Jump to content


 


Register a free account to unlock additional features at BleepingComputer.com
Welcome to BleepingComputer, a free community where people like yourself come together to discuss and learn how to use their computers. Using the site is easy and fun. As a guest, you can browse and view the various discussions in the forums, but can not create a new topic or reply to an existing one unless you are logged in. Other benefits of registering an account are subscribing to topics and forums, creating a blog, and having no ads shown anywhere on the site.


Click here to Register a free account now! or read our Welcome Guide to learn how to use this site.

Photo

No power reaching PC


  • Please log in to reply
6 replies to this topic

#1 wish2learn

wish2learn

  • Members
  • 72 posts
  • OFFLINE
  •  
  • Local time:11:13 PM

Posted 20 February 2009 - 08:12 AM

Hi, I'm not entirely sure this is a hardware problem but perhaps you may have some insights here....

What was once only a very intermittent occurrence has now become annoyingly regular. It seems I have no power coming through to start up my computer.
After being turned off for the night, the next morning it will not start up again.

Its as if there is no power getting through as nothing responds to pressing of the switch. I have a surge protector plug from which everything to do with computer (and a desk lamp) emanates - and all these including the monitor show lights to indicate they have power reaching them, but the computer itself will not respond.

Usually this goes on for hours, and I unplug and replug everything. Sometimes this works, but lately not. Today I tried plugging the computer directly into the wall (minus surge protector) to no avail. I also tried plugging the computer into another plug point in the house, but no luck there.
Finally I carried the computer off to a computer shop (I brought along my cable too just in case). I was thinking it may be the switch or even the power supply, but the computer fired up into action each and every time in the shop without a problem. The technician also checked my cable and found no problem.
He said that if it were my power supply that this would be a consistent problem and that the computer would likewise not start up...

I took my computer home, and replugged everything in again. Same problem. Computer will not start up. Then randomly after having pressed and re-pressed the switch I give up and go away. Then about 1/2 hr later I walk past the study and hear the fan going and see the computer has in the meantime found the power to 'switch itself on'.

Nobody I know understands how it could be
1) right-as-rain in the computer shop, but not working at home
2) be able to start itself up sometime after I pressed the switch

P.S: I have Windows XP, and once the computer has fired up then everything runs very nicely indeed. I just cant switch off or even put it on stand by. I like to be able to put the computer on standby when I go out but now if I attempt to do so it makes starting up again much worse than ever :thumbsup:

All insights to this strange problem gratefully received...

Edited by wish2learn, 20 February 2009 - 08:18 AM.


BC AdBot (Login to Remove)

 


#2 hamluis

hamluis

    Moderator


  • Moderator
  • 55,244 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Killeen, TX
  • Local time:04:13 PM

Posted 20 February 2009 - 11:22 AM

If it runs properly at other locations...my guess is location, location, location...not the system.

Louis

#3 Wildabeast

Wildabeast

    Bleeping Lurker...


  • Members
  • 1,253 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Nebraska, USA
  • Local time:04:13 PM

Posted 20 February 2009 - 11:37 AM

I had this problem once, years ago, it was the power cord. I didn't believe it when they told me, but it was true. Inside the cord, the contacts, on the female end, have springy contacts and if one of them gets to sticking like mine did then your power is only intermitant. (spellng?) Try replacing the power cord and see if that helps... :thumbsup:
"The nine most feared words in the english language, 'I'm from the government, and I'm here to help'..."
Ronald Reagan

#4 dc3

dc3

    Bleeping Treehugger


  • Members
  • 30,265 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Sierra Foothills of Northern Ca.
  • Local time:02:13 PM

Posted 20 February 2009 - 11:46 AM

Just checking here, there are no fans or LEDs on the computer coming on when this happens?

This still could be a power supply problem, or a motherboard, or the power switch, if the computer is getting power and there is no interruption of the AC house line voltage. You can test the power supply with the procedure outlined below. This may not be something that you are comfortable with doing, if this is the case then don't try it. There are two other things that you can try, but both of these will involve working inside the case. You can use a Ohm meter to test the switch, this is a momentary switch which means that as long as you hold the switch button down the contacts will be closed. The other is to pull the two wires from the power supply from the motherboard and use a screwdriver to very briefly short out the two posts that the switch plugs into, this serves the same function as the switch.



The purpose of this procedure is to bypass the motherboard to test the PSU.

Caution:
This procedure will involve working with live 12VDC electrical potentials which if handled improperly may lead to electrical shock. Proper precautions should also be taken to prevent electrostatic discharges (ESDs) within the case of the computer. For safety purposes please follow the instructions step by step.

First, shutdown your computer. Then unplug the power cable going into your computer.

Once you have opened the case, touch the metal of the case to discharge any static electricity.

The connector of the PSU which connects to the motherboard is readily recognizable by the number of wires in the bundle. To disconnect it you will need to press on the plastic clip to disengage it and then pull the connector up and away from the motherboard. Please take notice of the location of the locking tab and the notch on the socket of the motherboard, this will only connect one way as it is keyed. This wire bundle will have a memory of the way it has been installed and will want to bend back that direction, you may have to play around with it to find a position that the connector will stay in the same position while you run the test.

Posted Image

From the top left to right the pins are 13-24, the bottom from left to right are 1-12.


Please notice that there are PSUs with 24 pin and 20 pin connectors, the location of the green wire in the 24 pin connector is #16, and the green wire in the 20 pin connector is #14. If you look at the connector with socket side facing you and the clip on the top the number one pin will be on the bottom left corner. This makes the pin out for the 24 pin connector from left to right 13-24 on top, and 1-12 on the bottom. The pin out for the 20 pin connector from left to right is 11-20 on top , and 1-10 on the bottom. If you look at the connectors you notice that these are sockets that fit over the pins on the motherboard where the PSU cable attaches, this is where you will place the jumper. For a jumper you will need a piece of solid wire about the size of a paper clip (20-22 awg), preferably a wire with insulation. It will need to be large enough to fit firmly into the socket so that it will not need to be held in place while testing. You are at risk of electrical shock if you are holding the jumper when you power up the PSU. Insert one end of the jumper into the socket of the Green wire, and insert the other end into the socket of any Black wire.

Once the jumper is in place plug the cord back in. If the PSU is working properly the case fans, optical drives, hdds, and LEDs should power up and remain on. I would suggest that you not leave this connected any longer than is necessary for safety purposes.

At this point you can use a DC Voltage meter to read the different rail Voltages. You will want to insert the black probe into any of the Black (-) sockets, and insert the Red (+) probe in the five different colored sockets, one at a time. Below are the five different colors and their corresponding rail voltages. The Voltages should be within about ten percent plus or minus of the given values.

Yellow +12VDC

Blue -12VDC

Red +5VDC

White -5VDC

Orange +3.3VDC

To reconnect the 20/4 pin connector unplug the power cord, remove the jumper, and reconnect the connector. Take a moment at this time to make sure that nothing has been dislodged inside the case.

Family and loved ones will always be a priority in my daily life.  You never know when one will leave you.

 

 

 

 


#5 wish2learn

wish2learn
  • Topic Starter

  • Members
  • 72 posts
  • OFFLINE
  •  
  • Local time:11:13 PM

Posted 20 February 2009 - 02:54 PM

Thanks so much for these helpful replies...
I shall start with a replacement cable and move on from there if necessary. Lots to go on from dc3 - perhaps a tad beyoond my capabilities, but still good to know about so thanks.

#6 fairjoeblue

fairjoeblue

  • Members
  • 1,594 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:USA
  • Local time:04:13 PM

Posted 20 February 2009 - 03:13 PM

"I have a surge protector plug from which everything to do with computer (and a desk lamp) emanates "

If the lamp works consistantly with no problem try switching it with the computer on the surge protector.
OCZ StealthXstream 700W,Gigabyte GA-EP45-UD3R , E8500, Arctic Freezer Pro 7, 3GB G.Skill PC8500,Gigabyte Radeon HD 4850 OC [1GB ], Seagate 250GB SATA II X2 in RAID 0, Samsung SATA DVD burner.

#7 wish2learn

wish2learn
  • Topic Starter

  • Members
  • 72 posts
  • OFFLINE
  •  
  • Local time:11:13 PM

Posted 21 February 2009 - 08:37 AM

"I have a surge protector plug from which everything to do with computer (and a desk lamp) emanates "

If the lamp works consistantly with no problem try switching it with the computer on the surge protector.


Thanks, everything is plugged into a bank that plugs into the surge protector. I tried plugging the computer directly into the wall minus surge protector to no avail.
A great deal of info on the Web argues that it is better to leave the computer running 24/7 - as this is less stressful for the computer parts that start-ups every day so maybe this could be a solution.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users