So we get a new-manufacture, new-layout circuit board
with nominally the exact same behavior and topology.
turns out, after two days of debug, that the board I have
has a bad relay. I was wondering why the calib routine
didn't work. Spent at least a day with the VP of engineering
debugging; he kept saying, lets try it on the test fixture.
All the new boards were good; but mine had a bad relay, which
had escaped the ATP for the boards.
Classic. I had to debug by realizing I was seeing open
circuit resistance (shows as 1800 ohms) when I should have
seen 100.0. I was at one point seeing the resistance of the
attached external resistor. That revealed a bug where the
receptacle for the external resistor was switched in.
But with that fixed, I still saw open. Intead of 100.
Eventually i convinced myself it was open, instead of 100,
and the analog guys found a bad relay (one of 25).
