# PC won't turn on: green flashing light in the back



## unicorncove

We just got a Compaq Presario S6500NX from a friend and it won't boot up. It won't even turn on! 

When plugged in, the little green light in the back flashes and no amount of pressing the power button makes any difference. 

The machine worked when it left his house, just not when it got to us.

What is the problem and how do we fix it?


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## cwwozniak

Are you referring to the green light next to an Ethernet port or some other light? If it is an Ethernet port light do you have the port connected to anything?

It might be a simple matter of a connector on a cable bewteen the power button and the motherboard working loose in transit. Opening the case and reseating all connectors between the power button and motherboard may solve the problem.


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## unicorncove

Nope. Tried that. Same thing. Information elsewhere says it's probably that the power supply needs to be replaced. Not sure why that would have happened en route to us though...


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## cwwozniak

unicorncove said:


> Not sure why that would have happened en route to us though...


Maybe the power supply was licensed from Compaq for use only by the original owner and it sensed it was getting a new owner. 

On a more serious note, the supply could have had a poor internal solder connection or other workmanship issue waiting for a bit of shock or vibration to actually fail.


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## Courtneyc

Also, since this is a Compaq (now HP), try this:

Unplug the cord from the PC and whack it on a hard surface, like the floor, a couple of times. Then plug it in. 

For some reason, this has worked on several Compaq desktop machines at my job. I'd be at a complete loss to know why.

Courtney


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## Jazzgirl

The laugh is for the computer sensing it had a new owner.


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## unicorncove

(just dredged up the computer again, hence, reopening an old post)

The blinking light is on the power supply. In the back of the computer, where the power cord plugs in, next to the fan. There is also a little red switch which is on 115 but can be slid over to 230 (the same switch on the Compaq Presario 6000 currently online with is on 115). When the cord is plugged into the machine and into a socket, the light automatically comes on, and stays on for a few minutes after unplugged. On this nonworking machine, however, the light blinks rapidly instead, and makes a clicking sound. 

Interestingly, a few minutes ago I plugged in the machine by itself (after bringing up from downstairs) and it powered up, the fan turned on, everything! So I opened it up and cleaned out some of the dust and, lo and behold, when I tried to turn it on again with the monitor and accessories plugged in, I got the blinking/clicking green light and no power up. 

This leads me to believe that something isn't connected properly, however, when I did a cursory check inside nothing seemed loose. I don't dare do anything to the power supply though, until I know what I'm doing. 

As this computer is a better model than my current one, would it be possible to switch out the power supply of my working computer with that one? They're both Compaq Presarios...


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