[Elecraft] K2 Conrol Board Resistance Checks

[harry17b]

Hi

I have not long been building K2 #2378, and have just reached the
resistance checks, for the control board, on page 20 of the manual.
Using a digital meter I find that I get different readings according to
which way round the leads are connected. I presume that this is due to
polarising some of the semiconductor junctions in the path measured.
Taking the best of the two readings, most checks are ok, but I get
rather low readings for U6 Osc 1 and Osc2   -- 88 or 42k and all U8
tests -- 85 or 42k;  these are instead of the > 100k quoted. Should I
be worried about all this?

Since typing that I prised out the controller MCU (with great
trepidation in
case I snapped it!!!) and found that Osc1 and 2 now read infinity, so
it's
leakage through the IC itself. I have taken great care to NOT TOUCH the
pins -- I use plastic tweeezers to handle ICs and a proper tool to
straighten
the pins. I have also checked very carefully  for solder bridges etc, so
I'm
convinced it's not a soldering problem.

It seems to me that the sense of the resistance meter leads could be
important in polarising the electrolytic capacitor on the 8v and 12v
lines? The normal way, connecting the meter's 'negative' lead to ground,

puts this at a higher positive potential than the 'positive' lead when
used to measure resistance, at leads it does with my analogue meter.

Any help would be greatly appreciated.

73

Hugh M1ETU