Not sure the root cause of the issues, other than the fixes performed.
The core take away from this is that I know the forum has many instances of Overcurrent alarms, and we're all normalized to think inverter failure; But after some initial troubleshooting it *may* just be a issue with the Current Sense/Overcurrent alarm circuit in some of these cases
After following the latest video from Damien on safely starting up the LDU, and my inverter passing all diode tests (and otherwise being in good condition) I went ahead to attempt the first spin.
Upon trying to run, I was immediately greeted with OVERCURRENT and HICUROFS1 errors, with no rotation.
Read the forum posts, which lead me to measure the voltage into U10
Confirmed several of the IC pins had low voltage (~3V) rather than the ~5V expected
After confirming my connector soldering was good, began to probe around the board, Ended up measuring at the associated Vias just upstream from the U10 pins confirming 5V.
Removed board, inspected U10 with definite cold solder joints on pins 1-4. Re-soldered the IC pins (and a few others on the board) and re-installed.
Attempted restart. Overcurrent errors have been resolved, but HICUROFS1 remained.
Graphed il1 & il2, il2 was responding to general noise and initial current, but il1 was flat/zero.
Measured voltage on the Test Points near the lower right of the PCB. Voltage for il1 and il2 was 2.3 & 2.6 volts respectively.
Continued to test the TPs nearer to the center of the board (around IC11) One channel was reading 1.8 V while the other was at 860 mV.
Started probing the board on the bench, having two identical circuits made comparing measurements pretty easy.
Measured 6.9 Mohm across R56, while the il2 partner resistor R49 measured 910 ohm.
Removed R56, measured and confirmed open circuit.
Replaced with a harvested 1Kohm resistor. Not ideal but it did let me spin the motor with minimal impact to the current reading offset.
Successfully rotated the motor (after swapping the encoder A/B wires
)