I just had a 270V fault come up on the KPA500. It's sorted now (I hope!) but I'm a little confused as to how it happened, although I do have a theory.
I was fiddling around the back of the amplifier trying to retrieve a mains multiblock which had fallen off its usual perch. The amplifier was on OPER. Suddenly there was a buzzing and the FAULT light lit, along with the 270V warning. I was able to halt the buzzing by switching back to STBY. However, when I went to switch off the amplifier with the ON button on the front, the amplifier went into hard fault mode again and my only option was to use the main switch on the back. However, when I switched back on again, effectively cycling the mains power (manual page 13, just to prove I have RTFM), I still had the 270V fault upon returning to OPER mode. Once again, the only way out was turn off at the back. At that point my wife called me for supper. When I returned, I decided to remove the top cover just to check the safety interlock - all was well and still intact, the microswitch making a reassuring click. Put the top cover back on, fired up the amp again and all is well. Is it because when the amplifier is switched off from the back without first turning off at the front, the capacitors remain charged and the KPA500 is not seeing a mains power on/off/on cycle? Perhaps these capacitors discharged sufficiently during supper for the power cycle to reset the KPA500? I'm just grateful it's still working :-) Thought I would share in case anyone else hits the same problem. I can only imagine that I momentarily knocked the IEC main plug in the back of the KPA500 when I was fiddling around. Should have switched it off first! 73, Stephen G4SJP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
