Need Help!!! My Dimension 4700 won't start!!!

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Need Help!!! My Dimension 4700 won't start!!!

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Hi,

I'm in dire situation. My Dimension 4700 won't start. It was fine just a few hours ago.

The symptoms are as follows:

When I turn the switch on, the power will turn on but the computer doesn't seem to progress from there - nothing comes up on the monitor.

Two things seem to be different from usual: (1) the fan is noticeably noisier than before, (2) the hard drive doesn't seem to be switched on, because I hear no spinning sound of HDD and also the green LED light that comes on when HDD spins does not come on.

What could be wrong?  Where should I take it?

All Replies
  • runner_up  

    Is the power button LED, solid green, blinking green, solid amber, blinking amber, or off?

    Check the reading of the diagnostic LIGHTS on the back panel?

    Are there any error messages, or 'Beeps'?

    Bev.

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • The power button LED is solid amber.

    Where are the diagnostic lights located? My Dell does not have any diagnostic lights on the back panel.

    There are no error messages or beeps, because nothing shows up on the monitor - not even the Bios setup message error that usually pops up when there is something wrong with the hardware.

  • I think I found the diagnostic lights. I didn't recognize them because they were all turned off.

    According to the service manual, if all of the diagnostic lights are off, it means a pre-BIOS failure.

    Where do I go from here?

  • runner_up  

    Try connecting the power cord directly into a different power outlet, no difference and if you are comfortable working around computers, you could try the following:

    Unplug the cord from the power supply, hold the power button in for about 15/20 seconds, open the case, unplug the 24-pin power connector from the motherboard and jump the Green wire to one of the Black wires, reconnect the power cord and power the system, if power supply's fan and the hard drive runs, then the PSU should be good.

    Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper.

    Power supply checks out and the system still does not work, again remove the power cord, hold the power button in for several seconds to discharge the residue power, reconnect the 24-pin connector to the motherboard.

    Remove all the PCI cards, the video card [if applicable], memory, all peripherals, disconnect the data and power cables to all the drives, check that the front panel cable is connected to motherboard, with nothing else connected to the system, reconnect the power cable and power the system on.

    If you do not get any beep codes and there is no change in the diagnostic lights, then it would appear that the motherboard has died.

    The 4700 Service Manual is HERE

    Bev.

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • About jumping the Green wire to one of the Black wires: after jumping the two with a wire, do you reconnect the power cord to the main board with the wire still jumping the two wires? mechanically, wouldn't the jumper cable prevent the power cord from being fitted into the mother board?

    If this previous test fails, then I'm assuming the PSU is not goot. But can a bad PSU turn on the fan? At least the fan is spinning.

     

  • runner_up  

    No, you don't connect the 24-pin connector to the motherboard after installing the Jumper, hence the comment, "reconnect the 24-pin connector to the motherboard", in the following paragraph.

    Yes, the power supply unit fan can still run, even when there is a problem, but it's worth mentioning, the only 100% method of testing a PSU, is to install a know working power supply.

    Bev.

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • Ok, I jumped the green wire to one of the black wires, reconnected the power cable, and pressed the system power switch. Neither the fan nor the HDD runs.  All I hear is a very low-pitch, humming sound from the power.

    Can a good PSU power the fan and the HDD even if it the 24-pin connector is not connected to the mother board?

    Even with the jumper removed from the 24-pin connector, PSU doesn't seem to power the fan or the HDD if the 24-pin connector is not connected to the motherborad.

     

  • runner_up  

    1) Does the Jumper have good metal to metal contact with the 'Black wire' and 'Green wire'  terminals in the 24-pin plastic connector?

    2) No, a jumper is needed for the fan and HHD to run.

    3) That is correct, without the jumper, you need to reconnect the 24-pin connector to the motherboard.

    Bev.

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • 1) Yes, I used a paper clip, so the metal to metal contact was as good as could be.


    Does this mean my power supply has gone bad?

    Can I go to the nearest computer shop and buy any ATX PSU with 300 watts or more to replace it?

  • runner_up  

    Yes, the 4700 has an Mitac case with an open back panel, therefore most standard generic ATX, PSU's, with or without the on/off switch, two SATA power connectors and either a 24-pin or 20+4-pin ATX motherboard connector, can be installed. 

    This can be purchased from most local computer stores.

    Bev.

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • I went out and bought a new PSU.  I chose the cheapest I could find at Microcenter - a $19.95 unit with 400 watts.

    Came home and replaced the old PSU, and voila!  When I turned the power on, everything came back.

    But that's where the happy story ends. Thinking that I solved the problem, I screwed tight the new PSU, put the side cover back on and put the desktop where it belongs.

    I tried to turn back on the power, and the ugly symptom came back.  I jumped the new PSU, and the same result as with my previous PSU: not fan or HDD running.

     

    At least I think I've located the root cause - the PSU.

    But why did my new PSU die just after two minutes? Was it just a bad, cheap PSU? Or could something inside my desktop be causing PSU to fail?

  • runner_up  

    Something does not sound right to me, even a really cheap power supply should last longer than that.

    Sounds like there is a 'short' somewhere, how is the power supply's cord connected?

    Bev.

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • What do you mean by "how is the power supply's cord connected"?

    You mean the DC connector that goes between the PSU and the wall outlet?

    Nothing unusual there.

     

    BTW, with both PSUs, the PC turns on as soon as I connect the power supply's cord to the PSU. I don't even have to press the power button in the front.  Is that a clue to the problem?

    Thanks!

  • runner_up  

    What I meant was, is the power cord connected to a Surge Protector, or a UPS, or directly into the wall outlet.

    "BTW, with both PSUs, the PC turns on as soon as I connect the power supply's cord to the PSU. I don't even have to press the power button in the front.  Is that a clue to the problem?'

    Could mean a bad front I/O panel/switch and/or cable.

    Bev.

     

     

     

    If my answer was helpful, please use the 'Did this answer the question' and click: Yes
    Forum Member since 2001
    I am not employed by Dell

  • Hi Bev,

     

    1. The power cord is conneted to an extension along with other number of electronic appliances.  The extension is connected to the wall outlet.

     

    2. If the front I/O panel, switch or cable is the culprit, would getting a new Dimension 4700 case (as available on eBay) solve the problem?

     

    Thanks.