Larry, Other than that negative voltage supply, the 5 volt regulator, and the 12 volt line, there is just not other places to look for a problem. The MAX1406 just handles two RS-232 signals in this application, TXD and RXD, so there is nothing on the board to stress the chip.
73, Don W3FPR KT4G wrote: > Hello Don, > > Thanks for the insight. I checked D4 and it seemed to be ok. I went ahead > and removed U1 and the voltage on the D1 anode rose from -3.3 to -11.5! U1 > must be bad. The only question is what made it that way? > > I'm going to order a couple of 1406's from Mouser and see if that indeed > fixes the problem. If the original chip suffered from a latent defect (in > other words, was the proverbial "time bomb" waiting to go off), then I > should be ok. If the failure was due to another faulty component then at > least I've got a spare... > > ______________________________________________________________ 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
