Dell Dimension 2400 -- Won\'t Power On

[gemiss]

My Dell Dimension 2400 Desktop will not power on.

 

[C12Friedman]

Welcome to Tom's Hardware Forums,
There are quite a few possible reasons, because of the age, I will suggest replacement of the CMOS battery (little watch battery on the motherboard) as a first course of action - not expensive, can be purchased at your local watch/hearing aid battery retailer.
Your power supply may be dead at this time also as OEM PSU's aren't really designed to last more than four or five years, anything over that, you're doing good. I can go over your options there but I would do the CMOS battery first.
Good luck
Afterthought: At the back of your computer there are four led's - are any of them lit when you attempt to power on?

 

[gemiss]

Hi,
Tried replacing the battery but still nothing happens when I press the start button on the tower. Thanks.

gemiss

 

[C12Friedman]

Back to the back of the computer, there are four led's on the motherboard (I have one in my lap as I type this) next to where your mouse and keyboard plug in - are any lit at all? Any other lights?
Just want to make sure before you test the PSU (next step)

 

[gemiss]

There are no lights whatsoever that come on when I press the start button. There is not even a click when I push the start button. I have checked the start button for continuity and it checks OK.

 

[C12Friedman]

You do have a multimeter, that's good. A very basic test for the PSU is to unplug the PSU and unplug the 20 and 4 pin connectors from the motherboard. Using a paperclip (or length of wire), jump the green wire to a black wire on the PSU's 20 pin connector. Plug in the PSU, see if anything comes on (notably the fan in the PSU).
If the fan comes on, this guide shows you the pinout for your voltages,
http://www.smpspowersupply.com/connectors-pinouts.html
check those with the multimeter.

 

[gemiss]

When I jump the green and black wires on the 20 pin connector, I do get the fan to run. When I checked the voltage from from the connector, the only voltage reading
I could get was from the purple wire and the green wire. The reading was not steady - between 2 and 3 volts each.

 

[C12Friedman]

Just to ensure, did you take the readings while the green and black were jumped, I'm thinking perhaps not because of the voltage readings. If not, check while jumped.
If you did check them while jumped, your PSU can be pronounced dead and replacement would be in order. The purple should be at 5v anyway so that's definately not a good sign.

 

[gemiss]

After I read the directions more observantly, I got it jumped OK and all the reading came very close to the required voltage readings. so it appears the PSU is OK. Where do we go from here?

 

[C12Friedman]

Okay, here's the next step... Testing the motherboard. For this, you'll want to unplug your connectors (you might number them or take a picture or use some other method to remember where they go when reattached) from the motherboard (front panel headers, IDE connectors etc) so the only thing plugged into your motherboard is ram, the CPU with heatsink and your two power connectors. Try to start the computer by arcing the pwr connectors (don't jump it, just arc it) pins 6&8 on the diagram below.
http://www.fixya.com/support/t505171-dell_2400_motherboard_case_connections
We are hoping to get some kind of beep or light sequence in the back which will tell us what to look at - lights/issues shown here
http://support.dell.com/support/edocs/systems/dim2400/en/sm_en/advtshoo.htm

 

[C12Friedman]

Where did we get to? Anything?

 

[gemiss]

I haven't been able to get the motherboard testing done yet. I'll get back to you just as soon as I can get it done. Thanks.

 

[gemiss]

I'm not sure I know what you mean by arcing the power connectors instead of jumping them.

 

[C12Friedman]

You just wantto touch the two for a moment, not keep contact

 

[gemiss]

Thanks, I'll get back to you as soon as I can.

 

[gemiss]

Dell Computer will not power on! I haven'
t been able to perform the last test yet. As soon as I get it done, I'll get back to you. Thanks.

gemiss

 

[gemiss]

Hi, I made the test on the motherboard. No beeps and the only light that came on was the green power indicator light. Thanks.
gemiss

 

[C12Friedman]

That is not good - I'm thinking a mobo funeral is in order but, there may be a problem that has a (somewhat) easy fix... Look at the cylinders (capacitors) around the large metal heatsink on the motherboard, are any bulging or leaking at all?

 

[gemiss]

Can't see any leaking or bulging capacitors. They all look pretty good.

 

[C12Friedman]

Shucks, that was my last grasp... I suppose you could look into "re-flowing" your motherboard but I honestly don't think it's worth it. The data on the hard drive should still be accessible through a USB adapter so keep that. The system itself is old enough that repair is probably not worth it either.
I was hoping for a better outcome...

 

[gemiss]

Thanks so very much for your time and advise. Sounds like it is gone - might be good for parts. Thanks again.

gemiss

P.s. I learned quite a bit.