PSU & on/off inter-operation ? - Hardware

This is a discussion on PSU & on/off inter-operation ? - Hardware ; This PC that I aquired had a problem sometimes with the VDU-start-up, BIOS-start-up ... Sometimes the display wouldn't "start"; one of the many Mercer models. Sometimes this could be 'fixed' by powering the display ON/OFF, after the PC had started ...

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Thread: PSU & on/off inter-operation ?

  1. PSU & on/off inter-operation ?

    This PC that I aquired had a problem sometimes with the VDU-start-up,
    BIOS-start-up ...

    Sometimes the display wouldn't "start"; one of the many Mercer models.

    Sometimes this could be 'fixed' by powering the display ON/OFF, after
    the PC had started booting. Which can be problematic when you want
    to select at boot-time.
    The display has got some strange action, in that it takes a second for its
    power light to show on or off. As if it's got a PSU which takes time to
    stabilise/re-discharge.
    Also when it's started from cold, it clicks [sound] and flashes its power
    light, for some time, before it starts properly. It seems to need to warm
    up.

    The similar smart-ass PSU-control, where the 'on/off' button is
    not hardwired, but is just a 'request/suggestion' signal, is problematic.

    So with the CPU-Bios & the VDU & the ON/OFF-PSU forming a trio
    of inter-related 'agents', there's lots of scope for problems/confusion.
    Ie. compare to the old-days when the CPU-Bios, VDU, PSU+switch
    all were more independant.

    I've been away for a week [the 3V cell still measures 3V] and when I
    tried to boot, it started its VDU clicking/pumping. When the VDU didn't
    display after 5 minutes of continual 'pumping' I tried activating the on/off
    PC switch and observed the delayed action of the PSU fan.
    My previous understanding was that the VDU needed to warm up,
    before receiving display signals.

    Later on & offing of the VDU and PC, showed the PSU fan to be dead.
    Then when I plugged the PSU [the double-row (I think 20 pin) type] to
    another MOBO which works with the non-double-row power-connector,
    that MOBO failed to show 'power'.

    Since the PSU gets a signal [other than the on/off switch] I apparently
    can't just assume the the PSU is defective.

    Q - how do I test the PSU ?

    Thanks for any info,

    == Chris Glur.



  2. Re: PSU & on/off inter-operation ?

    In comp.sys.ibm.pc.hardware.misc fld@informatik.uni-bremen.de wrote:
    > This PC that I aquired had a problem sometimes with the VDU-start-up,
    > BIOS-start-up ...


    > Sometimes the display wouldn't "start"; one of the many Mercer models.


    > Sometimes this could be 'fixed' by powering the display ON/OFF, after
    > the PC had started booting. Which can be problematic when you want
    > to select at boot-time.
    > The display has got some strange action, in that it takes a second for its
    > power light to show on or off. As if it's got a PSU which takes time to
    > stabilise/re-discharge.
    > Also when it's started from cold, it clicks [sound] and flashes its power
    > light, for some time, before it starts properly. It seems to need to warm
    > up.


    > The similar smart-ass PSU-control, where the 'on/off' button is
    > not hardwired, but is just a 'request/suggestion' signal, is problematic.


    > So with the CPU-Bios & the VDU & the ON/OFF-PSU forming a trio
    > of inter-related 'agents', there's lots of scope for problems/confusion.
    > Ie. compare to the old-days when the CPU-Bios, VDU, PSU+switch
    > all were more independant.


    > I've been away for a week [the 3V cell still measures 3V] and when I
    > tried to boot, it started its VDU clicking/pumping. When the VDU didn't
    > display after 5 minutes of continual 'pumping' I tried activating the on/off
    > PC switch and observed the delayed action of the PSU fan.
    > My previous understanding was that the VDU needed to warm up,
    > before receiving display signals.


    > Later on & offing of the VDU and PC, showed the PSU fan to be dead.
    > Then when I plugged the PSU [the double-row (I think 20 pin) type] to
    > another MOBO which works with the non-double-row power-connector,
    > that MOBO failed to show 'power'.


    > Since the PSU gets a signal [other than the on/off switch] I apparently
    > can't just assume the the PSU is defective.


    > Q - how do I test the PSU ?


    > Thanks for any info,


    > == Chris Glur.


    Don't do this yourself, unless you have extensive experience
    testing and repairing electronics. It may be risky, since you
    can find up to a potential 450V inside that PSU.

    Arno


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