Damaged by lightning (apparantly), repairable or junk?

[Knight]

Hi!

A couple of months ago some electronics devices in my home were damaged by what appears to be lightning that struck very close to my home (it might even have struck my TV antenna that's on a tower just beside my home).

Are parts that were damaged by lightning usually repairable or should I practice my soldering/desoldering skills with them?

Thanks!

Nick

[willawake]

please be specific on which devices affected

[Knight]

Hi!

Originally Posted by willawake

please be specific on which devices affected

Non-working:

- An old motherboard (Tyan S1854, Pentium 3 866Mhz). It would have been nice if I could have gotten it to work again as I use these old motherboard to make test servers (mail servers, file server, etc...). FYI, caps on this appear to be Rubycon and seems to be ok...

- Network switch (D-Link DSS-8+). It turns on but the status Leds go crazy... If I'm not mistkaen I saw G-Luxon caps in there (a bad brand I believe but they seem to be ok).

- A thermostat that was connected to my electric furnace. The furnace is OK but the thermostat sensor no longer works OK and register a temperature that's too low.

- A network card, looks like something got very shorted because the PC it was in could not be turned on when it was still in it... PC works fine now with another card... This card I dont think it's not worth it to try to repair except maybe to say that it was brought back from the dead...

- The booster than was installed on that antenna... Problem there is that's in two parts and one of these in on top of the antenna and I'm afraid of heights...

Working partially:

- A small tv... It no longer turns off ... In this case I'm not sure I want to play around a CRT...

- The onboard network card of another old PC (Asus P2B-LS, P2-P3 class, I'm not sure which CPU I've got in the currently). The network card is still detected but it no longer works... I think it was based on the Intel 8255x if I'm not mistaken...

I haven't seen any physical damage (blown caps, etc...) on the board themselves...

Thanks and have a nice day!

Nick

[gonzo0815]

Well, if you roughly could estimate where the current and the voltage has benn come from, you can replace all sensitive components on that route and or you can estimate the dammage occured.
Fisrt of all all mosfets and similar silicon devices will probably the first thing which will give up in an overvoltage condition.
So on mainboards there is probably the VRM unit`s mosfets blown, probably shottkys too. It all depends on the absolut value of the overvoltage, but if the lightening was so close, i wouldn´t expect to get anything back working.

[Knight]

Hi!

Originally Posted by gonzo0815

Well, if you roughly could estimate where the current and the voltage has benn come from, you can replace all sensitive components on that route and or you can estimate the dammage occured.
Fisrt of all all mosfets and similar silicon devices will probably the first thing which will give up in an overvoltage condition.
So on mainboards there is probably the VRM unit`s mosfets blown, probably shottkys too.

So it's more or less a loss cause...

I didn't want to mess with them if there was a chance of repairing them but all is not loss, I'll use them to pratice my soldering/desoldering...

It all depends on the absolut value of the overvoltage, but if the lightening was so close,

It was so close that the colors on my TV (CRT) were messed up for a while as if there has been a magnet/magnetic field pretty close to it...

I was very lucky and the TV got back to normal after a few hours (no degaussing needed) I believe my TV has some sort of auto-degaussing when I turn it ON but turning it on then OFF a few minutes after lightning struck didn't correct the problem, only time did...

i wouldn´t expect to get anything back working.

With a lot of luck I guess the only thing that I could hope to get back to full working order is the NIC on the partially working (blown NIC) motherboard... This seemed to have been the only thing that was not as damaged as the rest (except for the NIC, it still works perfectly).

Thank you very much for your help!!

Nick

[Knight]

Originally Posted by Knight

With a lot of luck I guess the only thing that I could hope to get back to full working order is the NIC on the partially working (blown NIC) motherboard... This seemed to have been the only thing that was not as damaged as the rest (except for the NIC, it still works perfectly).

It can you haven't guessed it by now I'm somewhat .... off that the NIC is blown on an otherwise perfectly working motherboard...

Nick

[Rainbow]

Looks like it came through the network. First open the switch. You'll probably see burnt resistors near the ports - don't bother to replace them, the main chip is damaged too. The network card is probably completely fried and it probably took the motherboard chipset too.

[Knight]

Hi!

Originally Posted by Rainbow

Looks like it came through the network.

You came to more or less the same conclusion as I did, the surge got from one device to the other from the network...

The device closest to where lightning probably struck is the non-working motherboard which was connected on the network...

First open the switch. You'll probably see burnt resistors near the ports

They are probably burned/blown but it's not visible (thru-hole and SMT components look ok visually)... I did have one surprise when I remove the switch motherboard from its casing, there's a lot of SMT component on the side which I could not see when it was still in the casing... I'll try to measure the resistance on some of these resistors just for the fun of it, I kinda wonder what I'll get, infinite resistance or none...

don't bother to replace them, the main chip is damaged too.

The way it behaves it doesn't surprise me... BTW, looks like that switch is using a 3 chip chipset (with one "main chip"). My guess is that two of these chips serve 4 ports and then connect to that other "main" chip...

The network card is probably completely fried and it probably took the motherboard chipset too.

I'm am very surprised the other motherboard survived with only a bad NIC, I was actually very lucky in my bad luck...

Thank you very much for your help!!

Nick

[Per Hansson]

They usually put a current limiting resistor, it will be something pretty big, probably blue disc like, see if that is blown to bits... If so desolder it and try again (hoping the lightning will not strike then because then you have no protection)

[Knight]

Hi!

Sorry for the delayed reply...

Originally Posted by Per Hansson

They usually put a current limiting resistor, it will be something pretty big, probably blue disc like, see if that is blown to bits... If so desolder it and try again (hoping the lightning will not strike then because then you have no protection)

I'll take a backup of that pc (if I damage the motherboard I will no longer be able to access one of this pc's hard disks because one of them is LVD) and I'll get the motherboard out of that case...

Sorry for the possibly dumb question but if I remove that resistor do I have to put a wire/jumper in its place?

Thank you very much for your help!!

Nick