converted loco start stop

Postby Stano100 » Thu Dec 27, 2018 5:18 pm

Sorry yes a ring field motor

What is a stay alive?
Thanks

User avatar
Bufferstop
Posts: 11340
Joined: Thu Mar 11, 2010 12:06 pm
Location: Bottom end of N. Warks line

Re: First dcc converted loco start stop

Postby Bufferstop » Thu Dec 27, 2018 5:21 pm

The old HST used the wheels- bearings- chassis block of the two bogies to provide power to the ringfield motor. I always found the pickup from the front (unpowered) bogie to be a source of trouble, mainly due to the stiffness of the connecting wire and the weak grip of the connector tag onto the diecast block. If you have, or can improvise a cradle tip it upside down connect each rail to one of the bogies using crock clips, get the motor running and the wobble the bogies around to simulate the movement of the bogies in the body. If you get any cutting out the source of your trouble is the quality of the Hornby wiring. A momentary disconnect whilst running on DC will go unnoticed especially with the ringfield motor which has a slight flywheel effect, on DCC it causes a reset, which you are sure to notice.
Growing old, can't avoid it. Growing up, forget it!
My Layout, My Workbench Blog and My Opinions

GWR_fan
Posts: 4794
Joined: Sun Apr 29, 2012 11:57 pm
Location: Antipodes

Re: First dcc converted loco start stop

Postby GWR_fan » Thu Dec 27, 2018 9:25 pm

Stano100 wrote:...............What is a stay alive?
Thanks


A stay alive is commonly used on decoder equipped locomotives where stalling is common, usually with a short wheelbase steam loco or diesel. It is basically a capacitor with a diode and resistor in the circuit and is connected to the decoder "+" and decoder "-" terminals on the chip. Some decoders come pre-fitted with stay alive terminals. The stay alive acts like a backup power source when the main power pickup momentarily fails. It is though not an option or band aid solution for poor power pickup as the capacitor must be charged up from the decoder. Only downside is that with a stay alive the analogue (DC) function on the decoder must be disabled using CV29.

Stano100
Posts: 13
Joined: Sun Nov 11, 2018 9:41 am

Re: First dcc converted loco start stop

Postby Stano100 » Thu Dec 27, 2018 11:18 pm

Hi

Thanks for responses I think I will look for a decoder with stay alive then

The dcc fiactory fitted engines are running ok so I do not think it is dirty track or wheels

User avatar
Roger (RJ)
Posts: 1379
Joined: Tue May 29, 2007 2:59 pm
Location: Nottingham, UK.

Re: First dcc converted loco start stop

Postby Roger (RJ) » Thu Dec 27, 2018 11:25 pm

It could possibly be that the motor is taking more current than the decoder is able to supply, causing it to shut down to prevent it being damaged. Another possible cause is dirty wheels preventing good current flow from the rails. Some models are more affected by dirty track and wheels than other models, especially if there are fewer pickups.

GWR_fan
Posts: 4794
Joined: Sun Apr 29, 2012 11:57 pm
Location: Antipodes

Re: First dcc converted loco start stop

Postby GWR_fan » Fri Dec 28, 2018 5:18 am

Stano100 wrote:Hi

Thanks for responses I think I will look for a decoder with stay alive then...............................


Assuming as stated in a previous posting that the decoder is not being overpowered with a high amp draw you can fit the bogie power pickups from a later Chinese ringfield locomotive. This will give you four power pickups on the leading bogie and not the standard two, plus a better more reliable method of wire attachment.

User avatar
RAF96
Posts: 557
Joined: Tue Feb 19, 2008 1:39 pm
Location: Dereham, Norfolk, UK

Re: First dcc converted loco start stop

Postby RAF96 » Fri Dec 28, 2018 11:37 am

I always improve the pickups on these old models where the front bogie provides one rail pickup and the motor bogie provides the opposing rail pickup.

Look for the service sheet for a slightly more modern version of the ringfield motored loco and use the improved pickups from there. Usually the front bogie picks up via the axle, whereas you can fit a ‘bridge’ pickup that collects from both sets of front wheels.

Rob
RAF Halton Brat - 96th Entry
http://www.halton96th.org.uk/robs_rails.html
β-tester

Stano100
Posts: 13
Joined: Sun Nov 11, 2018 9:41 am

Re: First dcc converted loco start stop

Postby Stano100 » Fri Dec 28, 2018 1:26 pm

Hi again

I have picked up some Zen 8 pin nano decoders with stay alive

I have wired the new decoder and the loco runs fine over the points even at relatively low speeds.
it seems to take a long time stop about 15 seconds, would that be due to the stay alive?

User avatar
End2end
Posts: 4302
Joined: Sun Jan 12, 2014 9:58 pm
Location: At the end....... and sometimes at the other end

Re: First dcc converted loco start stop

Postby End2end » Fri Dec 28, 2018 2:32 pm

Stano100 wrote:Hi again

I have picked up some Zen 8 pin nano decoders with stay alive

I have wired the new decoder and the loco runs fine over the points even at relatively low speeds.
it seems to take a long time stop about 15 seconds, would that be due to the stay alive?

No thats probably something to do with the decoders settings (CV's).
Check the paperwork that came with the decoder to see which CV number controls "slow down" or "Stopping distance" something like that.
Thanks
End2end
"St Blazey's" - The progress and predicaments.
Welcome‎
Planning
Building
St. Blazey's Works & Depot thread

Bigmet
Posts: 6660
Joined: Tue Aug 14, 2007 2:19 pm

Re: First dcc converted loco start stop

Postby Bigmet » Fri Dec 28, 2018 4:20 pm

That's CV4. It provides a decent inertia simulation, and goes unused by most who operate with DCC. Which is a shame because it does far better at representing the effect of all that mass smoothly slowing before coming to rest, than what is typically achieved by manual operation

pauliebanger
Posts: 62
Joined: Thu May 05, 2011 10:07 am

Re: First dcc converted loco start stop

Postby pauliebanger » Fri Jan 04, 2019 12:35 am

GWR_fan wrote:
Stano100 wrote:...............What is a stay alive?
Thanks


Only downside is that with a stay alive the analogue (DC) function on the decoder must be disabled using CV29.



Not if you use a ZIMO decoder you don't. ZIMO's decoders work fine on DC with stay alives fitted.

Best regards,

Paul

User avatar
Mountain
Posts: 3922
Joined: Mon Oct 24, 2016 3:43 pm
Location: Somewhere in Wales, UK.

Re: First dcc converted loco start stop

Postby Mountain » Fri Jan 04, 2019 1:35 am

I believe the original issue can be solved by disabling any inertia and back EMF settings on the decoder. (Experiment with the settings with the decoder). I had a loco doing this that had a ringfield motor and after some programming experimentation it now runs fine. Just as good as it did on DC.
It was only a few comments via more experienced modellers in forums like this that I remembered reading about the solution, so I tried it and it works great.


Return to “DCC Forum”

Who is online

Users browsing this forum: No registered users and 2 guests