Computer Clock losing time whilst under power.

Discussion in 'Computer Support' started by Bill Capp, Mar 27, 2005.

  1. Bill Capp

    Bill Capp Guest

    When I first booted up today I noticed the computer clock was a few
    seconds slow.
    But it then started to lose time, 20 seconds in the next hour.
    Because the clock is losing time whilst the computer is switched on,
    under power from the mains, is there a more serious problem that a
    motherboard battery failure?
    I would have thought that battery failure would only have affected the
    computer whilst it was switched off.
    I would appreciate any help.
    Thanks
    Bill Capp.
     
    Bill Capp, Mar 27, 2005
    #1
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  2. the cmos battery is responsible for the clock on your MOBO
    its not a big deal to swap it over, just be careful not to create a ststic
    charge when taking it out
     
    [email protected], Mar 27, 2005
    #2
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  3. Bill Capp

    °Mike° Guest

    If it is losing time when powered on, then the cause is
    a software issue, with prime suspects being antivirus (Norton?)
    or something that takes up a inordinate amount of processor
    time. Check out the 1001 processes that you have running
    at startup.
     
    °Mike°, Mar 27, 2005
    #3
  4. Bill Capp

    JANA Guest

    The BIOS battery is one thing that can cause a real time accuracy problem.
    In some mother boards, the CMOS clock has its own crystal for its real time
    clocking. In some, the crystal is built in to its clocking chip. In some
    mother boards there is also a trimmer capacitor for the adjustment of the
    clock. Over time, if the PC is an older one, it is possible that the
    crystal's characteristics has drifted a little. If the crystal has gone
    defective, the time would be far out all the time, or the real time clock
    would stop working.

    The procedure to adjust the crystal would involved using a frequency counter
    with at least a 6 digit or greater readout, with a stability factor of at
    least 10 ppm or better, and using a high impedance probe to the real time
    test point. In some of these, the test point is not at the fundamental
    frequency of the real time clock, while in others it is. The test point may
    not be a stand-up terminal, as like in most electronic circuit boards. You
    would have to know where it is, and what to expect for your particular
    board. In most of these clocks, the fundamental crystal frequency is 32,768
    Hz.

    On most boards, the frequency adjustment is done with a small trimmer
    capacitor. In many of the newer boards, the adjustment is done with a
    software correction at the time that the firmware was burned in to the clock
    chip during the manufacture process.

    A crude way to adjust the clock, is if you know where and have a trimmer cap
    on the mother board for it, is to move the trimmer a few degrees of
    rotation, and keep track if the time is going faster or slower. Then you
    have to keep adjusting it appropriately until you have reached your goal.

    --

    JANA
    _____


    When I first booted up today I noticed the computer clock was a few
    seconds slow.
    But it then started to lose time, 20 seconds in the next hour.
    Because the clock is losing time whilst the computer is switched on,
    under power from the mains, is there a more serious problem that a
    motherboard battery failure?
    I would have thought that battery failure would only have affected the
    computer whilst it was switched off.
    I would appreciate any help.
    Thanks
    Bill Capp.
     
    JANA, Mar 27, 2005
    #4
  5. Bill Capp

    Oldus Fartus Guest

    JANA wrote:

    snipped
    Do you want to list the motherboards which have an adjustment trimmer?
    I have not seen one since the 386 days.
     
    Oldus Fartus, Mar 27, 2005
    #5
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