I have a MRC twin Power Supply. The overload indicator light comes on within second of putting on the power and none of the lights work or the couple of snap switches.
1. I have disconnected the wires from the rear and tested the 12v & 18v connections. Both have the proper output.
2. The problem is on the 18v side as I hooked up only the 12V side with no short.
3. I have visually inspected all the connections and do not see any thing wrong.
Next step please
Harold
If I am reading this correctly, when you hook up the 18 volt side which I assume is AC, the overload kicks in. Whatever the 18 volt is feeding has a short.
A couple older MRC supplies I have had, showed a 12 vdc and 16 vac output.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Some of the newer MRC's that you can use for G-Scale,have a 18V to 2OV out,,,,,,But I believe you are correct Rich,,something he is feeding with it whether it be 16v or 18v,is causing the short...
Cheers,
Frank
The question is. How do I find the short?
Disconnect the power from the transformer?
Does it work? Yes (It is OK) or No (it is not ok and must be opened up to fix it.)
You have wires out on your layout that you are connecting to it.
Disconnect all of the wires from your bus, and reconnect them one at at time until it stops working.
Then you will know where the short is.
This is the point where the LION would re-wire the layout. Run two BEAR wires around the layout, and connect your AC accessories to this pair one at a time. Keep it neat and it will work forever.
LOOK, at least the LION *knows* where his GROUND wire is... : )
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Hwolf,
A little more background information would be helpful. Are you hooking up this power supply to your circuitry for the first time, or have you previously used it successfully on your layout? If it used to work correctly but doesn't now, look first at the last thing you added or modified on your wiring. Also visually check your wiring connections and trackwork for obvious shorts, like tools laying across the track or a wiring connection that didn't get insulated, and is touching something it shouldn't be. If none of these procedures help find the trouble, if your circuitry is complicated, disconnect the farthest half and see if things work properly. Then reconnect things until your symptoms reappear.
Wilton.
The layout has been connected for years. Just came back from vacation and it was like this. Trains run fine and there is nothing on the track. I have about 20 lights and 2 snap switches that are being affected.
I plan on doing exactly what you mentioned if I can find an easier way.
WHAT KIND OF LIGHTS???
If they are of the Christmas tree series incandescent, they have a shorting wire inside of them so that when a lamp burns out it will generate a dead short that will keep the other lamps in the set lit.
ROAR
Harold,
I would disconnect,the two snap-switches,first,if it works you know there is a problem with the lights,or disconnect the lights first,,either way one or the other.....If they both don't work,,look at your terminal strip,if you are using one,,maybe a wire is touching somewhere...There is no easy way...
Good Luck!!
Divide and conquer. It's the only way. When I had layouts that got that far, I had lights in nearly every structure. But I always hooked them up to a series of switches, either plain SPST toggle switches, or Atlas Connectors. Couple of structures to each switch, that way I could turn everything off, turn on factories and offices but not houses, turn them all on, turn on just houses - etc. With multiple circuits, you could switch them all off, see if it shorts - if so, problem is the wire between the power pack and the switches. If that's ok, turn on one switch at a time until it shorts - the problem MUST lie within the wiring to the section that shorted when you turned it on. Without switches, you;ll have to disconnect all 20 or so, then connect one at a time until you get a short. The last one you connected, causing the short, is where the problem is.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I used several terminal sprips around the layout. I will start with disconnecting one by one.
Is there any way to measure the voltage output at these points that would show a short?
The only good thing about this it will give me a chance to improve my wiring
hwolfIs there any way to measure the voltage output at these points that would show a short?
You cannot measure voltage because none is present. The circuit breaker opens and stops the current flow.
You can use continuity to check for a short but it will be difficult on your lighting circuit. You will need to unscrew or disconnect every bulb at every socket because the meter will not know the difference between a short and the bulb filaments.
Then you can begin to track down the short circuit. After you remove all the bulbs, you connect a DMM to the lighting circuit at the 2 wires which attach to the pack. The DMM will read continuity due to the short bridging the + and - wires together.
Now you start disconnecting at the terminal strips. When the continuity on the DMM goes open you found your short.
Or you can just leave the bulbs in and keep checking the overload indicator as you disconnect the terminal strips.
Diagnosing a short is different from diagnosing an open. You check for voltage or the lack of to determine an open circuit condition.
To diagnose a short, you already know voltage is not present. So you look for continuity to ground.
Jim
I am planning to disconnect the Terminal Strips one by one. Thanks
Start at the one farthest from the pack, then work towards the pack.
Let us know.....................
Problem found. Of course it was the last wire I checked.
Two wires under a building got fused. I think I will now install switches before each terminal strip.
Glad you found your problem,,,,,,also a good idea to install switches, a lot easier to find problem's..when you can isolate the power distribution..
After thought; probably would be a good idea,to try to find out why the wires fused also,,bare spot,,wire not big enough gauge for current and so forth..
It was the small wires coming from the lamp.
Have a great evening
Great!!
Glad you found it, no more power outages for your town.
Another little trick to help shorten the discovery time:
Break it apart in the middle. If it works, problem is in the second half, if not, problem is in the first half.
Next break in the middle of whichever half is bad from step 1.
and so on.
Let's say the system is: Power supply-------------------------------------|
so, step 1, make it PS--------A-----|--------B------|
Let's say it works with that break between A and B. therefore the trouble must be in B.
So now do this: PS-------A-----*---B1---|---B2----|
* is where we reconnected the break between A and B
Let's say is is still dead. Therefore the problem is between where we made the break in step 1, and the break between B1 and B2, or in other words, in the area B1
If that's a small enough area, you can chech individual connection, if it's still a large area, repeat cutting things in half until you have a workable area that shows a fault.
This works for just about any sort of troubleshooting, and can save a lot of time vs one by one checking every single connection.