This is what’s known as a Master 4 module in a LHM550 Liebherr harbour crane.
Earlier this week it was hit by lightning causing the module to output a combined 8 volts out on the can line 3 circuit.
The rest of the module works fine, all functions work except anything related to can line 3.
Can line 3 output is the 2nd white plug port on the top left of the photo.
I know it’s probably a long shot but does anyone have any familiarity with these kinds of things?
I have added a couple more photos in the comments.
I couldn’t visually see any sort of obvious fail point.
Judging by the location of the PWR plug and general layout, plus the large tantalum caps next to the inductors I think that’s a bank of DC switching supplies. Signal inductors I would expect to be closer to the size of L25-L29 shown in that photo.
The rest of this is good advice though! It’s CANbus so there should be a set of optocouplers somewhere to protect everything from, an admittedly less significant, type of ESD event. However, I’m not seeing anything I can immediately identify as one. Are there components on the underside as well?
The optocouplers themselves might be okay, the things most likely to be killed are diodes and capacitors. A fixed 8V would make me suspect one of those failed as a short. If you have a thermal cam handy and value your time over potentially damage you can short the signal to ground and use the cam to try and identify what specifically is damaged as those should heat up significantly when directly shorted to ground1.
^1 use a loose wire, shorting events should be kept as short as possible, increasing the duration after each sweep with the cam. Don’t do this with the power line. If the circuit was undamaged this should be fine for the signal lines, but poor/cheap design + damaged circuit could cause any amount of havoc. Do at your own risk, etc.^