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.
I have had a lot of experience with things like this and I know you don’t want to hear it and it’s a bummer, but lightning damage is always fatal. It damages so many parts, it becomes a game of whac-a-mole. And even if you replace enough components that it starts working again, it won’t ever work right. Lightning damages components in ways where it sort of seems to work, but then it misbehaves in strange ways. Either the thing is very easily repairable because it was protected by something designed to fail and be easily replaced, or it’s a lost cause. This seems like the lost cause kind of situation, I would suggest replacing the entire unit.
Yeah already done that and a second module at a cost of 17k for the two.
Was just an exercise in curiosity really since they get hit once or twice a year
Does Liebherr not support this model anymore? For something like controlling a harbor crane where failure could be deadly I would think they should be the first point of contact and they should probably just be going ahead and sending a replacement part. Lightning can do weird damage to electronics even without a direct hit, so even if you find and fix a more obvious problem something else could be lurking that bites you later. When that’s controlling something that moves tons of cargo through the air I would think the safest course is to just replace the damaged part.
Replaced already was just an exercise in curiosity.
Liebherr don’t repair them they just sell a new part.
(I used to work for them before going independent)
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
Do the buses really need to be separate? Because what I’d do in this case is to join two buses into one so that you can live without that one port. CAN bus can be connected in parallell, just be sure to modify/relocate the line terminators so you get the right amount of resistance on the data pair. Should be 60 Ohms, iirc. Measure one of the working lines to be sure.
Lightning strikes are a PITA to fix. I spent so many hours troubleshooting this radio installation on a ship and once one component was fixed, another broken one was discovered. In the end we just replaced the entire thing.
Unfortunately they need to be separated due to the logic and control system.
Can line 3 is independent of the rest of the machine to allow recovery when it fails.
If it’s linked with the rest ordinarily and something like this happens then it would be dead with no simple way to recover it
You’re not wrong about lightning though as a crane technician i see lightning strikes far to often and it’s always expensive and time consuming
Do you have a schematic for it? That could help pinpoint where a failure causing those symptoms could be. You may also be able to measure the voltages going back from that plug and see where the issue is occurring. But a schematic would be very helpful there too!
I wish we had a schematic.
Even when I worked for Liebherr once a circuit entered a control module it may as well be a magic box Liebherr are very protective of that information.
