Thank you Don. Confirmed I have 7.8V at anode of D6 and zero at anode of D7 in RX.
U3 is a TPIC6B595N which is in stock at the usual online electronics retailers and very inexpensive. 73, -Josh WU7H On Thu, May 27, 2021 at 1:33 PM Don Wilhelm <[email protected]> wrote: > Josh, > > Your investigation is "spot on" and I would normally recommend replacing > Front Panel U3. It is possible for it to have one bad input and is > quite static sensitive. > > But first, check that 8R and 8T signal lines are working properly. An > easy place to check is at the anodes of RF Board D6 and D7. > The anode of D6 should be near 8 volts during receive and the anode of > D7 should be close to zero. > That situation will reverse during transmit. > > If you find 8R and 8T are on at the same time, that could be reason for > the problem. > If you have a problem with those signal lines, check back on the control > board at Q1, Q2, Q3 and Q4 to determine where the problem might be. > > 73, > Don W3FPR > > On 5/27/2021 4:15 PM, Josh Gibbs wrote: > > My K2 (SN: 4073) suffered a sudden problem yesterday. I didn't notice > > anything happening - one minute it was working normally and the next the > > VFO knob stopped working. > > > > All other functions appear to be working normally, but the rotary encoder > > is disabled. > > > > If I ground the V- pin (via 100 ohm resistor) the encoder comes to life > and > > functions normally. > > > > I have verified good continuity between encoder V- and pin 14 of U3. > > > > In the manual it says that the MCU can disable the encoder under certain > > operating conditions. What might those conditions be? One thought I have > is > > that the MCU is disabling it for some reason. > > > > My current plan is to try replacing U3. All other functions of U3 appear > to > > be working. > > > > Any troubleshooting advice would be appreciated. Thanks for reading. > > > > > > ______________________________________________________________ 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 Message delivered to [email protected]
