K2 VFO / Encoder Problem

Posted by Nidge_(G0NIG) on Apr 08, 2010; 7:22pm
URL: http://elecraft.85.s1.nabble.com/K2-VFO-Encoder-Problem-tp4873251.html

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.

Obviously the encoder is not at fault, unless I've been un-lucky
enough to have received another duff one.

Any advise on where I should be looking now.  Could it be possible
that U3 has failed as some of the pin voltages for this IC do
not correspond to those listed at the back of the manual.

Many Thanks in Advance.

Nidge (G0NIG)

IO93dv
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