Dell Dimension 2400 No Post

[bigbeark]

I have my son's old Dell Dimension 2400, which stopped posting last year.
All caps are Rubycon and none are bulged. ESR tests fine.

I have removed the board from the case and using my Post Card I observe there is no display of Post Codes at all!

The board does power up and that IBM heatsink/fan runs at max speed.

I am thinking that one or more of the MOSFETS is open circuit or grounded.

There are six in total, three on each side of the L-shaped heatsink. It looks like I can remove the heatsink by removing the screw that atttach the MOSFETS to the heatsink.

Can anyone offer advice on how to test these MOSFETS or are they likely the problem at all? The MOSFETS are labelled 70L02P and 408401.

[retiredcaps]

Re: Dell Dimension 2400 No Post

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Can anyone offer advice on how to test these MOSFETS or are they likely the problem at all?

I do a simple, in circuit, resistance test between S-G, S-D, and G-D. Any reading under 30 ohms suggests a short and the component should be desoldered and verified out of circuit.

Others have done it this way.

http://www.4qdtec.com/mostest.html