elromi
Not applicable

Dimension 5100 won't power up

The computer will not power up after a proper shut-down:

  • Front panel ON/OFF button/switch is not illuminated and does not initiate power ON 
  • NO diagnostic lights or beeps available 
  • Green light on MB is solid ON

Checked front panel I/O card:

  • ON/OFF switch actuates and makes contact all the way to the ribbon connector @ pin 11 (or 21 depending on counting scheme) relative to any ground/common pin [e.g. 17 (or 33)]

 

 

 

 

Pin 1

Pin 40

 

 

 

 

Pin 11

Switch

Key

 

 

 

 

Pin 1

Pin 40

 

 

 

 

Pin 11

Switch

Key

Checked voltages on MB 24-pin PSU connector:

  • Pin 9, VSB, at 5V
  • Pin 16, PS_ON, at ~4V - no change when pressing ON/OFF switch, or when shorting pin 11 of ribbon cable to gnd
  • Pin 8, Power_OK, at ~0v - no change when shorting PS_ON to gnd

Question before spending money - Is it PSU or MB?

Thanks in advance

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8 Replies
shesagordie
9 Rhodium

Re: Dimension 5100 won't power up

elromi

As the power button LED and none of the diagnostic lights are lite and there are no 'beeps', suspect power supply failure, try installing a different PSU, as a 'know' working power supply is needed to check the motherboard.

The 5100 does not use a Dell proprietary power supply, most standard ATX power supplies with either a 24-pin or 20+4-pin main motherboard power connector, with, or without, the on/off switch can be used, a power supply with two SATA power connectors is needed.

You should be able to buy a replacement power supply from a local or online computer store.

The instructions for replacing the power supply are HERE.

Bev.

 


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pastric
2 Bronze

Re: Dimension 5100 won't power up

I have the same problem on a Dimension 2400. Replaced the power supply but it did not fix the problem. Could the power switch be bad? If the green LED on the motherboard is on, does that mean it is good? If not the power supply or the motherboard, then what? :emotion-42:

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shesagordie
9 Rhodium

Re: Dimension 5100 won't power up

pastric

Are any of the four Diagnostic lights on the back panel lite, are there any 'Beeps'?

The Dimension 2400 Troubleshooter and Diagnostic Guide, is HERE

<ADMIN NOTE: Broken link has been removed from this post by Dell>

 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 20-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 20-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/or there is no change in the diagnostic lights, then it would appear that the motherboard has died.

Bev.

 


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greenblob
2 Bronze

Re: Dimension 5100 won't power up

HI,

I have no hard drive installed in my machine at the moment, which is not the problem. My machine would not power up AT ALL previously, the only signs of life were: i) the power button blinked (orange) every 6 seconds or so. ii) The SD card port LED flashed green subsequently. iii) The Green motherboard light was on permanently. No fans or any other lights were on.

I believe this was because of a short, as one of the Front USB ports was completely mashed up, and many pins were connecting, it is beyond repair. I've disconnected the front panel cable through the motherboard.

This resulted in the fans working, and all parts attempting to work, but obviously no lights on the front panel as it is un-plugged. I hear 2 short beeps followed by 1 long beep when I give the PC power.

Does anybody have any idea what my problem is or how to fix it please?

Thanks in advance, Luke

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fjparedes
2 Bronze

RE: Dimension 5100 won't power up

Hello, I am having the same problem. I tried all of the above to no avail. I too have a USB port that's all mashed up. I am ordering the USB/Audio Panel for the Dimension 5100. I think this is what's causing it not to turn on. Good luck!
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shesagordie
9 Rhodium

RE: Dimension 5100 won't power up

Hello, I am having the same problem. I tried all of the above to no avail. I too have a USB port that's all mashed up. I am ordering the USB/Audio Panel for the Dimension 5100. I think this is what's causing it not to turn on. Good luck!

 
fjparedes
 
Yes, that is possible and is caused by the USB port's contacts shorting out.
 
Bev.

 


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Forum Member since 2001
I am not employed by Dell

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surman
2 Bronze

RE: Dimension 5100 won't power up

I had the same problem. No power what so ever and green light on motherboard. Upon plugguing the power supply into the power supply tester I found out that +12volt was missing, PSu was only producing -12volt.  I replaced the power supply and the computer started working again. Thats the simple part. The hard part is selecting the right power supply. If you going with original dell PSU you are fine however make sure it is really Demension 5100 power supply with power outlet on the bottom. I have discovered that many claim to have the right power supply but dont. If you decide to get a non dell power supply, you can but not every power supply will fit. You have to make that there is atleast .5" clearence between the top edge of the PSU and the top edge of the power outlet. The PSUs that have the power outlet with triangular "wings" wont fit. Some of the newer PSUs with mesh body and 120mm fan may fit. I used Inland Gold series ILG-400-2 power supply from microcenter. You may use any other as long as the power outlet is far enough from the edge. Also, the power supply tester is a good tool to have at home. You could have tested your PSU in less then 30 sec. flat.

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lgrande717
2 Bronze

RE: Dimension 5100 won't power up

Hi, My dell dimension 5100 seemed to have the same problem but in further inspection it turned out to be that the actual power button does not make contact to the usb/headphone/mic hub that has the "real" power on/off button. What i think the problem is, the actual hub or housing seems to move further back and the button in front of case feels stuck and wont power up the tower. I checked inside and it appears to have a single screw but, the darn thing still shifts backwards! The temporary fix is to poke the the actual button by cutting a whole a little bit above the panel power button. I want to know if there is a way to fix this issue!

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