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When it always blows fuses Was: PC power supply problem

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  • csakima
    Sounds almost like the power output trannys are blown. Thus putting the transformer DC across the power lines. A dead short, since DC wise, the transformer
    Message 1 of 2 , Dec 4, 2003
      Sounds almost like the power output trannys are blown.   Thus putting the transformer DC across the power lines.  A dead short, since DC wise, the transformer is only a piece of wire.   Try measure the ohmage across from VCC to ground in the primary driver side.  And go from there.
       
      What I do sometimes is .... put the fuse back in ... and wire a 100W (or more) light bulb in series with the power supply and the AC mains line input.   And plug it in.   Any attempt for the supply to blow another fuse will cause the 100 watter to light up .... absorbing the fuse-blow-shock.   When you find the problem, the 100 Watter will dim ... since the normal operating current of the power supply is low.   That's a trick I use for fuse-blowing problems.

      Curtis
       
      ---------------------
      Make her feel special this coming holiday season with flowers
      www.flowerson55.com
       

       
      ----- Original Message -----
      Sent: Thursday, December 04, 2003 5:31 AM
      Subject: Re: [Electronics_101] Re: PC power supply problem

      Yes, I replaced the fuse with a similar but again it blows up.Switching regulator is 2SK7565 MOSFETon which I have the datasheet.As you said I must check the Caps. and also high value,high wattage resistors.Yes, I connected a dummy load (10ohms,25W resistor) to +5V rail and a dual filament auto head lamp to +12V rail.Also I powered the unit through series 100W lamp bulb. This is just to reduce the current to the unit.But still it did not work.The reason I want to repair this is to use as a bench power supply. 
    • manifold
      Does that really work for switching supplies? The inrush current is pretty high which would light the bulb and cut the power. I would think it would just sit
      Message 2 of 2 , Dec 4, 2003
        Does that really work for switching supplies? The inrush current is
        pretty high which would light the bulb and cut the power. I would
        think it would just sit there and burp on and off quickly.

        --- In Electronics_101@yahoogroups.com, "csakima" <csakima@n...> wrote:
        > Sounds almost like the power output trannys are blown. Thus
        putting the transformer DC across the power lines. A dead short,
        since DC wise, the transformer is only a piece of wire. Try measure
        the ohmage across from VCC to ground in the primary driver side. And
        go from there.
        >
        > What I do sometimes is .... put the fuse back in ... and wire a 100W
        (or more) light bulb in series with the power supply and the AC mains
        line input. And plug it in. Any attempt for the supply to blow
        another fuse will cause the 100 watter to light up .... absorbing the
        fuse-blow-shock. When you find the problem, the 100 Watter will dim
        ... since the normal operating current of the power supply is low.
        That's a trick I use for fuse-blowing problems.
        >
        > Curtis
        >
        > ---------------------
        > Make her feel special this coming holiday season with flowers
        > www.flowerson55.com
        >
        >
        >
        > ----- Original Message -----
        > From: ravi sumith
        > To: Electronics_101@yahoogroups.com
        > Sent: Thursday, December 04, 2003 5:31 AM
        > Subject: Re: [Electronics_101] Re: PC power supply problem
        >
        >
        > Yes, I replaced the fuse with a similar but again it blows
        up.Switching regulator is 2SK7565 MOSFETon which I have the
        datasheet.As you said I must check the Caps. and also high value,high
        wattage resistors.Yes, I connected a dummy load (10ohms,25W resistor)
        to +5V rail and a dual filament auto head lamp to +12V rail.Also I
        powered the unit through series 100W lamp bulb. This is just to reduce
        the current to the unit.But still it did not work.The reason I want to
        repair this is to use as a bench power supply.
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