Fixing BAK Electronics IMP-2 Electrode Impedance Tester

BAK IMP-2 Tests a 1MOhm Resistor, declares impedance to be 1MOhm. 

In getting ready to do some electrophysiology I fixed up a broken a BAK IMP-2 Electrode Impedance Tester.  This unit measures impedance at 1kHz.  The device I got was given to us free in a broken state.  My guess was that some op amps got fried by a "naughty" experimenter.  This was indeed the case, however, not one, but two op amps were destroyed.  The unit runs off of two LF442CN dual op amps and one OPA111A high precision op amp.  The burned out components were the OPA111A and one of the LF442CNs.  Lucky for me, we found replacements for both components the same evening and the unit is now as good as new!  I must thank my awesome tech for helping me verify the broken op amps and find replacements! Ready for electrodes.