[Elecraft] K2 VFO Freq Display Stuck (again)

[Don Wilhelm]

Casey,

To be safe, make one check before proceeding with anything else - check 
the 8T signal line to be certain it is at a low voltage (CB Q1 Collector 
or RF board D7 anode).  If it is near zero volts all is OK there, but if 
it is near 8 volts, then that must be corrected before investigating 
anything else.

OK, I am going to assume that 8T is near zero volts --- (if not true, 
ignore what follows and get back to us).
It would appear that the /ENC RD signal line is being pulled low at all 
times - it would be nice to observe it with a 'scope to see how 
frequently that signal is low.
You can check the encoder by reading the voltage on the ENC A and ENC B 
signal lines to the microprocessor.  As you slowly turn the encoder 
shaft, they should vary from a high level to a low level.  If that 
happens, the encoder is likely OK.

I would suggest you record all your menu settings (the K2 A to B 
Instructions have a nice chart for that) and then do a Master Reset - 
re-enter all the menu entries afterwards and see if the problem goes 
away.  If the Master Reset did not correct it, Front Panel U3 may be faulty.

73,
Don W3FPR

On 12/29/2011 4:27 PM, TI2/NA7U wrote:
> Back in April I had a problem with the frequency not moving (just final digit
> flickering) and that turned out to be a broken wire to the encoder. Again
> the problem has cropped up with identical outward symptoms. I checked the
> encoder wires again, all are fine.
>
> Here are some measurements that were asked for last time. The voltage
> measurements shown are only ones that differ significantly from those listed
> on pg. 16 of the K2 manual, Appendix E. The manual reference voltage is in
> parentheses.
>
> U3: pin3 4.8 (0.8), pin 7 3.5 (2.0), pin 13 4.7 (0.2), pin 14 .1 (3.1), pin
> 15 4.1 (0.8), pin 18 .08 (3.6). The manual notes that all the voltages on
> these pins may vary.
>
> Resistance measured at each encoder pin with the FP board removed:
> Pin 1 24K, Pin 2 106K, Pin3 106K, Pin 4 29K
>
> Can someone help me troubleshoot this? How do I tell if the encoder itself
> is bad?
>
> vy 73,
>
> Casey, TI2/NA7U
>
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