For the third time in 14 months, my cable modem quit working. The first two were SB6183s, the last was a MB7420 that says “enhanced surge protection” on the box.
All 3 times, the modem is just crowbarred - no lights, no nothing. I have tried cutting the wires and powering it with a lab supply, the failure isn’t the wall wart. (also have tried wall warts from replacement modems that I know work)
The first hit and the third hit, I also blew up my router, which is a Google Wifi pod. Same symptoms - no lights, a known good wall wart will not revive it. The second hit, I ran the ethernet line to the router through an APC UPS. But after the modem blew out, I noticed internet speeds were slow (I guess I blew some of the surge protection pairs in the UPS) and connected the router directly.
And nothing on a surge protector was damaged the first hit, and the second 2 nothing else was broken anywhere in my place.
So it must be surges coming in through the cable coax. It always happens when it’s stormy and cloudy outside. Two separate apartments within a mile of each other.
I’ve rebought my equipment and also picked up a dedicated coax protector and a dedicated gigabit ethernet protector. What else can I try? Anyone else have this happen?
Had it happen once, ten or twelve years ago. After a storm the (home) office stank of burnt plastic - wifi router dead, computer dead. There had been a lightning strike on a local electricity substation, and the surge just burned out computer stuff (and nothing else) for some reason. You’re the first person I’m aware of who had the same issue (oddly, I wasn’t aware of neighbours having problems). I took the hit, bought new kit and carried on. My reasoning was - this is so rare it simply isn’t worth getting into protecting against it.
There’s a couple of things that may be contributing factors; If the co-ax is carrying DC like it does for the LNBFs for satellite TV and your filters on the equipment fail; or excess current was induced by solar activity, lightning or some other man made cause. It could also just be bad grounding on your AC wall plugs. I lived in an older house at one time and none of the plugs were grounded until I complained. As it was I lost an alarm clock and a router before it was addressed.
I am not an engineer, but I’ve heard that surge protectors are a finite resource. Every time they protect your equipment from a surge, they take some damage and become weaker. Eventually they absorb enough damage that they no longer work as protection. So you need to periodically replace your worn out surge protector with a new fresh one.
I used to be a life safety engineer. Whenever we had to use datacom equipment With a life safety system we would put lightning arrestors on the line right as it came into the building in a convenient place. The lightning will take out those as a sacrificial lamb instead of the equipment that rides down the line. You can get them from any sort of equipment supply house that sells that kind stuff. They’re not too expensive but they are life safety rated so they’ll actually work. Try a place like Tri-Ed or SDI.
Old anecdotal story, we used to test the grounds of the building by going and taking a whiz on the ground rod outside. If the resistance to ground drops whenever hit that warm salty water hits it then you need a deeper ground rod
A few years ago, a lightning strike caused a modem, two TVs and a Roku box to fry. My wifi router was left unscathed, however. After much back and forth, Comcast finally admitted that they had failed to ground their lines properly, and they reimbursed us for the lot and, presumably, fixed the issue.
Don’t forget that there’s a limit to how much any surge suppressors or other protection can do. The lightning has already jumped through miles of empty air; if you get too close a strike, there’s nothing you can put in the line that’s going to stop it. With a really close strike, it’s even possible for the pulse to damage equipment that’s completely unplugged.
That said, proper grounding and suppressors certainly help keep damage from indirect strikes to a minimum.
Update. Well I didn’t do any troubleshooting because I had the same symptoms as the last failure. Turns out this time my equipment was fine. The cat had stepped on the power button on the UPS. Found this out when plugging in the replacement modem and noticing it wasn’t coming on either.
