Hi Don, OK, on that line which is pin 14 on U3, there is only a couple mv but no pulses. The state of that line never changes. The other strange thing is the ENC-A data level only being 2v p-p verses ENC-B which is a full 5v p-p signal. Shouldn't both ENC data lines be a full 5v p-p TTL signal?
Worst case, does Elecraft take in repairs direct? I could send in both display boards if that is the case. I sure wish I had test boards to swap in, to verify which board is causing the issues. I received the final amp rebuilding components the other day but I will wait to install them until after this dead VFO issue is repaired. Mike WE0H Don Wilhelm wrote: > Mike, > > Other than the wiring paths for ENC A and ENC B signals through the > connectors and to CB U6 pins 8 and 16, > there is nothing else for these two signals. However, for the encoder > to be read, the /ENC RD signal must be at a low level and that signal > is generated from FP U3 pin 14. Look for low going pulses with your > scope. If they are not present, FP U3 may be at fault. > > 73, > Don W3FPR > > > Mike-WE0H wrote: >> Hi Don, >> >> Ref K2 #6698: >> >> I tried a new encoder but it did nothing different than the original >> encoder. Tonight I see that ENC-A is only 2v p-p while ENC-B is 5v >> p-p. This is measured right on the encoder terminals and on the U6 >> MCU chip. I don't see any resistor network pull ups on these lines. >> Do you think the MCU could have gotten hurt with the spike on the 14v >> VCC line that shorted the one final and that VCC filter cap? I see >> data on both ENC lines when I spin the encoder. The Encoder VCC is a >> solid 5.0vdc. All other functions work on this radio except anything >> where I need to turn the encoder to access something in a menu or >> change anything. The radio receives fine on whatever the display freq >> is and transmits fine on the same freq on all bands. I just can't >> change any VFO digit other than the far right digit, or if I spin the >> encoder shaft left & right, it will slowly increase the displayed >> freq but not go down. >> >> Mike >> WE0H ______________________________________________________________ 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
