Got new PSU but PC still dead

corblimey

My self build PC died last week (we had a short sharp lightning storm in the area which is what I think killed it) and I finally got a replacement PSU, but after connecting it all up this evening, there's still no sign of life on my motherboard or PCI card. I'm guessing the mb is fried, although from what I can see, the capacitors look fine. I can detect a slight hum from the new PSU, but the fans don't spin (I've googled and I believe that's fine, they'll only spin up if needed) so I can't see that as the problem.

I'm about ready to throw in the towel on self builds and tootle off to PC World, is there anyone close to Cork city fancy having a look at it/buying it off me before the weekend?

BloodBath

It's hardly the fact it was self built that was the problem. Any electrical device is vulnerable to damage in a lighting storm. You should protect the expensive ones with surge protectors that cost nothing these days.

corblimey

Yea I'm not a complete idiot, everything is plugged into a surge protector. It's not a fancy one with a guarantee, but it claims to protect from surges. There are 2 monitors and a PS3 plugged into the same brick and they still work fine, so I'm not absolutely convinced that the lightning storm was the cause - it may just be a coincidence.

Update? I swapped the power cord, and this time when I turned on the PSU, the green light on the GPU came on very briefly and went out again. And nothing since. Does that help?

BloodBath

I wasn't saying you were. Are you sure the fuses aren't gone on the surge protector? Did you try it in different plugs?

westom

corblimey wrote: »

... everything is plugged into a surge protector. It's not a fancy one with a guarantee, but it claims to protect from surges.

First, now learn some facts about that protector. When too close to appliances and too far from earth ground, then it can provide a surge with even more destructive paths through an appliance. Your supply already had superior protection. But an adjacent protector can simply bypass that protection; connect a surge directly into the motherboard.

That protector only claims to protect from a type of surge often made irrelevant by protection already inside a supply. It does not claim to protect from another type of surge that typically does damage. Read its spec numbers.

Second, observation almost never identified a defect. You replaced a supply only on speculation. Also called shotgunning. Better is to learn how to identify a defective part before even disconnecting one wire. That means using a multimeter to measure voltages on six wires. Then each of many components in a power 'system' can be identified or exonerated. Finding the defect before replacing anything means about one minute of labor, directions, and numbers from a meter. Then others who better know this stuff can tell you things about that system that you never knew - as well as identify the defect.

corblimey

BloodBath wrote: »

I wasn't saying you were. Are you sure the fuses aren't gone on the surge protector? Did you try it in different plugs?

Cheers, but I've tried the PC power cord in a monitor that continues to work, and the monitor power cord in the PC and it still fails, so there doesn't appear to be anything wrong with the plug or cords.

westom wrote: »

Second, observation almost never identified a defect. You replaced a supply only on speculation. Also called shotgunning. Better is to learn how to identify a defective part before even disconnecting one wire. That means using a multimeter to measure voltages on six wires. Then each of many components in a power 'system' can be identified or exonerated. Finding the defect before replacing anything means about one minute of labor, directions, and numbers from a meter. Then others who better know this stuff can tell you things about that system that you never knew - as well as identify the defect.

The PSU was definitely dead, even if nothing physical happens, you can still detect a soft drone in a working PSU when plugged in, this was not happening with the old PSU. And is happening with the new PSU. Yes, there are things I can do to make sure that power is getting across, but I wouldn't say I replaced the part on speculation, it was proven to be inoperative.

westom

corblimey wrote: »

The PSU was definitely dead, even if nothing physical happens, you can still detect a soft drone in a working PSU when plugged in, this was not happening with the old PSU.

I have never heard a PSU make any sounds when 'powered off'. PSU does not determine when to power on or off. A power controller does that. Another part of the power system that says when a PSU can consume power. And does other things such as determine when CPU is allowed to operate.

Also important and useful is to know which part (subsystem) of that PSU has failed. Meter will also report that in numbers. Knowing specifically what failed then says what or where is any other defect might be located.

You are having confusion because a part was replaced without first getting facts (shotgunning). With numbers from six wires, a next post could identify each exonerated or suspect defective part. Two strategies exist. When using a the shotgun method, then valuable facts are lost.