Thread: Lightning and my motherboard...

Originally Posted by Perry Cox

My house was struck by lightning a few days ago. Some of our electronics are fried and some of them are fine. I think the surge came through the cable because our modem, TV, router, and a few other things that were connected to router/TV are toast. ...
Has anybody salvaged a lightning-surged computer before?

We literally replaced semiconductors to eliminate lightning damage. To also learn how surges did that damage.

Your assumption is wrong. If cable is properly installed, then it already has the best protection possible. First understand how surges (electricity) works. It does not come in one wire, do damage, and stop. Electricity means current is incoming on one wire. And same current is simultaneously outgoing on some other wire. If that incoming and outgoing path does not exist, then no damage.

A ligthning strike far down the street to AC wires is a direct (incoming) strike to every appliance (powered off or on). Was every appliance damage? Of course not. Only some appliances also had that outgoing path to earth.

Cable already has best protection possible - a direct wire connection to earth. What appliances were damaged? Only ones with an outgoing path - ie via cable.

Averting a surge means energy must connect to earth BEFORE entering the building. Once inside, nothing can avert that surge. Many plug-in protectors are so grossly undersized as to fail even on surges that cannot harm many appliances. Effective protectors costs about $1 per proteted appliance. Earths direct lightning strikes. And must not fail. Only grossly undersized protectors fail after a lightning strike.

So, how to fix a surge damaged appliance: Often damaged is something on the outgoing path. In most cases, only one part in the surge path fails (long after the current was incoming and outgoing). What is not damaged? Incoming current was to RAM, CPU, and disk. But no outgoing path existed. So those parts would not be damage. Outgoing path is via the NIC port to cable. Damage may (or may not) be there.

Find damage by tracing potential paths from AC mains to cable. If a surge current passes through motherboard and NIC, then it was probably passing through a router and cable modem. Are those parts damaged? Maybe. Due to superior protection, a surge can go through those devices on paths intentionally designed to result in no damage.

I have salvaged many surge damaged electronics. Some of the easiest were 56K modems. In fact, one 56K modem destroyed by lightning is still contacting Fax machines today as if never damaged. Solutions always begin by first identifying both incoming and outgoing surge paths.

The most common damage is incoming on AC mains (because a homeowner did not earth a 'whole house' protector). Outgoing via cable and telephone appliances. Because those lines had surge protection (installed for free) longer than you or I have even existed.

That's a pretty good detailed explanation.

You should test all your computer components individually if possible. Anything or everything could potentially be damaged.