http://elecraft.85.s1.nabble.com/Re-K2-trouble-shooting-tp3943308p3945274.html
variation. Yes, the levels must be above or below the switching thresholds.
Elecraft does repairs, but only on complete kits. If this is the route
> 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
>>>
>
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