Zeus is a real SoB sometimes

[Brenton Piercy]

Merry Christmas you all. Wanted to do a little post to log down some fun and unexpected work I've been doing on Perla since November. She's been down in Mazatlan since last November and we had planned a trip last month to do the Bash and bring her home to SF. Unfortunately when we were going through our system checks we discovered that quite a few bits of electronics had stopped functioning. 

It all started when testing the lights, first the stern light wasn't working. Then we noticed that the deck lights on the spreaders were tripping their breakers and the the steaming light wasn't working. Oddly the masthead tri-color was working just fine. We didn't think too much of it and just chalked it up to corrosion or some bird related damage. 

Then the next day I flipped on the chartplotter and simnet. The chartplotter powered up but couldn't see data from any sensor. Depth, speed, gps, autopilot, radar, fuel tanks, water tanks, AIS, you name it, it was gone. In hopes that it was just the chartplotter I took my handy dandy Raspberry Pi4 computer that I'd built up as a secondary chartplotter at the nav station and connected it to each sensor individually to see if it functioned starting at the top of the mast and working my way aft. 

Anemometer - check (weird)

Fluxgate compass - check (phew)

Depth - dead

Speed through water - Dead

Port Water tank - Dead

Starboard Water tank - Dead

On to the aft section of the network. I connected a spare water tank sending unit connected to the forward part of the network to make sure the wiring from mast aft worked. It looked just fine. 

Then the aft components themselves. 

Port and Starboard Diesel tanks - Dead

AIS - Dead

GPS - Dead

Radar - Dead

Autopilot Computer - Dead

Wind Instrument - Dead

Depth Instrument - Dead

Autopilot Controller - Dead

Chart Plotter - Dead

FFS! Even the FM radio is toast. 

Well, here we were in Mazatlan with zero instrumentation. I decided since the GPS, depth, and autopilot were toast that we were abandoning the trip until I can sort out a fix. I called all the crew that were to meet me along the way and told them the plan, packed up a bunch of the components, and headed back to the shop to see what could be done. 

[Jeffrey Wheeler]

Sounds like a lightning strike

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[Brenton Piercy]

Once I had everything back stateside I whipped out the drivers, volt meters, and oscilloscopes and got to work. I started with the AIS transceiver and the AIS/VHF splitter as I figured that was the front of the line when it comes to the tallest point on the mast. Sure enough lots of magic smoke had been let out of those poor little ICs. 

That's the inside of the NSPL-500 which switches between the VHF and AIS so I can use the same antenna on top of the mast. I think we know now where the pixies got into the boat from. I figured this part is sort of a write off as it's not insanely expensive and I can do without is as I've actually got a second antenna on the stern that the AIS was using before. I'd JUST INSTALLED this before leaving for storm season. *sigh. Just lucky I reckon that this was now connected to such an easy path for lightning to make it through all the networked electronics. 

For the rest of the critical components I decided to do some ebay shopping and try my luck there. I found a used NSS12evo to replace the NSE12 I had which I was pretty happy about. It arrived and I set it up on the bench. Works great. The autopilot controller needed to be replaced so I went with a new AP44 to stick with the SIMRAD hardware. For the autopilot computer I looked around and then decided to try my had at repairing the computer. From looking at the circuit board there wasn't anything visibly wrong. I probed the power, ground, rudder sensor (RF300), and then the SIMNET connector. In my experience the CANbus transceivers for these networks are super sensitive. Usually some TVS diode dies and they're super easy to replace. For this one it was actually the transceiver that died. Here's the CANbus signals from the network when the AC42 isn't connected. Nice clean signals. 

Then when I connect the AC42 it looks like this right at the connector. Explains why it was bricking the network. 

So now we need a new transceiver chip. Here's what this process looked like. 

https://youtube.com/shorts/Iw4gifV9sK0?feature=share