Kernow GWR steam rail motor

[melmerby]

59 minutes ago, Deltaskelta said:

Update Sat 3rd Feb.  Many thanks, Kernow.  Replacement arrived by return of post and running perfectly, including over the branch line curves and the "crossover from hell".  Brian

Same here, my replacement arrived at lunchtime, just off to the Railway Room to check it.

 

Nice they didn't waste the box & packaging which has now done three trips with Royal Mail

[melmerby]

Replacement on rolling road, running nice and smooth on around 6v DC

[didcot]

Mine seems to have gone to the Midlands super hub instead of heading south for replacement.

[melmerby]

Something mentioned earlier.

I found getting the body off and back on again after fitting a decoder, is not the easiest task.

Things tend to obstruct the refitting and I was surprised I didn't damage something.

 However it runs really well, nice and smooth & quiet.

 

Query

How do I turn the stay alive off, or at at least reduce it?

Edited February 3 by melmerby

[Chuffer Davies]

35 minutes ago, melmerby said:

Something mentioned earlier.

I found getting the body off and back on again after fitting a decoder, is not the easiest task.

Things tend to obstruct the refitting and I was surprised I didn't damage something.

 However it runs really well, nice and smooth & quiet.

 

Query

How do I turn the stay alive off, or at at least reduce it?

I’m not aware that a stay alive can be turned off unless it is disconnected. It is connected to the common rails and is not (for instance) switchable by CV changes.    Reducing it would require replacing the capacitor with a lower value.  What is the problem that is concerning you with the stayalive?

Frank

[Oldddudders]

1 hour ago, Chuffer Davies said:

I’m not aware that a stay alive can be turned off unless it is disconnected. It is connected to the common rails and is not (for instance) switchable by CV changes.    Reducing it would require replacing the capacitor with a lower value.  What is the problem that is concerning you with the stayalive?

Frank

I think it is a problem encountered by those who use computer control, rather than just DCC. They clearly rely upon predictable performance by every loco, and the stay-alive may inhibit this. 

[melmerby]

2 hours ago, Chuffer Davies said:

I’m not aware that a stay alive can be turned off unless it is disconnected. It is connected to the common rails and is not (for instance) switchable by CV changes.

You can with an Accurascale Manor.

What you do is set how long it runs for if the supply is lost using a CV.

The Kernow SRM behaves a little different as it stops dead if you remove the supply but cruises on for some distance if you drop the speed to zero. I have set acceleration and deceleration CVs to zero.

 

Unless of course it's not a stay alive........

[melmerby]

Problem Solved. SRM now behaves as wanted.

When I set CV3 & CV4 to zero, for some reason it hadn't taken effect.

Have now done it again and is now correct so it's not a stay alive problem!

Edited February 4 by melmerby

[Chuffer Davies]

14 hours ago, Oldddudders said:

I think it is a problem encountered by those who use computer control, rather than just DCC. They clearly rely upon predictable performance by every loco, and the stay-alive may inhibit this. 

That's not what the Stayalive does. Its purpose is to maintain power to the chip in the event track current is temporarily interrupted.  The chip is just like any other computer-like processor and goes back to its start configuration (resets) if power is interrupted.  This is particularly annoying when you have a sound chip fitted as the loco will go through all the start up sounds before it gets going again.   Stayalive just lets the chip continue to perform the last instruction it received be that continue, speed up, slow down, finish blowing the whistle, etc.  Its ability to supply traction current is critically dependent upon the capacity of the device.  It wont keep supplying power indefinitely but it usually only needs to maintain traction current for a split second before the supply is restored.  The more power hungry the demand the less time it will be able to maintain current for. 

 

I can't think of any situation where the Stayalive will have a negative effect except when the panic button is pressed because in my experience locos fitted with a Stayalive will continue to run until the capacitor is exhausted  which may mean it doesn't stop in time to avoid the disaster you hit the panic button for in the first place.  

[woodenhead]

17 hours ago, Chuffer Davies said:

I’m not aware that a stay alive can be turned off unless it is disconnected. It is connected to the common rails and is not (for instance) switchable by CV changes.    Reducing it would require replacing the capacitor with a lower value.  What is the problem that is concerning you with the stayalive?

Frank

Stay Alive can be adjusted with CV settings to that for example your loco doesn't go on a long march in the event it ceases to be in contact with it's controller, you can set it to just utilise a second's worth of Stay Alive juice.

 

Hitting the red 'all stop' button on my on NCE Powercab stopped locos fitted with Stay Alive provided the locomotive is still in contact with the controller (i.e. on the track).

[Chuffer Davies]

8 minutes ago, woodenhead said:

Stay Alive can be adjusted with CV settings to that for example your loco doesn't go on a long march in the event it ceases to be in contact with it's controller, you can set it to just utilise a second's worth of Stay Alive juice.

 

Hitting the red 'all stop' button on my on NCE Powercab stopped locos fitted with Stay Alive provided the locomotive is still in contact with the controller (i.e. on the track).

Does it depend on whether the chip has the Stayalive control built in or whether a separate interface has been used?  I use small Zimo decoders which need a separate interface wired directly to the common (supply) rails on the chip. I don’t see how the chip could then differentiate from power supplied via the track and power being taken from the capacitor.

[woodenhead]

@Chuffer Davies I've not yet done it to my locos so the ones that are Lais fitted run for several seconds after being removed from power and I should really do something about it.

 

But in all cases the power is not coming to the chip via the main power in feed, it is coming from the Common/Ground or Common/Capacitor connections so the chip should know where the power is arriving from.

 

@Nigelcliffe Knows a thing or two about this stuff.

[melmerby]

2 hours ago, Chuffer Davies said:

The chip is just like any other computer-like processor and goes back to its start configuration (resets) if power is interrupted.

Although sound start up sequences are reset, other settings such as speed are not "reset" as such, as the decoder  reacts in real time to what is being sent on the DCC bus.

If I cut the power when on maximum speed (without reducing speed setting to zero) , when the power is restored the decoder goes straight to maximum speed again as that is what is being sent on the bus.

This assumes CV3 & CV4 have been set to zero.

[melmerby]

2 hours ago, Chuffer Davies said:

 I use small Zimo decoders which need a separate interface wired directly to the common (supply) rails on the chip.

I don't think so.

The aforementioned Accurascale Manor has a built in stay alive and you can adjust how long it runs for with a CV on a Zimo decoder.

I've got two, one uses an Zimo MX6i8N18 and the other has a later Zimo MN version.

 

The post rectifier supply rails are part of the Next 18 decoder specification.

 

Also on Plux 22 (as used in the SRM) & Plux 16.

 

The Lenz Silver Plux 22 I have uses CV112 to set stay alive time if a capacitor is supplied.

Edited February 4 by melmerby

[Harlequin]

2 hours ago, Chuffer Davies said:

Does it depend on whether the chip has the Stayalive control built in or whether a separate interface has been used?  I use small Zimo decoders which need a separate interface wired directly to the common (supply) rails on the chip. I don’t see how the chip could then differentiate from power supplied via the track and power being taken from the capacitor.

The Zimo stayalive time controls work for external stayalive circuits.

 

The decoder rectifies and smooths the DCC waveform from the track to become its main +ve and gnd power supply. It also watches the DCC signal for commands. So if that command signal disappears but there's still power between +ve and gnd it must be running on stay alive and it can start its timers.

 

BTW: Decoders (at least current ones) are not just computer-like - they really are computers. Zimo MN and MS decoders have ARM cores in them, running the same instruction set as most mobile phones.

 

Edited February 4 by Harlequin

[Nigelcliffe]

4 hours ago, Chuffer Davies said:

Does it depend on whether the chip has the Stayalive control built in or whether a separate interface has been used?  I use small Zimo decoders which need a separate interface wired directly to the common (supply) rails on the chip. I don’t see how the chip could then differentiate from power supplied via the track and power being taken from the capacitor.

 

They can, and they do differentiate between track-power and stay-alive power.   Read the Zimo manuals :-).    There are settings for "run time without DCC signal", which would be sensible to set quite low in most situations.     I'd expect any decent decoder design to include run-time settings for stay-alives.

 

The benefits of a large stay-alive are two-fold.  Firstly, the voltage won't decline by a significant amount in normal use, and secondly (on Zimo only), should the loco come to a stop and as it stops it looses track power, then the decoder senses the loss of DCC and deliberately nudges the loco a bit further until DCC is restored or it is out of power.  Moving a motor from stop takes a lot of current. 

 

 

 

Any reasonably decoder should respond to an E-Stop signal (which is the emergency stop on many systems), and stop instantly.  

 

 

- Nigel

 

 

 

 

[Methuselah]

Mine is on it's way. I ordered the DCC sound option. Do I need to remove the decoder and fit a blank to run it on DC - or will it just run on DC anyway automatically....? I don't want to risk damage....

[Kernow MRC]

GWR Steam Railmotor Update
We can advise that the last non-sound pre-ordered Railmotors will be sent out by the end of today (05/02/24), and we are continuing to complete the pre-orders for sound-fitted models. These models are fitted at our workshop and we currently still have over 500 to fit so please be patient!
We have updated our dedicated project page here  https://www.kernowmodelrailcentre.com/pg/144/KMRC-Locomotive---GWR-Steam-Railmotor

[Kernow MRC]

3 minutes ago, Methuselah said:

Mine is on it's way. I ordered the DCC sound option. Do I need to remove the decoder and fit a blank to run it on DC - or will it just run on DC anyway automatically....? I don't want to risk damage....

 

As stated on our dedicated page here https://www.kernowmodelrailcentre.com/pg/144/KMRC-Locomotive---GWR-Steam-Railmotor

 

DCC Sound running on DC information: The Railmotor sound project will produce all automatic sounds on DC the same as under DCC – this includes chuffs, start-off release, come-to-halt sounds, and certain random sounds. As with any sound decoder running under DC, the decoder kicks into life above a threshold voltage – somewhere between 5V and 9V, so you will be running the loco in the top part of your throttle’s voltage range, but otherwise is quite controllable.

[sjrixon]

Thanks.. Great update.. I'm in that final 500 then! Not long now..

Edited February 5 by sjrixon

[stephennicholson]

2 hours ago, sjrixon said:

Thanks.. Great update.. I'm in that final 500 then! Not long now..

 

Likewise. Out of curiosity I wonder how long it takes to do each one - they will be doing it their sleep with that number to do!

[JSpencer]

2 hours ago, sjrixon said:

Thanks.. Great update.. I'm in that final 500 then! Not long now..

 

Me too, not long now.

[Mikkel]

Lovely runner, until this happened:

 

 

 

Looks like a direct break, nothing untoward prior to this happening, the otherwise lovely model just running in quietly at half speed. Happened after about 25 minutes running.

 

Return label doesn't seem to work for overseas orders, but I have no doubt it will be sorted via e-mail. Import fees due again though.

 

[Mikkel]

Just had a close look. Methinks the link is plastic. Can anyone confirm?

[Colin_McLeod]

2 hours ago, Mikkel said:

Return label doesn't seem to work for overseas orders, but I have no doubt it will be sorted via e-mail. Import fees due again though.

 

There is a procedure/form filling for warranty returns without having to pay import fees again.  Your post office or Kernow themselves should be able to advise/assist.