My Atlas SD-24 has been working erratically where others have not. Cleaning track, wheels, soldering track , etc. has not cured it. I noticed on the millionth time cleaning its wheels (running it over an alcohol-soaked paper towel) that one truck was having issues picking up power. SO! Not the track. That's good in a way, but now it calls for trouble shooting the loco. Not my favorite task, as electricity is a mystery to me.:tb-confused: Anyway, getting into the innards of the suspect truck - with the help of the diagram Atlas included in the box (thanks Atlas) I get to the wire connection to the wheel wipers. No soldered connection here, but the wires are held onto tabs with plastic wire retainers. Not real solid. Also, the wheel wipers themselves - which are metal frames set into the plastic truck frames withholes that the axle ends ride in - are a blackened metal. To me, this doesn't seem like the best for electric conduction. After burnishing the tabs with a dremel wire brush until shiny, I reassembeled and got the shell back on without destroying any hanrails. Miracle. The nest miracle was that my efforts actually paid off, it runs great now. HOWEVER Now the golden white LED headlight doesn't work. What the....????? I checked its wire connections, they are fine. I removed the bulb and physically connected them to a power source. Nothing. So - is this a simple matter of the bulb burning out at a very inopportune time? Do LED bulbs burn out easily? It's a relatively new loco, although it was old stock from 2006. Is there something I did that caused this? Just wondering if any of you have had experience with this. My next step will be to locate a replacement bulb.
Good that the loco is running as desired. To my knowledge, LED's do not burn out that often but they at some point do. My guess would be somehow to much amperage went tot he LED and burned out. You could create a test circuit with proper resistors to test the LED (does anyone make a handy and cheap LED tester?) Or maybe easier is to just purchase a replacment LED for the loco and rough wire it in (maybe using aligator clips to wires to test prior to soldering it in only to find that the LED is not the problem). So far (knock on wood) I have never had an LED burn out yet either from my N-scale days or my present HO stuff. Granted I have not really ran my HO stuff all that much except at the club once in a while.
LEDs do not burn out easily. There are two main causes: - Too much current when lit. For that to happen, the series current limiting resistor has to be either very low or plain shorted. Not very likely. - Too much voltage in reverse. All diodes have a maximum reverse voltage beyond which it will blow, and the LED being a diode, it is no exception to the rule. That would be very easy to do if there is no reverse protection diode in series. It might have sustained a nasty voltage spike. Another very improbable (but non-negligible) cause is "infant mortality". Some electronic devices just die early. I have seen a lot of that in my field of work, especially with some types of capacitors. It all depends on how the quality control is at the component factory (most of the time it's just a spot check of a handful of devices, if at all). It's definitely not Atlas' fault.
Thanks for the replies - I appreciate the thoughts. At the moment, I'm going to assume it was an electronic "early death" for the LED, as I can't imagine what I could have done to blow it. That said, it seems strange that it was working up until I did the work on the truck. The good news is that the loco is still running great. I'll get a new LED and see how it goes.
