More wiring help needed

[Anonymous]

Hi Everyone, and Happy New Year. I need some help. I am building my 3rd layout after a long hiatus. I have a Tech II model 2500 power pack and have run two 14 guage bus lines under my layout (about 25 foot lenths each, black and red). Attached to these are 18 and 22 guage feeder wires in sections approx 3 feet apart. I have tried to carefully solder the feeders to the correct rails and then to the bus lines. But when I go to connect each bus line to the variable DC terminals and turn the power pack on, I get no power whatsoever. After about one minute, the "overload" light comes on the power pack. I have an ACDC multitester, but in order to test each soldered joint, I would have to keep the power pack plugged in. According to the MRC Tech manual, keeping the pack on with the overload light will quickly damage the pack. How can I check each connection with my multitester while keeping the power surging in the bus lines to do it? Any advice is appreciated.
JP

[Anonymous]

John,

I can only guess what has happened from your description but it sounds as if you have a short in your wiring. Either you have a reversing section that you didn't realize was there or you connected one or more feeders to the wrong bus wire. The only reason I can guess that your overload doesn't come on immediately is that you may have the momentum control on and the overload is not triggered at very low RMS voltage. Go over your feeders and make sure they are attached to the correct bus and then check your track plan for any reversing sections. Sorry I can't do any better than that. Good Luck - Ed

[BR60103]

How are you testing it that you need the pack turned on? Have you tried testing with the Ohms side of the meter?
To protect the pack a bit more you could wire an automobile bulb in series with the layout to absorb the current. Or some bulbs from a christmas tree string. (You can get these very cheaply this week or use some you can't get replacements for. Use a series string and take one tenth of it to get 12 volts worth of bulbs.)
--David

[Anonymous]

Hello JP,

There's a short circuit, or perhaps more than one, somewhere. Possibly it's a feeder connected to the wrong bus.

Another possibility has to do with turnouts: Are they selective routing or do they have insulated frogs? If they're the former, you'll need to cut gaps in the rail after the frog wherever a turnout is used for a crossover or passing siding. I typically cut gaps (with a cutting disk in a motor tool) about an 1-1/2" or so from the point of the frog. You can also use insulated rail joiners.

Those are two items I'd investigate before breaking out my multimeter. Using the multimeter, however, you should be able to check for a short circuit by measuring resistance. With the bus wires disconnected from the power pack place a multimeter lead on each rail. You should get an open circuit reading. My assumption is that the meter will register a short circuit, however. Then you're going to have to trace the circuits and check the turnouts for inadvertent short circuits. This may eventually involve unsoldering some connections (which is why using a terminal/barrier strip between feeders and the bus is a good idea).

Hope this helps, and don't be discouraged: I was scratching my head the other day over short circuit. Cut a gap in particular turnout (one I hadn't earlier considered would cause a problem)just past the frog and the trouble disappeared.

Paul Schmidt
Contributing Editor
Trains.com

[Anonymous]

Paul, thanks for the advice. I do have insulated frogs on my turnouts (Atlas), so I will try and find the shorts and also use the resistance idea. Hope I find it like you did.

JP

[Anonymous]

Ed, your suggestion is a good one, as are David's and Paul's. Thanks.

JP

[Anonymous]

John,

My pleasure to be of assistance. Did you find the problem?

Choo - Choo!

Ed

[Anonymous]

Paul, your suggestion on a gap near the turnouts was correct. I kept thinking that since I had insulated frogs I did not have to gap. But I went ahead using Andy Sperandeo's guide in his electrical book...and it worked. My overload light finally stayed off and I was running trains...what a thrill and relief after such frustration. Thanks again and Happy New Year!

[Anonymous]

Great news! Andy's book is terrific, isn't it?

Paul