[Elecraft] K2 Faulty menu switch?

[Gerald Wolczanski]

I seem to have fixed the problem - the K2 ran for 11 hours yesterday
without a hiccup.  I've got it running on the downstairs workbench this
morning and, if nothing is amiss, I'll button it up tomorrow morning.

Here's what I did, sorta in the right order:
1)  Snipped the protruding wires on the rear of the encoder board.
2)  Re-soldered U2.
3)  Put plastic between the control board and the encoder board.
4)  Re-soldered RP1 pins.
problems persisted.
5)  touched up (re-soldered pads) around the damaged area.
6)  Did resistance checks on all the damaged traces.  While they
    looked a little scruffy, all was well.
7)  Re-soldered all the pads on the multi-pin (18?) connector.  Note
    that the U2 pull-up resistors are not on the same board as U2.
8)  Gave both the control board and the front panel board a thorough
    inspection.  I did touch up a few solder joints here and there -
    probably not necessary.
9)  So it's back together at the moment, minus the front panel 
    which I'll install tomorrow.

Built this radio in early 2015 and aside from blowing a pair of finals
(testing antenna couplers) it has performed flawlessly.  Oh yeah, I
now use a resistive bridge when tuning the open-wire feed!

Huge thanks to Don Wilhem for setting me on the right trouble-
shooting path.  And big time kudos to Eric and Wayne for such an
amazing design ("look ma, no cables!").

Thanks
Jerry W
KI4IO
Warrenton VA










On Sun, 2022-10-23 at 11:35 -0400, Don Wilhelm wrote:
> Jerry,
> 
> Yes I see the photo.
> 
> Although it looks like the copper is intact, I would scrape away a
> bit 
> of the silkscreen on each end of the damaged area and then solder a 
> small gauge wire across the damage.  If you have some #24 wire (from 
> ethernet cable for instance) use that rather then the #22 wire
> supplied 
> with the K2 kit.
> It is usually best to route the wire along the original PC board
> trace 
> so you can tack it in place at several places along the way from end
> to end.
> 
> Reflow the solder on the encoder board just in case that is the
> problem.
> 
> 73,
> Don W3FPR
> 
> On 10/22/2022 9:33 PM, Gerald Wolczanski wrote:
> > Don, indeed it was the FP encoder board touching the back of the
> > control board.  I'm attaching a photo, which I guess only Don can
> > see.
> > The PCB traces are dinged up, exactly .3" apart.  Two things:
> > 
> > 1)  Wonder if the control board or the encoder board may have been
> > been
> > damaged by these boards touching?  Occasionally, in these last few
> > days, the encoder freezes up and a tap on the menu switch gets it
> > back
> > to normal.  Even after I trimmed the encoder board leads and put a
> > piece of think plastic material between the control board and the
> > encoder board, I still get the occasional encoder freeze-up.
> > 2)  Can I try and flow some solder on those damaged traces?
> > 
> > Thanks so much for your help!
> > 
> > Jerry
> > KI4IO
> > Warrenton, VA
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > On Sat, 2022-10-15 at 17:36 -0400, Don Wilhelm wrote:
> > > Jerry,
> > > 
> > > That does sound like it might be a bad solder connection.
> > > Try resoldering Front Panel RP1 and U2.  Those components are
> > > critical
> > > to decoding the switch matrix.
> > > You might also try reseating Control Board U6 - but do so in a
> > > static
> > > controlled manner.
> > > 
> > > With that 7xxx serial number, you might instead have a problem
> > > with
> > > the
> > > FP Encoder board contacting the back of the Control Board which
> > > causes
> > > "strange things" to happen.
> > > Flush cut all leads on the encoder board (right through the
> > > solder
> > > fillet) and also on the Control Board where the encoder board
> > > could
> > > contact.
> > > As an extra measure, put an insulator (fish paper is best, but a
> > > piece
> > > of card stock or better yet, a piece of flat plastic (like from
> > > many
> > > forms of plastic packaging) between the encoder and the control
> > > board.
> > > 
> > > 73,
> > > Don W3FPR
> > > 
> > > On 10/12/2022 5:51 PM, Gerald Wolczanski wrote:
> > > > from KI4io - Jerry Wolczanski
> > > > 
> > > > My K2 started exhibiting this problem in June and it's gotten
> > > > worse.
> > > > The LCD toggles rapidly between the frequency and the last menu
> > > > used.
> > > > A tap on the menu switch restores the display to normal.  It
> > > > was
> > > > quite
> > > > infrequent to start, but now it's bothersome, happening every
> > > > 10 -
> > > > 15
> > > > minutes.
> > > > 
> > > > I re-flowed the switch contacts on the front-panel board this
> > > > morning,
> > > > but the problem persists.
> > > > 
> > > > Is this a switch issue or something else?
> > > > 
> > > > K2 S/N 7xxx
> > > > 
> > > > KI4IO
> > > > Jerry Wolczanski
> > > > Warrenton, VA
> > > > 
>