Don - Appears problem solved. Pin 4 of the encoder measured "open" to ground.
I messed around for an hour trying to figure out why. I finally found the wire
from the circuit board to the encoder termal #4 broken. I used trimmed
component leads to make the four connections as called out in the book.
Apparently the one on #4 had a nick in it; flexing of the wire during assembly
of the front panel caused it to break. The break was well hidden. I replaced
the wire and encoder functions properly. Ready to move on! Thanks for your
help, 73, Cecil
> Date: Thu, 25 Oct 2012 19:37:16 -0400
> From: w3...@embarqmail.com
> To: cecilsm...@hotmail.com
> CC: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] K2 Alignment and Test Part 1
>
> Cecil,
>
> I suggest you check the soldering on the front panel board, be
> especially aware that on all ICs pin 1 is soldered, that is easy to miss.
> Check the schematic for the front panel board and look at the symbol for
> the encoder. Measure to make certain you have 5 volts on the 5 volt pin
> (measure at the encoder terminal not the board), then turn power off and
> measure the resistance from the encoder ground terminal and ground -
> expect zero volts. {updated to read "ohms" per Don}
>
> Having made those measurements, monitor the voltage at the ENC A
> connection while you *slowly* rotate the encoder shaft. The voltage
> should change from low (about zero volts) to high (about 5 volts) as you
> rotate the shaft. Make the same check for the ENC B signal line.
> If those checks reveal that the voltage is always near zero, the first
> suspect is a damaged input on U3 - that IC is quite sensitive to static
> during the installation process.
>
> I would suggest that the voltage checks on the Front Panel board can be
> misleading if you are not familiar with the K2 - the conditions set up
> prior to measurement must be carefully observed. You are dealing with
> digital signals which are highly dependent on all the conditions being
> the same as on the unit that was measured for the manual list - if any
> condition is different, the results will be different.
>
> 73,
> Don W3FPR
>
> On 10/25/2012 7:05 PM, Cecil Turquette wrote:
> > In process of building an older K2 kit, SN 3943. I'm at the Part 1
> > alignment page 42 - the optical encoder test.
> >
> > Status: All ok to this point with display reading 40M 7100.00c and VFO A
> > However, the indication does not change when turning the VFO knob. I've
> > verified per the steps in Appendix E 012 on page 2, voltages in step 050 on
> > page 3, and all of step 075 on page 5. The 4 mhz osc can be heard in my
> > station receiver and will change when I adjust C22 on the control board.
> >
> > The next test: the relay test appears to work as the band changes and the
> > display reads out for each band. But as with the 40M position, the
> > frequency does not change when turning the VFO knob.
> >
> > Is there anything I should check before beginning the voltage checks
> > beginning on page 15?
> >
>
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