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Hi, I am a total novice and have a train that we bring out every year at Christmas. Well I hooked it all up last night and the throttle control on the power unit did not work (the train started going slowly and never stopped) and when I switched directions, the overload light on the unit would go on.
The transformer is an Athearn Model SDK-789.
Do I need to replace the transformer?
Thanks in advance!
sounds like a short somewhere.
How is the track set up? Just a simple loop? Or a loop that reverses back on itself?
It s a simple loop. Big oval. Anyway to test the transformer to see if it is working?
Do you have a volt-ohm meter available? If so, test across the variable terminals of the transformer as you slowly advance the speed control. The voltage should rise evenly from 0 to about 14 volts at full throttle. If you don't see that happening, there's a problem with the transformer and it needs to be replaced.
Another test you can try is just lay out three or four sections of straight track and hook up the transformer. If the engine runs OK then, you may have a rail joiner that's causing a short. Pull off all the rail joiners and replace them, making sure that they are tight and even at each joint. It may also help if you clean all the track. A pencil eraser will remove most of the heavy corrosion ad cleaning the rails with a rag dipped in rubbing alcohol should clean up the rest of it.
Thank you very much. I have a volt/ohm meter and will test the output tonight. I also will clean the rails.
John
I have found the problem. There was a small short that was causing all of the issues. A tiny wire shorting from the DC to AC.
Thanks All!
Ah, the joys of stranded wire...
That's one advantage of putting a meter to it - it forces you to take close look at the wires.
I'm glad it turned out to be something trivial...but I'd still give the tracks a cleaning.
Will do over the weekend. I installed u shapped ends on the bare wires so no more shorts.
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