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Ethernet port not working after power outage

By HaLo2FrEeEk
Jul 3, 2011
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  1. My area experienced a power outage last night during a thunderstorm. My computer is plugged into a surge protector, but my modem is not, and I'm using a wired connection. When I got home from work, I discovered that not only did the power outage knock out my internet service (something on the ISP side) but it also did something to my ethernet port.

    I can see the device in the BIOS, and in the Device Manager, and also in Network Connections, but no matter what I plug into it, it just says "network cable unplugged". I definitely have a cable plugged into it and into my modem (which is on and working, just not connecting to the internet), and I know that the cable is fine (I tested it for continuity, and I tried a different cable). When I plug something in, the lights that normally indicate activity (or at least the existence of a cable) don't light up, so I'm a little worried.

    I realize that a surge from the power coming back on might very well have fried the circuitry, but I'm confused because (knock on wood) nothing else appears to be damaged in my computer, and the modem itself appears perfectly fine (with the exception that it won't connect to the internet which, like I said, is due to a problem with AT&T's lines). Is there some diagnostic that I can run or something I can do to verify the integrity of the ethernet port? If I look at the motherboard itself, would it be possible to see any potential damage?

    I would think that if the circuit was fried, it wouldn't show up at all, but it's there, it even has the name and everything. It's an onboard "NVIDIA nForce Networking Controller", and I'm running Windows 7 x64.

    I can't afford to buy a new NIC card, so any help will be appreciated.

    Edit: I should also add that I plugged a USB wireless adapter into my computer and it worked fine, connected to the modem (which is a wireless router as well) just fine and I tested it by also connecting my Xbox wirelessly and streaming music, worked perfectly.
  2. Leeky

    Leeky TechSpot Evangelist Posts: 4,378   +98

    A new network card about the cheapest thing you can purchase, in respect of hardware.

    It sounds like your ethernet port has received some volts through it, due to the thunderstorm. Its possible it has caused more damage unknown to you currently as well.

    If it worked before the thunderstorm, and thats the only change, thats the reason.
  3. mailpup

    mailpup TS Special Forces Posts: 8,421   +217

    If you haven't already, try reinstalling the LAN driver after uninstalling the old one. This comes under the heading of, "It can't hurt to try."
  4. Pudg

    Pudg Newcomer, in training

    Stick with the wireless
  5. Lokalaskurar

    Lokalaskurar TechSpot Enthusiast Posts: 616

    "En-lieu" with what both Leeky and mailpup mentioned; it seems like the port is fried. But just in case, you should try re-installing the drivers if possible.

    Had the same problem as you a while back. Everything inside the PC worked, but still "no cable detected" kept showing up. Disassembled the network card => port was completely fried out. Soldered on a new RJ45 port, didn't work. Bought a new 10/100Mbps PCI card ($15) -- worked.

    With all respect in the world when it comes to money, a new network card can be both very cheap and very expensive. And should you get tired of the adapter, there are often cheap solutions.

    Edit:
    Fact is, even if the circuitry is somewhat fried, it often shows up in the OS anyway. ID-LPC's are pretty robust when it comes to over/under-voltage, at least in my experience :eek:

    Edit 2:
    And yes, there are diagnostic tools. I personally know that both LiteOn and Gigabyte had network diagnostics implemented into the BIOS. Try looking in your BIOS, you might just find something!
  6. LookinAround

    LookinAround TechSpot Chancellor Posts: 8,366   +167

    This trick is a longshot but worth a try (i've seen it work on a couple occasions when USB ports won't work / nothing is recognized correctly.) Under your circumstance, worth a try for the network card
    > Unplug computer from AC. Remove battery if a laptop. Let it sit a couple hours to discharge all power. Then plug it back in and retry

    You can also try reinstalling the network driver. (For uninstall, check Add/Remove Programs first. If network card is there, uninstall it using Add/Remove)
  7. westom

    westom Newcomer, in training Posts: 25

    Communication occurs in layers. Lights report the lowest layer of talking. Equivalent to your ear hearing noise. Your ear has no idea if that noise is words - and does not care. Those lights say same thing for ethernet 'noise'.

    Lights at both ends do not work? Then a connection between computer and modem does not exist. That simple. Either computer's "ear" or modem's "ear" hears nothing - is broken.

    Device Manager is only talking to the NIC's computer. Your brain can also work even though your ears do not. Device Manager only sees a working brain in the NIC. Does not know about the NICs ears.

    Power on does not create surges. A popular myth, in part, because a surge might have caused the blackout. Power restoration creates damage when myths are invented using feelings.

    If a surge existed, then it was seeking earth ground. Did your house have a 'whole house' protector in the breaker box? Then a surge could have been seeking earth incoming on AC mains and outgoing via the AT&T "required to be installled" protector. Just one example of why damage might exist.

    If you did not provide good earthing for the AT&T installed protector, then that AT&T protector might be compromised. Learn to avert future failures. Surge damage is directly traceable to human failure. Did you have sufficient earthing or a 'whole house' protector? If not, then a connection to earth might have been destructively via that ethernet port. Once that energy is inside, it will hunt for and damage paths to earth. One best path may have been via your ethernet and the AT&T 'installed for free' protector.

    Connect some other ethernet device to the modem. Do lights glow?
  8. HaLo2FrEeEk

    HaLo2FrEeEk TechSpot Enthusiast Topic Starter Posts: 225

    Goodness me, thank you for all the replies, I have a lot to try now.

    I will uninstall the drivers and reinstall them, I seem to remember something similar to this happening in the past.

    I did look in the BIOS but didn't see a diagnostic utility, only an "enable/disable" option.

    I unplugged my computer (all cables) and pulled it out, opened it and looked at the RJ45 connection. It's got a metal box around it where it connects to the motherboard, but I didn't see any tell-tale signs of damage (doesn't mean there isn't any, I know). I've left the computer unplugged for over 24 hours now as well.

    I haven't had a chance to test any other devices because the only other things I have are an Xbox 360 that works, and one that doesn't, I only have the one computer, unfortunately.

    As for the grounding, I'm not sure if I have a "whole house" protector. I would guess not since I'm in an apartment that...isn't exactly the nicest of places. I know that none of my breakers flipped, but I know that really doesn't mean anything. I knew it could happen, but I only have 1 good surge protector, the rest are just cheap power strips which I try to avoid using. The modem was plugged directly into the wall through the power, cable, AND telephone lines (not sure why, but the AT&T tech said it had to be done that way) so there are any number of possible entry points for the surge.

    At any rate, I'll try what was suggested and report back, thanks again for the help, hopefully something works.
  9. westom

    westom Newcomer, in training Posts: 25

    BIOS does not have diagnostics. BIOS is a basic IO service; will only identify errors it stumbles upon. A diagnostic is a separate program that tests all NIC functions. Only better manufacturers provide diagnostics for free with the computer.

    Almost all damage has no visual indication.

    Codes and regulations require a 'whole house' protector be installed on the AT&T line. But does not require protectors installed on the most common source of surges - AC electric. Circuit breakers do not trip during surges. Well over 300 consecutive surges can pass through before a breaker even thought about tripping.

    All plug-in protectors are equivalent. A $4 power strip with some ten cent protector parts sells for $7 in the grocery store or for $60 or $150 as a hyped (so called quality) protector. View its numeric specs. The so called 'quality' protector is equivalent to the grocery store one. Which one claims protection in its numeric specs? Does not matter what hearsay or advertising says. Only relevant is numbers in its specifications.

    A working Xbox means an ethernet port that should talk just fine to the modem. You don't care if it works. Only if lights on modem and Xbox light illuminate when an ethernet connection exists.


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