[Elecraft] K2 rotary encoder

[Josh Gibbs]

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.

73,

-Josh WU7H