Shorting out

[mecmt]

O scale, 2 rail.  I have 3 engine, 2 Atlas and 1 Weaver.  I also have 9 lighted passenger cars, 4 Weaver Bradley, and 5 zephyr cars. Recently when turning the power on to the track with a PWR-56 it goes into a short reset short cycle. If I take all the cars and engines off the track, turn the power on then add everything back to the track, no short.  Turning on, with all the above mentioned on the track results in the short, reset, short cycle. I am hoping someone can help.  This did not start doing this when I first hooked up the PWR-56.  The engines all have LM-3S-G. The Weaver cars are 2 rail factory cars with some kind of keep alive, as the lights stay lighted without power for about 15 to 30 seconds after power off.  The Atlas cars are also factory cars.  The PWR-56 is plugged into a switched power strip.  Any thoughts?   

[Alan]

Sounds like the surge power required at start-up is exceeding the PWR56 output limit. What happens if you leave the keep-alive equipped lighted cars off the track during start-up? Will the PWR56 start-up with just locos and unlit cars on the track?

[mecmt]

That is what appears to be happening.

[mecmt]

Any Ideas on how to deal with this. It did not do this at first, with 1 engine and 4 cars, now everything except for 1 engine will start the shorting cycle.  The 4 cars where the Weaver.

[Alan]

There are all sorts of start-up circuits called 'soft start' that slowly turn on the power to prevent the instant on surge. Rather than invest in a soft start circuit, a better solution would be to use a higher rated power supply as it sounds like you are pushing the limits of a PWR56. That is not at all surprising with O scale trains. Ring doesn't offer so you would need to go outside RailPro for one. There are many to pick from on eBay. Here is an example: https://www.ebay.com/itm/DC15V-3A-5A-10A-20A-30A-Switch-Power-Supply-Monitor-Centralized-Power-Supply-LED/362408881915?hash=item546140aefb:rk:5:pf:0&var

In the mean time you can use a switch and a resistor to make your own manual soft start. Turn the switch off, turn on the PWR56, wait 1 second, turn the switch on. When the switch is off (open) current will flow from the PWR56 through the resistor to the track. The resistor limits the amount of current that flows to a level below the PWR56 short circuit protection trip point. Once all the keep-alive circuits in the rolling stock finish charging the current demand drops to a level the PWR56 can handle. When the lights come on in the rolling stock the keep-alives have finished charging. Turning the switch on (closed) bypasses the resistor allowing normal operation. You will need to remember to turn the switch off before powering up the PWR56 each time.



Use virtually any single pole single throw (SPST) toggle switch rated at least 5 amps (will be marked on side). Use a 5 ohm 100 watt resistor.

Resistor: https://www.ebay.com/itm/50W-100W-0-01-50-Ohm-Shell-Power-Aluminum-Housed-Case-Wirewound-Resistor-New/162961019268?hash=item25f13bd184:m:mY-wkIfgcVQ8wv-unNLSrmg:rk:4:pf:0

[mecmt]

Thanks for the help Alan.  I understand the resistor with the wiring diagram. So lets discuss the power pack.  Would I use this in place of the PWR-56.  I am thinking I would.  Do they come with a diagram on how to wire it up.

[Alan]

Easy peasy. The power supply will have screw connections for 115 AC in and + - 15V DC out.

Here is a pic I found on the web. It is typical of the connectors found on almost all made in China power supplies.



Do not do any wiring with a cord plugged into a wall socket!!!

The 'L' stands for line and is where you connect the black wire of an AC power cord. The black wire is the narrow blade on the plug.
The 'N' stands for neutral and is where you connect the white wire of an AC power cord. The white wire is the wide blade on the plug.
The ground symbol is where you connect the green wire of an AC power cord. The green wire is the round 3rd pin on the plug.
Each of the above are high voltage house current. Cover the connections so they can never be accidentally touched or shorted together. The shock will knock your butt across the room. Use a 3 prong AC plug. Do not use a 2 prong AC plug.

The 'COM' stands for common. It is often referred to as DC ground or zero DC volts (not to be confused with the ground symbol on the 115V input). COM is the same as the black wire of a PWR56.
The +V terminals are the 15 volt positive output. +V is the same as the red wire of a PWR56.
The two COMs are tied together inside the enclosure. +V1 and +V2 are tied together inside the enclosure. It doesn't matter which you pick. They are the same. Two connections for output are provided for convenience since these power supplies are often used to power more than one device.

[Alan]

Before you buy a power supply or even before you make a switch/resistor circuit, make sure you don't actually have a short circuit on your layout.

Take all rolling stock off the rails. Turn on the PWR56. Add rolling stock to the rails one at a time until all cars and locos are on the rails. Run trains. Everything work okay?

[mecmt]

Thanks for all your help.  I have removed all rolling stock from the train set and added all back on one at a time.  Also in different order, with everything running successfully.  It has been frustrating to say the least.  Again thanks for your help. Although I am still happy with the product, installs easy, programing even easier, sounds great, and engines run great together.  Still glad I made the change.  Although I was wondering and still am if the PWR-56 could supply the power for O scale 2 rail.   

[TwinStar]

Alan, I have some of these not installed yet. What would you recommend to use to cover the L/N/Ground?

[Alan]

Although I was wondering and still am if the PWR-56 could supply the power for O scale 2 rail.   

Yeah, the PWR56 is more well suited to HO. The larger scales tend to be more power hungry. I am guessing your lighted cars use incandescent light bulbs too. That really runs up the current demand. Other than the radio repeater function and, to a much lesser degree, the temp reporting to an HC the PWR56 is not stellar. Much more power for much less money is readily available.

[Alan]

Alan, I have some of these not installed yet. What would you recommend to use to cover the L/N/Ground?

Anything that has sufficient dielectric strength. Kapton tape? Good quality electrical tape? A piece of plexiglass affixed over the whole terminal end of the enclosure?

[TwinStar]

Alan, I have some of these not installed yet. What would you recommend to use to cover the L/N/Ground?

Anything that has sufficient dielectric strength. Kapton tape? Good quality electrical tape? A piece of plexiglass affixed over the whole terminal end of the enclosure?

I was hoping it was that simple. Thanks!

[G8B4Life]

A piece of plexiglass affixed over the whole terminal end of the enclosure?

This is similar to what I did. I used one of these sorts SMPS to create a charging station at work (it works great, one SMPS with 16 charging leads instead of 16 individual plug packs!). The SMPS I bought (MeanWell) had a little plastic clip-cover for the terminals but being a workplace this was not enough so I found an old electrical enclosure and cut it up make a complete shroud for the terminal end of the SMPS. The same thing could be done with a plastic electronics project box. I'll get a photo when I'm at work tomorrow, I forgot to get one today.

I mention this as while tape or no cover at all might be fine for home, knowing Jacob is into Free-mo then if he's at a meet then I'd caution that the meet might becomes a workplace under some sort of law and the terminals would need to be covered properly.

Back to the OP and the PWR-56, I tend to agree the PWR-56 is not really designed for O scale. Infact the documentation for the LM-3S-G doesn't even mention it, only "Ring approved power supply" or battery power.

- Tim

[Alan]

I mention this as while tape or no cover at all might be fine for home, knowing Jacob is into Free-mo then if he's at a meet then I'd caution that the meet might becomes a workplace under some sort of law and the terminals would need to be covered properly.

Very good point. Out in the public is very different than at home in your basement. Safety first!

Additional things to consider when enclosing a SMPS.

• Mount horizontal and provide ventilation. The holes in the factory enclosure are there for a reason. Until you get up into the higher output models, these units use convection cooling i.e. no fans. It is important for the convection air currents to work properly that the unit be mounted horizontally. If you build another enclosure make sure it has plenty of air holes arranged similar to the holes in the original enclosure. Power rating is reduced 50% if you mount a SMPS vertically or on its side. Not a good idea.
• SMPS generate radio frequency (RF) interference. That is why you always see them in metal enclosures or conductive plastic bricks (PWR56 and laptop supplies). This is why it is mandatory to use a grounded AC line cord. The case is connected to the 115V input ground screw connection. A grounded case suppresses RF emission. If you build another enclosure for the power supply make it out of metal as well. Ground it to the original enclosure. Double layer RF shielding will guarantee your SMPS isn't messing with other radio devices at the show.
• Hole diameter matters. Notice the case has a lot of little holes. Use the same size holes for your second outer enclosure. Do not drill big holes and do not cut open spaces. The relationship between the hole diameter and the RF wavelength is specific.

Factoid: The metal case of a SMPS is not 100% effective at blocking RF emission. For loco break-in I have a small SMPS powering a loop of track. Initially, the SMPS sat on the table next to the loop. I discovered that if I held the HC such that the SMPS was in the line-of-sight between the HC and the loco I would immediately lose connection to and control of the loco. The connection would not re-establish when the loco moved around the loop to where the SMPS was not in line-of-sight. The only way to regain control was power down and re-start. Moving the SMPS well below the table so it is never close to line-of-sight solved the problem.