Re: PC Struck by Lightning?!

Discussion in 'A+ Certification' started by w_tom, Sep 2, 2005.

  1. w_tom

    w_tom Guest

    First, it is routine to run equipment during a thunderstorm
    without damage. But that assumes the human has installed
    inexpensive solutions and did not spend greater money on
    ineffective plug-in solutions.

    You don't even know if the power supply is working.
    Spinning fans tell you nothing useful other than the power
    cord is connected to the wall.

    First confirm the computer is built on a properly
    functioning foundation. A multimeter confirms power supply
    integrity. Then move on to verifying integrity of other
    components. Without first confirming power supply integrity,
    then all other solutions are but secondary and may be futile.

    Meter may find a problem even with the power supply
    controller - which is another component of the power supply
    system. Power supply is only one component of that system.
    But to see this, you need that multimeter and basic knowledge
    as found in two previous posts:
    "Computer doesnt start at all" in alt.comp.hardware on 10
    Jan 2004 at
    http://tinyurl.com/2t69q and
    "I think my power supply is dead" in alt.comp.hardware on 5
    Feb 2004 at
    http://tinyurl.com/yvbw9

    One does not even remove a single component until the power
    cord is remove from wall. Even when powered off, many
    components still have electricity if power cord connects to
    wall receptacle. Moving any component when electrically hot
    is destructive (except where that component is designed
    specifically to be removed hot such as a USB cable).

    Dave Hardenbrook wrote:
    > One of my clients made the mistake of running their system during a
    > thunderstorm. This was about three weeks ago, and since then the system
    > has gradually degraded in performance -- First it worked okay, then it
    > would fail to boot to Windows normally (I thought maybe all that was
    > needed was System Restore or Recovery Console), now the system halts at
    > POST with the error: "Award Bootblock BIOS ROM checksum error". Is
    > there a chance that it's just the CMOS battery, or is it pretty certain
    > that lightning did strike and the mobo is fried? And if the mobo is
    > toast, are the other components probably gone as well?
    >
    > --
    > Dave
    w_tom, Sep 2, 2005
    #1
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  2. w_tom

    w_tom Guest

    Point 1: a spinning fan tells us nothing useful as correctly
    posted. For example, +12 volts could be only +8 volts or what
    you called "might not be working well". Either +12 volts is
    working "well and right", or it is not working at all. +12
    volts at only 8 volts is not working at all. Nada. Fan would
    spin. Computer and power supply still don't work. That is
    basic electrical knowledge.

    Then it gets more interesting. Many power supplies don't
    power a fan from +12 volts; as you have assumed. Many power
    supplies power the fan from -12 volts. This provides a
    minimum load for the -12 volt power supply chip. +12 volts
    output might not exist. Meanwhile -12 volts could still be
    spinning fan. Just a second basic electrical reason why a
    spinning fan tells us nothing useful.


    Point 2: informed technicians don't disconnect anything from
    computer when doing analysis. Standard procedure - don't
    change anything before collecting the facts - just like a
    crime scene. Power supply integrity is verified without
    disconnecting a power supply; that being common knowledge for
    electronic techs. A power supply is measured with the 3.5
    digit multimeter while connected to a computer. This also so
    that the rest of that power supply 'system' can be verified.
    Statements about testing a supply without load are totally
    irrelevant and imply poor debugging habits.

    Again, there is no such thing as a power supply working if
    it is not working "well" or "right". Supply must output
    sufficient voltage which is why that 3.5 digit multimeter is
    necessary - as tool as essential as a screwdriver. Totally
    erroneous assumption that a spinning fans reports something
    useful. A spinning fan only suggests AC power is available
    from a wall receptacle. Multiple reasons for why that
    spinning fan reports nothing useful were provided with basic
    electronic knowledge.

    Point 3 for the Original Poster: first, measure those power
    supply voltages as described in previous posts. Even if
    recorded numbers means nothing, still, more informed posters
    can now provide informed replies. Currently every post is
    nothing more than wild speculation because we don't have those
    power supply voltages. Replies can only be as good as the
    information provided - the numbers.

    Second, the CMOS battery is also verified using that
    multimeter. The typical 3 volt CMOS battery should measure 3
    volts or more. If it measures 2.8 volts, it is still not a
    reason for system problems. Again, numbers for the meter
    identify problems immediately with bad repair habits such as
    shotgunning. Either that battery is clearly defective OR it
    is not. No reason to first buy a new battery only to guess a
    battery might be defective.

    Barry Watzman wrote:
    > Re: "Spinning fans tell you nothing useful other than the power cord is
    > connected to the wall."
    >
    > Not true. The fans run from the +12 volt supply, on the secondary side
    > of the switcher. So if they work, then at some leve, the power supply
    > is working. Might not be working "well" or "right", but it's working.
    >
    > Also, many supplies will not work unless at least some outputs have some
    > level of load connected. You cannot, usually, measure the voltages with
    > the power supply not connected to a load.
    w_tom, Sep 4, 2005
    #2
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