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  • intermittent Dell XPS 420 failure

    From JR Dolobson@3:633/10 to All on Wednesday, March 11, 2026 19:27:36
    I have an old Dell XPS 420 desktop that wouldn't come on some weeks ago.
    I was finally able to get it working by cutting the green wire
    connecting the power supply to motherboard and then using a switch to
    ground the green wire (on the power supply side) to ground and then
    pressing the front power button on the desktop.

    Five days ago, even the switch workaround failed and the unit failed to
    come on.

    First thing I did was remove all the cards within (video card, USB 3
    card, etc). Still no power up. I then decided to unplug the large 24
    pin connector from power supply to motherboard and, when I grounded the
    power supply green wire, the power supply came on and I believe all the
    SSD drives did too as I didn't disconnect those. I decided to try
    opening the front DVD drive and it opened right up electronically. So,
    the power supply was now working as long as the 24 pin connector was
    unplugged from the motherboard.

    I'm not sure, but it seems to me like there is a short on the
    motherboard somewhere, since the power supply won't start when the 24
    pin connector is plugged in.

    Tonight, after plugging back in the 24 pin connector, I decided to keep flipping the external toggle switch to ground while noting whether or
    not the power supply would start and the blue light would illuminate.
    Much to my surprise, it finally did, I depressed the front blue
    illuminated power button and the PC booted up. In fact, I am sending
    this message from it now.

    Now I'm not sure whether I want to turn it off again for fear I'll be
    back to no power up. Any idea what could be causing what appears to be
    an intermittent no power up issue? Can we rule out the power supply
    since it seems to activate if not plugging in the 24 pin connector (but
    it is now)?

    Any ideas would be welcome. This old 2008 desktop is my workhorse and I
    am basically lost without it. My PC and Internet demands are light, so
    that's why I am still able to use it. There are a lot of electrolytics
    on the motherboard and I understand that those fail with age and can
    cause a short. I do have an electrolytic tester, but I'd have to remove
    the motherboard to access the caps and it won't be easy. If that's even
    what could be wrong.

    Thanks in advance for any help.

    --- PyGate Linux v1.5.12
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From legg@3:633/10 to All on Thursday, March 12, 2026 09:01:03
    On Wed, 11 Mar 2026 19:27:36 -0400, JR Dolobson <dolob55J@erols.net>
    wrote:

    I have an old Dell XPS 420 desktop that wouldn't come on some weeks ago.
    I was finally able to get it working by cutting the green wire
    connecting the power supply to motherboard and then using a switch to
    ground the green wire (on the power supply side) to ground and then
    pressing the front power button on the desktop.

    Five days ago, even the switch workaround failed and the unit failed to
    come on.

    First thing I did was remove all the cards within (video card, USB 3
    card, etc). Still no power up. I then decided to unplug the large 24
    pin connector from power supply to motherboard and, when I grounded the >power supply green wire, the power supply came on and I believe all the
    SSD drives did too as I didn't disconnect those. I decided to try
    opening the front DVD drive and it opened right up electronically. So,
    the power supply was now working as long as the 24 pin connector was >unplugged from the motherboard.

    I'm not sure, but it seems to me like there is a short on the
    motherboard somewhere, since the power supply won't start when the 24
    pin connector is plugged in.

    Tonight, after plugging back in the 24 pin connector, I decided to keep >flipping the external toggle switch to ground while noting whether or
    not the power supply would start and the blue light would illuminate.
    Much to my surprise, it finally did, I depressed the front blue
    illuminated power button and the PC booted up. In fact, I am sending
    this message from it now.

    Now I'm not sure whether I want to turn it off again for fear I'll be
    back to no power up. Any idea what could be causing what appears to be
    an intermittent no power up issue? Can we rule out the power supply
    since it seems to activate if not plugging in the 24 pin connector (but
    it is now)?

    Any ideas would be welcome. This old 2008 desktop is my workhorse and I
    am basically lost without it. My PC and Internet demands are light, so >that's why I am still able to use it. There are a lot of electrolytics
    on the motherboard and I understand that those fail with age and can
    cause a short. I do have an electrolytic tester, but I'd have to remove
    the motherboard to access the caps and it won't be easy. If that's even >what could be wrong.

    Thanks in advance for any help.

    Replacing the generic power supply is strp 1.

    You can't see the sequencing or quality of it's housekeeping and
    switchable outputs. The MCU can.

    RL

    --- PyGate Linux v1.5.12
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Chuck@3:633/10 to All on Thursday, March 12, 2026 11:17:44
    On Thu, 12 Mar 2026 09:01:03 -0400, legg <legg@nospam.magma.ca> wrote:

    On Wed, 11 Mar 2026 19:27:36 -0400, JR Dolobson <dolob55J@erols.net>
    wrote:

    I have an old Dell XPS 420 desktop that wouldn't come on some weeks ago.
    I was finally able to get it working by cutting the green wire >>connecting the power supply to motherboard and then using a switch to >>ground the green wire (on the power supply side) to ground and then >>pressing the front power button on the desktop.

    Five days ago, even the switch workaround failed and the unit failed to >>come on.

    First thing I did was remove all the cards within (video card, USB 3
    card, etc). Still no power up. I then decided to unplug the large 24
    pin connector from power supply to motherboard and, when I grounded the >>power supply green wire, the power supply came on and I believe all the >>SSD drives did too as I didn't disconnect those. I decided to try
    opening the front DVD drive and it opened right up electronically. So, >>the power supply was now working as long as the 24 pin connector was >>unplugged from the motherboard.

    I'm not sure, but it seems to me like there is a short on the
    motherboard somewhere, since the power supply won't start when the 24
    pin connector is plugged in.

    Tonight, after plugging back in the 24 pin connector, I decided to keep >>flipping the external toggle switch to ground while noting whether or
    not the power supply would start and the blue light would illuminate.
    Much to my surprise, it finally did, I depressed the front blue >>illuminated power button and the PC booted up. In fact, I am sending
    this message from it now.

    Now I'm not sure whether I want to turn it off again for fear I'll be
    back to no power up. Any idea what could be causing what appears to be
    an intermittent no power up issue? Can we rule out the power supply
    since it seems to activate if not plugging in the 24 pin connector (but
    it is now)?

    Any ideas would be welcome. This old 2008 desktop is my workhorse and I >>am basically lost without it. My PC and Internet demands are light, so >>that's why I am still able to use it. There are a lot of electrolytics
    on the motherboard and I understand that those fail with age and can
    cause a short. I do have an electrolytic tester, but I'd have to remove >>the motherboard to access the caps and it won't be easy. If that's even >>what could be wrong.

    Thanks in advance for any help.

    Replacing the generic power supply is strp 1.

    You can't see the sequencing or quality of it's housekeeping and
    switchable outputs. The MCU can.

    RL
    I agree, these are known for defective power supplies. I used to
    replace bad electrolytic capacitors in these supplies.

    --- PyGate Linux v1.5.12
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From JR Dolobson@3:633/10 to All on Friday, March 13, 2026 07:58:26
    On 3/12/26 12:17 PM, Chuck wrote:
    On Thu, 12 Mar 2026 09:01:03 -0400, legg <legg@nospam.magma.ca> wrote:

    On Wed, 11 Mar 2026 19:27:36 -0400, JR Dolobson <dolob55J@erols.net>
    wrote:

    I have an old Dell XPS 420 desktop that wouldn't come on some weeks ago. >>> I was finally able to get it working by cutting the green wire
    connecting the power supply to motherboard and then using a switch to
    ground the green wire (on the power supply side) to ground and then
    pressing the front power button on the desktop.

    Five days ago, even the switch workaround failed and the unit failed to
    come on.

    First thing I did was remove all the cards within (video card, USB 3
    card, etc). Still no power up. I then decided to unplug the large 24
    pin connector from power supply to motherboard and, when I grounded the
    power supply green wire, the power supply came on and I believe all the
    SSD drives did too as I didn't disconnect those. I decided to try
    opening the front DVD drive and it opened right up electronically. So,
    the power supply was now working as long as the 24 pin connector was
    unplugged from the motherboard.

    I'm not sure, but it seems to me like there is a short on the
    motherboard somewhere, since the power supply won't start when the 24
    pin connector is plugged in.

    Tonight, after plugging back in the 24 pin connector, I decided to keep
    flipping the external toggle switch to ground while noting whether or
    not the power supply would start and the blue light would illuminate.
    Much to my surprise, it finally did, I depressed the front blue
    illuminated power button and the PC booted up. In fact, I am sending
    this message from it now.

    Now I'm not sure whether I want to turn it off again for fear I'll be
    back to no power up. Any idea what could be causing what appears to be
    an intermittent no power up issue? Can we rule out the power supply
    since it seems to activate if not plugging in the 24 pin connector (but
    it is now)?

    Any ideas would be welcome. This old 2008 desktop is my workhorse and I >>> am basically lost without it. My PC and Internet demands are light, so
    that's why I am still able to use it. There are a lot of electrolytics
    on the motherboard and I understand that those fail with age and can
    cause a short. I do have an electrolytic tester, but I'd have to remove >>> the motherboard to access the caps and it won't be easy. If that's even >>> what could be wrong.

    Thanks in advance for any help.

    Replacing the generic power supply is strp 1.

    You can't see the sequencing or quality of it's housekeeping and
    switchable outputs. The MCU can.

    RL
    I agree, these are known for defective power supplies. I used to
    replace bad electrolytic capacitors in these supplies.

    That was the fault, the PSU! Replaced it and all back to normal. The existing one still works, but only when the 24 pin MB connector wasn't
    plugged in. At some point, I'll guess I'll open it up and start
    checking for bad electrolytics. Thanks again for both of your help.

    --- PyGate Linux v1.5.13
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)