Question about System Power Supplies

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Replacement Power Supply Doesn't Work

The front light of my desktop computer blinks red every 2 seconds and the computer won't power up. On the advise of a local computer tech, I replaced the power supply with a new one direct from HP Compaq but the computer still won't power up and I still get the blinking red light. What else could be causing the computer not to work? Please help. Thx.


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Re: Replacement Power Supply Doesn't Work

Hi. The first thing you should always check is that all of the wires and connectors are in good shape, making contact where they should, and not shorting out anywhere. I know this sounds simplistic but the way these things are assembled these days with the wires just barely long enough to get to their destination they can pull apart, wear if there is vibration (causing shorts), or even pull or lift solder joints off of the circuit boards. You can test to see if the PSU needs to be connected to the motherboard at the ATX connector by plugging the PSU in and trying to turn it on without being connected to the board. I have found that the PSU generally must be connected to the motherboard in order to work. There was one I had worked on a long time ago that didn't require to be plugged into the motherboard, I think it was a Pentium 2 and it was a very long time ago. Your PSU probably does need to be connected.
If you have a battery backup, Uninterruptable power supply connected, disconnect it. You may well have a bad UPS. Even if you disconnect the UPS and test the voltages it doesn't matter as what you are measuring is not under load. I have seen a bad UPS prevent a computer from working and when it was disconnected the computer was fine. However, if a bad UPS remains connected too long and the computer suffers BSOD or crashes often they can ruin the motherboard.
Well I hope this helps you. It is a decent way to begin to troubleshoot many PSU problems. One other thing, don't forget to use your nose. You can often smell burnt components. If you smell fowl burnt plastickind of oder then try to locate where it is strongest and then look for signs of heat or fire, like blackened circuit board, wire, or components. Good luck. Greg

Posted on Feb 15, 2009

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Re: Replacement Power Supply Doesn't Work

Bad ram, bad motherboard, bad video card, could be any one of a number of things.

Posted on Dec 15, 2007

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