I use a Bachmann Spectrum DC power pack for all of my AC needs, which right now are a handful of 12v bulbs and a 12v signal wired through a switch machine to indicate turnout position. For some reason I wanted to see if an LED I had was 12v, and instead of using a AA battery to see if that would be enough power, I touched it to my two AC bus wires, and it flashed, briefly, then all of my AC power was blown. Now when I turn on the pack (which isn't used for DC, although the DC terminals are wired to my DCC pack to provide an additional throttle, which wasn't being used at the time), no lights go on and there's an occasional click sound, almost like the sound a light switch makes. I figure a fuse is blown, or something like that, but the pack doesn't have a noticable reset switch. Is there one on the inside? Is the power pack useless for AC now?
Thanks
First, the LED: When wiring a LED, you need a resistor in series with the LED to keep it from drawing too much current. I usually start with a 1K (1000 ohm) resistor. Without the resistor, the LED (Light Emitting Diode) will burn out almost immediately, and become a DED (Darkness Emitting Diode.) That sounds like what you've got now.
I suspect that the clicking sound is a circuit breaker inside the power pack. When it clicks on, it still finds the short, and clicks off again. Have you completely disconnected the supply from the layout? Or, could there be a bit of burned-on wire shorting across the terminals from your "experiment" with the LED? This internal breaker seems to be doing what it should, but the short is still there. Once you fix the problem, you should not hear the clicking anymore.
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If you do not understand electronics, next time search using Google for LED voltage or current. Then put the links in your Favorites folder. Most of the time you will find an answer before you get into trouble. Some people have had an LED explode sending small particles flying.
Your pack must have a circuit breaker inside that did not reset. WAG. Look all around the pack for a little plastic pin that pokes though the case. Push the pin.
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.
Thanks for your help. It turns out that one batch of lights (all connecting to the AC bus wires through the same plug) was the reason why the power pack kept shorting out. Unplugging the lights from the bus solved the main problem. Next up is to figure out why those lights are now shorting out.
Also, quick tip if anyone is interested. I have a station with a handful of lights on the interior. I wanted to keep the building removable, so I used two 9volt battery plugs to connect the building to the AC bus wires. This way the building can be unplugged and moved without much hassle. The plugs are pretty cheap from Radio Shack.
Hi!
Regarding the LED hook-ups, the previous posters were "right on", and I would go with their suggestions.
Regarding the power pack, if you cannot find a reset button, unplug it, cut off the cord, and throw it in the trash. You can get replacements easily and cheaply on Ebay or reasonable prices at the LHS. Even if you are familiar with electricity, it just doesn't pay to try to fix a power pack. "Messing" with one could lead to electrical shock and/or a fire - and that's no joke.
Gee, does it sound like I speak from experience??????
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Mobilman44
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mobilman44Regarding the power pack, if you cannot find a reset button, unplug it, cut off the cord, and throw it in the trash.
No no no said the little dinosaur (grandson's videotape). The Circuit breaker is both internal and self resetting. That is what the clicking sound that he heard was. Many CBs are self resetting. They reset after cooling down and will trip again if the short still exists. No outside reset button needed or supplied. The OP did find an external problem.
The only real problem is that the breaker will get stressed after too many open/reset cycles and fall out of calibration - maybe way out. After first open, disconnect load, wait for a reset. If it resets then reconnect the load. If it trips again then the issue is external. Disconnect again and use an ohmmeter to find the problem.
Karl
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