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Fluorescent Lights Magically Activates iMac?

Posted by Cliff on from the weird-goings-on-here dept.

bats asks: "In my computer room at home, I have several machines -- and a fluorescent desk lamp. Among my various boxen is an iMac DV (slot loading) circa 1999. Its configured to go into power saving mode, but respond to wake-on-lan packets. The weird thing is this: If I flip on the fluorescent desk lamp, the sleeping iMac will suddenly wake up! This happens with 100% consistency. The desk lamp is plugged into a power strip and into the wall. The iMac is plugged into a UPS and then into the wall. The network switch for the room is near the desk lamp (1-2 feet) but the iMac is some distance away (8-10 feet). My question is: WTF?! How the heck does the iMac know when the light comes on? It seems like it must be some power spike in the AC or noise on the network interface. However, the power strip and the UPS should block an AC spike and the chance of electrical noise in the cat-5 looking like a wake-on-lan packet seem more than miniscule. So again I ask you, dear AskSlashdot reader, WTF?! I await conspiracy theories, pseudo-science, wild rantings, and hopefully, the right answer."

10 of 108 comments (clear)

  1. logical process... by invictus · · Score: 5, Insightful

    one way to go about figuring it out, i would think, would be to remove the mac from the lan, turn on the lamp... does it wake up? if it does you can rule out WOL. If it doesn't, then it seems to be something on the network. Is the hub/switch plugged into the same surge protector as well as being perhaps too close? just step through the problem.

    --
    --Ks9
  2. i had this problem once... by jnana · · Score: 5, Funny

    it turns that some of my body thetans had gotten trapped at the electrical outlet, and any kind of a disruption to the old AC current would cause them to send out signals that would wake my laptop. I couldn't figure out what was going on, so I called my counselor at the Church of Scientology. He sent over some of their scientists, and they turned my place upside down with a special device, like an e-meter, that detects escaped body thetans. I'd recommend you give them a call. It'll only cost you about US $15,000.

  3. Easy fix by lightspawn · · Score: 4, Funny

    Just pop in Celine Dion's "copycally-challenged" CD before you turn off the iMac.

  4. Does it have IR port? by marat · · Score: 4, Interesting

    Probably it's receiving some nonsence data when you switch on the lamp. Also, UPS might be trying to tell you something via it's COM port connection or whatever. Network interference via switch is also possible. Plug out one by one and check.

    My PC turned on after any phone ring (very disturbing while installing some new hardware :( ) though they was not 'Wake up on ring' option in BIOS. Turned out that 'Wake up on LAN' also works as 'Wake up on ring'.

    BTW does you mac have external modem? Probably your modem tells RING each time you turn on the lamp. Easy to check with any terminal program.

  5. does it by fferreres · · Score: 5, Funny

    come with a compact flash reader? Oh...

    --
    unfinished: (adj.)
  6. Mobiles phones by cowbutt · · Score: 4, Interesting
    I woke up early one morning to the sound of my electronic metronome going tick-tick-tick-tock quite loudly. My first thought was that I'd somehow managed to leave it on before going to bed and sleeping right through it. When I checked, I found that my old Nokia 6150 was charging right next to it and the aerial was pointing right at it.

    My guess is that one of the periodic cell checkin transmissions induced enough of a current in the on/off circuit that the metronome decided to switch on. Spooky!

    --

  7. Format of a Wake-On-Lan Frame by uofa1993engrmath · · Score: 5, Informative

    > The wake-on-lan must just detect ANY activity on the ethernet, not a valid packet.

    IBM has a White Paper, Wake up to Wake-on-Lan which describes the specific format of a Wake-Up packet (6 bytes of F (XX'FF') followed by a 48-bit target address repeated at least 8 times). Even if the target address was a broadcast address, I don't see how this could be reliably generated by the starting of a fluorescent lamp. Plus, your average LAN has a whole bunch of traffic going on all the time anyway.

    I have an iMac DV (graphite), and I DON'T have it plugged into a network, and it's NOT configured for Wake-on-Lan, nor is it configured to wake on phone rings, and I don't have any infrared devices that I know about, and I have an optical mouse, so it won't wake if the mouse gets moved, and it still wakes up when I vaccum my living room or turn on my slide projector.

  8. mouse + light by daniel2000 · · Score: 5, Insightful

    if you have a mouse anywhere near the light and then some light could be getting into the mouse makeing it think it has moved.

    Try the experiment with the mouse covered up with a rug and switching the light on.

    I had an experiance where at certain times of the day the mouse cursor would go a bit funny. took a while to work out it was when the sun peeped throught the window at just the right angle...

  9. Your UPS is sending a heads up ... by kousik · · Score: 4, Interesting

    Is your UPS connected to the network
    so that it can inform the machines
    when there is a change of status of
    power line? Maybe when the light is
    turned on, the power surge makes UPS
    send a packet to your network? Just
    guessing.

  10. PEBKAC by KFury · · Score: 5, Funny

    This is a new iMac, right?

    Okay, look in your office, and put your hand on the lamp. Is your hand resting on the thing with a rounded base, a stalk, and a flourescent emitter at the end? That's your computer. Don't worry, a lot of people make that mistake.

    --

    Kevin Fox