[Elecraft] K2 Encoder problems continue.

[Don Wilhelm]

Nidge,

That means your problem is indeed confined to the display.

It is entirely possible that you have a bad output from the MCU (CB U6) 
at pin 14.  The most certain confirmation of that would be to replace it 
with another firmware chip.  Yes, with a 'scope, that fact could be 
either confirmed or denied, but without that validation, my next best 
guess is for a bad output from the MCU at pin 14.

If there is another K2 owner in your area who would allow you to swap 
Control Boards from their known working K2, that would confirm that the 
MCU chip is the most likely problem source, but lacking that 
possibility, the best recourse I can see is to obtain a replacement 
firmware chip from Elecraft and try that.  The bottom line is that 
digital circuit problems are difficult to analyze without a dual trace 
triggered 'scope and some knowledge of the initiating events (to 
determine when to trigger the 'scope).

73,
Don W3FPR

Nidge (Nigel Smith) wrote:
> Hi Don and Geoff
>
> Thanks for the replies both.
>
> First of all Geoff: I'm afraid I don't have a scope here anymore.  I did
> remove the MCU
> and checked the voltages, and this time on pin 14 of U3 I had the correct
> voltage close
> to 3.8V, with the MCU inserted it was below 100mV.
>
> Don:  I've checked the the readings at TP1, when spinning the encoder the
> frequency
> does not change.  At TP3 the frequency is close to 12,100KHz with Band +
> and close to 12,085KHz with Band - .
>
> I've also checked the 4MHz oscillator and this is spot on.
>
> The radio, when connected to Hamradio Deluxe works fine under computer
> control, both
> on receive and transmit.  The filters are off but that's because I'm unable
> to fine tune them
> as the encoder isn't working.
>
> Any more thoughts on the matter greatfully received.
>
> Regards
>
> Nidge (G0NIG)
>
>   
>