Jump to content

Welcome to Geeks to Go - Register now for FREE

Geeks To Go is a helpful hub, where thousands of volunteer geeks quickly serve friendly answers and support. Check out the forums and get free advice from the experts. Register now to gain access to all of our features, it's FREE and only takes one minute. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more.

Create Account How it Works
Photo

Real Mystery


  • Please log in to reply

#1
RobertJ.

RobertJ.

    New Member

  • Member
  • Pip
  • 5 posts
I have a Dell PC running Win 7. My computer's on off switch was not working so, I bought another, a week later this power switch failed as well. I left the computer alone for a couple of weeks, today I again tried to start the computer, no luck. I then removed the power switch and the computer started, with no switch! I am on that computer now. Can anyone please tell me what is going on, and how i might find an answer for this strange happening?
Would really appreciate your help.


Bob
  • 0

Advertisements


#2
Macboatmaster

Macboatmaster

    7k

  • Member
  • PipPipPipPipPipPipPipPip
  • 7,237 posts
Well my first thought is that it was NEVER the switch. Presuming that you mean the on/off button on the front of the case.
That is only a contact switch, it simply shorts out two pins on the motherboard header
See this
The power switch on the front of the case is just a momentary contact switch. The motherboard always has a little bit of power, and pushing the contact switch simply completes a circuit between two little prongs on the motherboard that signals the power supply to start supplying full juice to the system. When you open the case and trace the wires from the backside of the on/off switch down to the motherboard, you can pull the those two wires off the motherboard and touch the two prongs with a small screw driver (be careful poking around - touch only the two prongs that were underneath the wires from the switch). The system should come to life. If so, then the switch is bad, it's not making the momentary contact to complete the circuit as it should..

If you still have the old power button, connect a multimeter on a resistance reading, or a continuity if the meter has that - the switch does not have to be connected to anything and which way round you connect the meter leads does not matter. Work the switch. If you are on resistance if the meter is digital 1 is open circuit and when you hold it in 000 or close to it depending on the scale is closed circuit.

Further to the foregoing, it may and I stress MAY be either a PSU transient defect or far worse a motherboard issue.
Please DO NOT think that I am saying it is, but I strongly suspect it is NOT the switch.

If the power to the computer is connected via an anti-surge bar it is worthwhile trying a straight connection to a power outlet.
I have known the anti-surge bars with a transient defect

Edited by Macboatmaster, 23 September 2011 - 11:24 AM.

  • 0






Similar Topics

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

As Featured On:

Microsoft Yahoo BBC MSN PC Magazine Washington Post HP