So, we have an old HP desktop that we never really use anymore. One reason is because it actually stopped working a year or so ago. My initial diagnosis was that the power supply was bad because the machine wouldn't power up.
I finally got around to taking it apart and pulling the power supply out this weekend. It is a 20 pin motherboard connector instead of a 24 pin. I shorted the power on pin with a ground pin with a paper clip per instructions found online, and the cooling fan does indeed turn on when I plug the power supply in. It has a built in LED that lets you know that it is powered on, and it stayed steady green.
Then I took my multimeter and started checking each pin's voltage based on a 5% tolerance table (again, based on online instructions.) Everything is within range except pin #10, the yellow wire. It should read within 5% range of 12 VDC, and I can only get 11.1 V out of it. Do you think that is my problem? Can .2 of a V make that much of a difference and cause the machine not to power up when everything is connected? Would only one pin short out like that at a time?
I'm no PC or electronics expert by any means, but I thought maybe someone here might be able to help.
I hate to spend the $30 or so on a new power supply if that isn't my problem, because I don't think power supplies are returnable.
I'd love to get the machine back up and running to get my 4 year old started on navigating his way around a PC, and I'd love to be able to get some old files off the hard drive. I've also pulled the hard drive out in case I need to use a cable or HD dock to pull the data off, but it'd be nice to get the machine going anyway.
Thanks in advance!
Call some local PC shops and see if they will hook up a powersupply for free to test your system. When I was actively upgrading parts every few years, I would keep a cheap power supply just to power-on systems. Not for use, just to test with. But the days of free after rebate power supplies is long gone.