Kernow GWR steam rail motor

[cctransuk]

10 minutes ago, melmerby said:

I thought it picked up on all wheels?

That's 8, well spaced out, surely more than enough to get over the biggest interruption.

 

There does seem to be an increasing obsession amongst DCC users to add stay-alives to anything and everything.

 

If track is laid with care and pick-ups are adjusted and maintained, there should be no need for auxiliary power.

 

After all, we DC users manage without them.

 

CJI.

[Oldddudders]

I think DCC sound users probably wish to hedge their bets. Often, if a decoder loses power momentarily, the sound sequence resets to the start, rather spoiling the illusion.

[Harlequin]

1 hour ago, cctransuk said:

 

There does seem to be an increasing obsession amongst DCC users to add stay-alives to anything and everything.

 

If track is laid with care and pick-ups are adjusted and maintained, there should be no need for auxiliary power.

 

After all, we DC users manage without them.

 

CJI.

 

7 minutes ago, Oldddudders said:

I think DCC sound users probably wish to hedge their bets. Often, if a decoder loses power momentarily, the sound sequence resets to the start, rather spoiling the illusion.

 

Yep, not really needed for the SRM because of its multiple pickups and long wheelbase. You'd be really unlucky to completely lose power with these if your track is up to any decent standard.

 

On the other hand, it's so easy to add to the SRM because there's loads of space right next to the decoder. So if you've got the parts and 5 minutes to spare, why not?

 

 

[cctransuk]

5 minutes ago, Harlequin said:

On the other hand, it's so easy to add to the SRM because there's loads of space right next to the decoder. So if you've got the parts and 5 minutes to spare, why not?

 

Are these stay-alives cheap, then?

 

CJI.

[Andy Keane]

23 minutes ago, Oldddudders said:

I think DCC sound users probably wish to hedge their bets. Often, if a decoder loses power momentarily, the sound sequence resets to the start, rather spoiling the illusion.

That is exactly why I do it if it’s easy. Little effort and the sound does not reset as noted by others.

[Andy Keane]

Just now, cctransuk said:

 

Are these stay-alives cheap, then?

 

CJI.

Cost depends on how you do it. Varies from a few pence to twenty five pounds. A simple electrolytic cap is very cheap if the decoder supports it. A low voltage system with super caps is more involved. But given a loco costing around three hundred pounds then I am happy to do it if it’s not too painful. I don’t really understand why all RTR sound fitted locos don’t have them as standard.

[outatime]

Just for information, I've got one with factory sound and the chuffs came way too often.

I adjusted the Chuff-rate, so that there are approx. 4 chuffs in one revolution.

CV 267 was set to 125 in my case which comes close enough for low speeds.

If you want to go back to the factory setting set the CV to 108.

[Andy Keane]

I too had to change the chuff rate to get it right and in my case needed 135. I have also used the trusty Myford to make a replacement chimney - probably not quite the right profile but at least she no longer looks bereft, though it will need a touch of paint down the middle:

[Michael Hodgson]

2 hours ago, cctransuk said:

 

There does seem to be an increasing obsession amongst DCC users to add stay-alives to anything and everything.

 

If track is laid with care and pick-ups are adjusted and maintained, there should be no need for auxiliary power.

 

After all, we DC users manage without them.

 

CJI.

You've also got fingers to poke them with when they stall 🤣

[Andy Keane]

1 hour ago, Harlequin said:

multiple pickups and long wheelbase

Phil, as far as I can see it only picks up from the two driving wheels, with therefor an incredibly short wheelbase. But maybe my eyes are deceiving me.

[cctransuk]

7 minutes ago, Michael Hodgson said:

You've also got fingers to poke them with when they stall 🤣

 

What? I didn't know that there was a DCC initiation ceremony which involved the removal of fingers?!? 😱

 

CJI.

[Harlequin]

5 minutes ago, Andy Keane said:

Phil, as far as I can see it only picks up from the two driving wheels, with therefor an incredibly short wheelbase. But maybe my eyes are deceiving me.

 

The pickups in the trailing bogie are in the axle bearings.

 

[sjgardiner]

On 24/02/2024 at 10:02, Andy Keane said:

While I had mine apart to add some passengers and crew I have added a Staco stay-alive kit. Plenty of room for this above the ceiling. This gives a couple of seconds of power-free running which helps given there are not that many wheels picking up power.

Not familiar with Zimo decoders and Staco keep alives as they are not common in NA, I found the YouChoos site selling them, which version of the keep alive is this you installed? Will want one for my sound equipped once Kernow gets to my order and it wings its way across the ocean. 
 

I need to get on getting my ModelU crew figures painted so I only need to open it up once when I do have it to install the crew and the keep alive.

 

Thanks,

 

Stephen Gardiner

Toronto, ON, Canada

[34theletterbetweenB&D]

1 hour ago, Harlequin said:

On the other hand, it's so easy to add to the SRM because there's loads of space right next to the decoder. So if you've got the parts and 5 minutes to spare, why not?

If sound decoders don't come with a 'resume sound on last output' in event of brief power interruption, then I suppose that is some justification. But the 'why not' is masking of a problem.

 

Early in my DCC experience I tried the Lenz USP module and it did all that was claimed. But totally redundant if track, wheels, pick ups were all soundly arranged; the permanent higher voltage supply 'gets through' so that the loco reliably starts with a creep into motion and continued dead slow if required (and if the most challenging aspect is good, everything else will be). When there is a power loss, even momentary, I want to know about it and fix the cause. At this time of year insects reviving to operational status is quite frequen,t and removing mushed butterfly, moth or wasp is a good plan, before the gunk is spread around.

[Harlequin]

5 minutes ago, 34theletterbetweenB&D said:

If sound decoders don't come with a 'resume sound on last output' in event of brief power interruption, then I suppose that is some justification. But the 'why not' is masking of a problem.

 

Yep, good point.

 

[Andy Keane]

43 minutes ago, sjgardiner said:

Not familiar with Zimo decoders and Staco keep alives as they are not common in NA, I found the YouChoos site selling them, which version of the keep alive is this you installed? Will want one for my sound equipped once Kernow gets to my order and it wings its way across the ocean. 
 

I need to get on getting my ModelU crew figures painted so I only need to open it up once when I do have it to install the crew and the keep alive.

 

Thanks,

 

Stephen Gardiner

Toronto, ON, Canada

The decoder in the Railmotor will accept any kind of capacitor that will tolerate track voltage. However these days I use zimo Staco kits as they allow low voltage high capacity super caps to be used. In my case I used a Staco 3b kit as I had one in my loco modelling tin. It allows a pair of one farad super caps to be used. These kits  are £23 in the uk and give around two seconds of running power with sound. A cheaper option would be say a 17,000 Micro farad cap for a few pounds but this gives much less storage.

Edited February 25 by Andy Keane

[melmerby]

1 hour ago, Andy Keane said:

The decoder in the Railmotor will accept any kind of capacitor that will tolerate track voltage.

Where is it connected?

The Plux21 connector has the +ve & -ve supply rails available but you should not connect a big cap straight across these as there is no charge current regulation and the surge could blow the rectifier.

However using a current limiting resistor with a reverse biased rectifier across is OK. when current is needed it will flow from the cap via the now forward biased rectifier to keep the decoder alive.

Edited February 25 by melmerby

[Andy Keane]

1 hour ago, melmerby said:

Where is it connected?

The Plux21 connector has the +ve & -ve supply rails available but you should not connect a big cap straight across these as there is no charge current regulation and the surge could blow the rectifier.

However using a current limiting resistor with a reverse biased rectifier across is OK. when current is needed it will flow from the cap via the now forward biased rectifier to keep the decoder alive.

There are two solder tabs at the other end of the decoder specifically designed to take stay alive caps. This is a regulated supply to prevent inrush and to take DC back to keep the decoder running. Have you downloaded the Zimo manual: http://www.zimo.at/web2010/documents/MS-Sound-Decoders_EN.pdf see page 7, it’s an MS450.

It’s all explained in there. It takes a steady hand to solder onto these tabs. If you overdo the heat you can destroy the decoder.

Edited February 25 by Andy Keane

[melmerby]

3 hours ago, Andy Keane said:

Have you downloaded the Zimo manual: http://www.zimo.at/web2010/documents/MS-Sound-Decoders_EN.pdf see page 7, it’s an MS450.

No, I am using a Lenz decoder.

 

In the past I have provided a stay alive on a decoder by adding the circuit I mentioned direct across the +ve & -ve but not on the Railmotor.

It was for a camera car where I wanted the ultrabright LEDs on the front to be stable

Edited February 25 by melmerby

[mikesndbs]

Bright head/tail lights.

 

Hi guys good afternoon.

I had to send my first No85 back as the head/tail lights failed :(

Kernow exchanged for a brand new one and I'm only just adding passengers and crew now due to other issues at home.

I have however run the model in and noticed that the head and tail lights are very bright. I'm concerned they will pop again and of course they look wrong.

 

My plan was to add 680 ohms in series with the +pin that comes down from the roof and along with two others presses into pads on the PCB.

The LEDs have 6k8 smc resistors.

I don't want to fix anything so I had used a 1/8th resistor with its legs connected to two bits of foil and an insulator between the foil.

The thought was that the pin would come down and press onto one and hold the other to the pad, but I'm worried if there is sufficient spring in the pin to allow this?

 

Thoughts please?

 

Also does anyone know if the additional resistor could be fitted to the dcc blanking plug which I assume controls lighting? If so which pins. Many thanks

 

 

 

 

[nightstar.train]

I’ve finally got my SRM after retrieving it from parcel purgatory. What an absolutely beautiful model, completely stunning. However, mine is unfortunately a lumpy runner. It seems to be when the left hand cylinder is all the way rearward and starting to move forwards there’s a slight binding. The motor powers through it, but there’s a noticeable jump when it does. Happens both in forward and reverse. I don’t have time right now to trawl back through a few dozen pages, but has anyone else had similar? Is there a simple/easy way to fettle it rather than return to Kernow? 

[melmerby]

On 26/02/2024 at 14:30, mikesndbs said:

Also does anyone know if the additional resistor could be fitted to the dcc blanking plug which I assume controls lighting? If so which pins. Many thanks

Pin 7 is the front light & Pin 13 is the rear light.

For DC diodes go from the track pins to the light pins, so that they are directional and also includes resistors for current limiting. Not required!

I can't check my blanking plug as it is the railway room at the bottom of the garden.

I'm using DCC and the default CV value is 255, when they are like searchlights.

I have reduced that to 32 which is nominally 1/8th as much voltage, so you will need a much larger value resistor than the ones on the blanking plug. Circuit board

Are you able to unsolder surface mount devices, if so you could replace the original ones with a value maybe 4 - 8 times the original value and see how it is.

Edited March 2 by melmerby

[mikesndbs]

Keith thank you, very helpful.

The dcc blanking plate just has four diodes on it! I was looking at R14 on the pcb (200R) but I think this is more to do with the coach lighting than the lamps.

Because we have this weird white pcb its very hard to trace the tracks to see what's going on. I've asked Kernow if they would share the diagram for the lighting at least. 

There must be a simple change that could reduce the brightness and protect the LEDs but so far I can't see it and of course all this SMD makes life very hard.

 

[Andy Keane]

28 minutes ago, mikesndbs said:

Keith thank you, very helpful.

The dcc blanking plate just has four diodes on it! I was looking at R14 on the pcb (200R) but I think this is more to do with the coach lighting than the lamps.

Because we have this weird white pcb its very hard to trace the tracks to see what's going on. I've asked Kernow if they would share the diagram for the lighting at least. 

There must be a simple change that could reduce the brightness and protect the LEDs but so far I can't see it and of course all this SMD makes life very hard.

 

If you want to turn down all the lights perhaps place a resistor between the wheel pickups and the main board?

[Harlequin]

9 hours ago, nightstar.train said:

I’ve finally got my SRM after retrieving it from parcel purgatory. What an absolutely beautiful model, completely stunning. However, mine is unfortunately a lumpy runner. It seems to be when the left hand cylinder is all the way rearward and starting to move forwards there’s a slight binding. The motor powers through it, but there’s a noticeable jump when it does. Happens both in forward and reverse. I don’t have time right now to trawl back through a few dozen pages, but has anyone else had similar? Is there a simple/easy way to fettle it rather than return to Kernow? 

Yes, I have one that lurches through a stiffness in the motion. It used to run basically smoothly but was sent back to Kernow for a slightly different problem and came back with the stiffness.

 

Check that your valve stems and stem guides are horizontal and fixed properly. They seem to become bent upwards quite commonly and that means that the motion is not moving as intended, which might be causing your problem.

 

I haven't yet diagnosed my lurcher. I tried lubrication and a bit more running in but it still does it.