>  king into: 2.7k for the former; 22k for the latter.  Does anyone
> have any ideas about what might be causing the op amp to latch up?

Nope... But, if you suspect the switcher why don't you temporarily use a
linear supply to power the *new* board and see if the latchup problem goes
away. Maybe the problem is somehow layout related?

Gerhards idea of simulating the lower impedance by adding a 3K seems like a
good thing to try as well.

-- Mark



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