# Possible bad Dell power supply confirmation



## Outbackcamprd (Dec 9, 2011)

Hi all,

I have a dell xps 400 computer that will not power up. The symptoms are:

1. Power lamp flashes amber when depressed to power up.
2. Fans or drives do not start.
3. One light on the mother board illuminates green and has the title: AUX_POWER_LED.
4. The flashing amber light will stop after the power button is held depressed for the usual 10 second power down time.

My concern is that I researched this problem with my original power supply and all of the forums generally advised to replace the power supply. I purchased one from eBay using the exact CN number and after installation the same symptoms occur. Is there any way to check the voltages on the power supply to find out which one is not active. I have the necessary test equipment but cannot locate any pinout diagrams or configuration the power supply must be set in to test. Is there a test jumper that must be installed to get the power supply to power up? Does the processor heat sink need to be installed to allow the power supply to activate, only for a short duration test?

Any suggestions would be useful as I am about ready to scrap the unit if I cannot fix it.

Many thanks


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## Tyree (May 10, 2009)

Try unplugging the PSU power cord from the PSU for a few minuted.
Replacing the Dell PSU with another Dell PSU form E-Bay was probably not the best option. 
SeaSonic-XFX-Corsair (not the CX or GS Series) are top quality PSU's.


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## Wrench97 (May 10, 2008)

See this sticky for testing the PSU> http://www.techsupportforum.com/forums/f210/test-your-power-supply-with-a-multi-meter-151526.html

Do any of the 4 diagnostic lights on the front panel light up?


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## Outbackcamprd (Dec 9, 2011)

Oh yes, I did forget to mention that the diag lights do not illuminate at any time.


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## Wrench97 (May 10, 2008)

If the PSU checks out it'll most likely be a motherboard, outside chance it could be the front panel board(the one behind the power button with the diag lights, USB ports and front audio ports in it).


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## Outbackcamprd (Dec 9, 2011)

I checked both power supplies and both showed the same symptoms. The VSB 5v was good, the PS_ON behavior was as expected, but the POWER_OK remained at 0v. So I either have two bad supplies or something else is causing the problem. 

Any thoughts?


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## dai (Jul 2, 2004)

try starting it by touching the 2 pins on the m/board the front button connects to,for a fraction of a second with a screwdriver

what do the fans do when you try to start


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## Wrench97 (May 10, 2008)

Are you checking with the PSU hooked to the the motherboard?

See if you can find a Front I/O panel cheap and try swapping it out looks like this > Dell FK463, FJ470, WS390 Powerboard Precision Workstation 390 Control Panel

How to R & R> Documentation


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## Outbackcamprd (Dec 9, 2011)

I have looked for pins that are connected to the start button but it looks like the button wires are bundled with wires from the diagnostic board and connect to a separate plug in a board plugged into the mother board so I cannot reliably tell exactly what wires are associated with the start button. Otherwise I would try the short out test.

All tests and measurements are done with the PSU installed and connected to the mother board.


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## Wrench97 (May 10, 2008)

That is the front I/O panel, it's a 38 pin ribbon trying to get to the pins on the motherboard is almost impossible with the CPU cooler installed.

I have a known good I/O panel I use to troubleshoot with as any other way on those setups is almost impossible.


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