Print an Expertek Tip: Desktop No Power Troubleshooting

Troubleshooting your desktop that will not turn on.

Another customer woke up again this morning and found that their system won't power on. Hit the switch, no lights, no beeps, no whirr of fans or hard drives. Monitor says "no signal", but from the system? ZILCH. Thus the panic in their voice when I answered the phone.

I'll talk later about how this can happen, as we diagnose the potential issues that we are about to uncover. There are a few things to look at, and consider; specifically how old is the system, was it plugged into a good working surge protector, was it on 24-7?

Something to also be aware of is the fact that, SOMETIMES, when the power supply goes, it can take the Motherboard with it. This is a strong possibility when lightning is involved.

To diagnose this properly, we'll need to open the case, so you'll need a sturdy Phillips screwdriver and a standard AT power supply tester. If you have a spare "known-good" power supply to swap into the unit, that will help confirm your findings.

WARNING: DO NOT OPEN THE CASE OF THE POWER SUPPLY ITSELF. HIGH VOLTAGE AC POWER CAN SHOCK AND KILL YOU. The wires that come out of the power supply are low voltage DC, and if you are moderately careful, you can avoid injury.

With the power cord disconnected from the power supply,
Open the case and Check the Capacitors on the motherboard, are any swollen, split, or leaking? (possible heat related motherboard issue, if this PC is old, may wish to consider a new system ASAP)
Remove both the 20/24 pin main and the 4-pin 12v power cable connectors from the motherboard.
Attach the cables to the power tester,
Plug AC into the supply (and hit the switch on the tester, if there is one). Check the lights, all lighting up (perhaps excepting the -5v)??
If so, then the Power Supply may not be the issue, perhaps it is a bad switch or a bad motherboard. Plug the original PS back into the MB and try one more time. (If this works, it may have been a fluke or corrosion on the connectors)
Does the switch seem to click ok? (If No, replace it)
If it's still not coming on, Will the MB start with a different power supply? (If Yes, Replace it)
If putting a different power supply on the system doesn't fix it, then lastly, you can simplify the problem by stripping the motherboard down, removing all cards and drive cable connections from the motherboard (ram sticks, modems, Sound cards, SATA or IDE connections) and try it one last time. If you don't get a set of fast beeps from the system at this point then it appears that the board is dead. Data recovery may still be possible, but it is time to consider repair or retail.

ALL Power Supplies die eventually due to heat. The heat gets worse in dusty environments, and without regular maintenance, may only last a year or two. Blowing them out and making sure the fans spins freely is the best thing you can do, basically every 3-6 months.

Another thing that shortens the life of your power supply is unfiltered input. Specifically, if you have a super clean AC input, it's going to make the electronics work a lot more smoothly. Use of a quality surge protector, or even better, a battery-backup, will give you the best protection and longest life.

It is my unfortunate duty to tell you that occasionally we get a customer in whose power supply died on the way to the shop. It was working okay when they left home and didn't like the trip, bumping along in the car. It has also been my experience that older system will sometimes die, just being moved across the room. When we look into the power supply case, I have found that invariably, it was severely choked with dust, and there are several failed components inside. Lastly, sometimes, when a power supply dies, it takes the motherboard with it, as it shorts out. It is not uncommon to see both Power supply and motherboard non-functional, and yet, the hard drive can still have data recovered from it.