Hello Lewis, I experienced this same issue once, and the problem ended up being the Transil diode D28 on the main pc board, near the 12 vdc power input connection. It is a large diode, and I believe it's purpose in life is to protect against excessive input voltage. It should begin to draw current when the voltage goes too high, and that should blow the resettable fuse F1. In my case, I was running the power supply voltage at about 15.0 vdc, and I suspect that my particular diode may have had a slightly lower threshold than normal, and was probably drawing current and dissipating power, though not enough to blow the F1 fuse -- until it failed completely by short circuiting. (This is just a guess; The replacement that I received from Elecraft has been working fine though.)
If you can, try measuring the resistance in both directions across diode D28. To really prove it though, you'd need to lift at least one end of that diode and then measure it. Spec sheet on the diode: < http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000695.pdf > Best of luck with your troubleshooting. 73, Dale WA8SRA On 10/19/2012 2:50 AM, Lewis Phelps wrote: > Yikes! My reliable K3-10 has developed a short circuit across the power > input terminals. Well, to be exact, not quite a dead short. It measures 0.6 > ohms across the PowerPole connectors. It most certainly does blow fuses on > the input line. > > Any suggestions for trouble shooting? And also for a possible cause of the > problem? > > Lew N6LEW > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
