[Elecraft] K2 VFO / Encoder Problem

[Nigel (Nidge) Smith]

Hi Don,

Many thanks for the quick reply.

So far the readings I get on U3 are as
follows:

Pin 14 =  0.1V and 0.133V when the encoder is
rotated.
Pin 15 =  4.12, which varies when the encoder is
rotated.
Pin 7 =  3.4V with slight variation when the
encoder is rotated.

So from the above would you say it's safe to
assume that U3 has a damaged output on
pin 14?

Again thanks very much for taking the time
to reply.

Regards

Nidge (G0NIG)

IO93dv


----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: "Nigel (Nidge) Smith" <nig_smith at o2.co.uk>
Cc: <elecraft at mailman.qth.net>
Sent: Thursday, April 08, 2010 9:17 PM
Subject: Re: [Elecraft] K2 VFO / Encoder Problem


> Nidge,
>
> It is difficult to predice the exact voltage levels that will be present
> in digital signals at any particular time.  That may be why the U3
> redings may be off from what is listed in the manual.  Check by
> comparison instead.
> Compare the voltage at FP U3 pin 14 with the voltage your meter reads at
> pins 7 and 15 - they should be similar.  If they are not, then it is
> likely that U3 has a damaged output at pin 14.
>
> Additionally, check to be certain the signal at encoder pin 2 is making
> it to CB U6 pin 8 and the signal at encoder pin 3 makes it to CB U6 pin 16
>
> 73,
> Don W3FPR
>
> Nigel (Nidge) Smith wrote:
>> I have in my possession a K2 that has developed a fault with
>> the encoder.
>>
>> When trying to tune the radio, rotating the encoder results in just
>> the last digit displayed flickering back and forth.
>>
>> At first I thought the Optical encoder had failed and so ordered a
>> replacement from Elecraft which arrived yesterday.  Today I installed
>> the new Encoder only to find that the problem still persists.
>>
>> I have checked and confirmed there is a 5Volt supply on pin1 of the
>> encoder, pins 2 and 3 fluctuate between 5Volt and 0.1Volt when the
>> encoder is advanced or retarded. Pin 4 appears to remain at 0.1Volt.
>> In the voltage charts at the back of the manual Pin 4 is connected to
>> pin 14 of U3, this according to the charts should be about 3.1Volt.
>>
>>


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