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.
Full disclosure, I’m not an expert on this equipment, but some insight I can provide might be better than nothing if you get no other answer posts.
I don’t know this hardware, but interfaces very often have some kind of buffer circuitry right before the connector that leaves the unit that doesn’t change the logical signals but provides either circuit protection to the model or signal stabilization. If you’re not getting any variable signal (and just getting that standing 8v out) then this is where I’d look first.
If I deciphered you “2nd white plug port” then its this photo, and the circuitry I’m talking about I’ve circled in blue:
This looks like what I’d expect to see. The larger black cubes are inductors (coils). I can’t see the number to know what those 8 pin SMT ICs are next to each inductor, but there’s an orange capacitor and series of smaller inductors next to each. This feels like signal buffering stuff. If your surge came in through that connector, then this would be the part of the board damaged and where I’d start the search. The good news is, that buffering logic is pretty simple. It doesn’t “create” it likely just “stabilizes” or “cleans up” what the rest of the module creates.
As a technician, I’d get the pinouts of those 8 pin ICs, identified the input to each, and put my oscilloscope leads on those input pins. If you’re seeing good signals (not a standing 8v signal) then you know the rest of the upstream logic is good, and you just have to replace some cheap front end buffering components.
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.^
Cheers that is where the output is you’re great at deciphering my ramblings haha.
We’ve already gotten the machine running with a new board but out of our own curiosity we wanted to see if there was some sort of “simple” fix.
I might give this a try and go from there