On Sep 1, 2012, at 9:02 PM, Don Wilhelm <w3...@embarqmail.com> wrote:
> Bill, > > I am puzzled why a bad EL5146C would cause an INFO 080 problem. INFO 080 > normally is the inability of the MCU to properly communicate with another > firmware processor. While it is entirely possible that the EL5146C was > dragging down the output of the +5v regulator and causing the KPA100 firmware > IC to fault, but I cannot tell from this distance. Don, that was exactly the problem. The EL5146C had shorted internally, and was bringing the 78L05 to current limit at about 1 volt. > As for your wattmeter problems, I suspect that the diodes D16 and D17 may be > "half bad". Yes, that is rare, but possible - they have been damaged enough > to change their characteristics but not make them either open or shorted. > > I would recommend arbitrarily replacing them and then try the wattmeter > calibration again. > For initial settings, adjust R26 to produce 43k ohms to ground as measured at > U5 pin 5, and R27 to give 43k ohms as measured at U5 pin 3. > > After that do the null adjustment and see what happens. I have some 1N5711's on order from Mouser. Can I substitute plain silicon or germanium diodes as a temporary diagnostic tool? 1N914, 1N4148, 1N270, 1N4001, 1N4007 are some that I have on hand. ______________________________________________________________ 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
