Hornby Select and peco surface points

[Daveeho]

Hello, 

I am a newbie to the site, and have returned to model railways after at lot of years, things have changed! I am setting up a layout in dcc and have fitted some Peco surfance mounted points, I wired them as instructed back to the Select Control unit via a switch, they work, but on switching the Select resets and puts me in to start up mode ( 3 ) and if I am using another LA I have to re-enter that number - why is this? Your help would be greatly appreciated.

David

 

[RB51]

Hello Dave - welcome to the forum.

 

Are you operating your points via DCC command or the alternative DC supply of the Select? It sounds as though the Select is seeing a short and re-setting itself.

 

R-

[Chrissaf]

David, welcome to the forum.

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By switch, I assume you mean a physical electrical switch and NOT a DCC Accessory Decoder.

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I am also assuming that you are using the auxiliary output of the Select controller. The output terminals on the right hand side as looking towards the back panel.

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On the basis that these two assumptions are correct:

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The power supply unit supplied with the Select is only rated at 1 amp, only a proportion of this current is available for this auxiliary output, and is inadequate for operating the points directly. A solenoid point motor has a very low impedance (resistance) and is a device that requires a very high initial operating current. Typically about 4 amps.

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The bottom line is that by connecting the surface mounted Solenoid point motor via an electrical momentary switch to the Select, you are overloading the Select power supply by trying to draw too much current through it and its attached 1 amp power supply is resetting, causing the Select to restart.

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Personally, I would use a dedicated separate power supply for the points. A laptop 19 volt DC switch mode power supply is ideal and can be purchased very cheaply indeed.

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However, you will probably be able to continue using the Select as a power source if you modify your point wiring and connect a Capacitor Discharge Unit [CDU] to the auxiliary output of the Select and use the output of the CDU to connect to your point switches and wiring.

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A CDU is a power storage device that charges up relatively slowly thus the current load it will place on the Select power supply will be relatively small by comparison to the way that you currently have it wired up. The storage capacitors within the CDU store lots of electrical energy and it is these capacitors that provide the very high currents that the Solenoid point motors require. Once a point has been thrown, the capacitors within the CDU recharge drawing a much lower current. The recharge time is typically 1 or 2 seconds. CDUs cost relatively little to purchase ready made.

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You can see some general point wiring diagrams using CDUs here.

http://www.brian-lambert.co.uk/Electrical.html#Motor

[Daveeho]

Many thanks for the speedy replies, it had crossed my mind that the power output was not sufficient, but I was not confident that this was the cause, I had been considering purchasing a 4 amp power supply for the Select, as I intend to operate more than 3 loco's, would this overcome the problem or is it still a better option to have a dedicated auxilary supply or even buy an Elite controller.

 

David

[Chrissaf]

The Elite is a red herring, it won't do anything more for you in terms of managing power to the points. The 4 amp power supply replacing the 1 amp supply will certainly help, but I think you will find that installing a CDU as per my previous post will more likely resolve your issue.

[Fishmanoz]

You'll also find the Select will drive more than 3 Locos unless you are trying to run all of them flat out at the same time.

[81F]

 I now use an elite but did start off with a select. However, my points were and still are powered by a separate 16V AC output from an analogue (or DC) controler via a Capacitor discharge unit so I've never had a problem so would recommend a separate power suppliy but with a CDU as well.