I have an eMachines PC (my 9-year-old uses it) that won’t power on. It’s a few years old. We just got back from a one-week vacation. I don’t remember if we left it powered on before leaving but our flashing clocks indicate there was a power failure while we were gone. The computer is plugged into a surge protector.
If there is any type of hardware problem at all it is not worth fixing but I am wondering if there could be something simple, like an internal fuse.
I have a multimeter but haven’t tested anything in the computer yet; if there is voltage coming into the power supply but not out, does that mean I have a bad power supply? Are there any dangers in performing power tests on a computer if you are intelligent but not trained for it? (I have done a fair amount of household wiring that is compliant with code, so I’m not stupid about electricity; I have replaced hard drives and memory so I’m not stupid about computers; but this seems to be a slightly different animal.)
This might sound stupit, but with my computer if it loses power due to a power outage, no matter how long I leave it off for afterwards, it has to be unplugged for like 10 minutes and then it’ll power right up. It’s strange, it took me a loooong time to figure it out*, but it works.
*Normally I was in the same place as you, confused, trying to figure out what, exactly, to test. At some point I would give up and come back a little later and it would work just fine.
Oh, as long as you got that multimeter, test the obvious, power at the outlet, power at the computer end of the cord. You could pull the big plugs out of the motherboard, ground one end of the multimeter and check to make sure some of the pins are getting voltage (make sure your MM is set fairly sensitive since it’s low voltage, and set to DC).
ETA, plug a lamp or something into that surge protector, make sure it’s good.
Most power supplies won’t be supplying any voltage to the plugs if they’re not plugged in to the motherboard, because most power supplies aren’t turned on by the switch on the back of the case. It’s easy enough to trick them, though.
Note: this all assumes the psu is an atx unit. If it’s some other standard, google up the relevant pinouts.
Unplug the motherboard from the psu. That’s the big 20/24 pin plug, and possibly a small 4 pin plug nearby. Leave the hard drives etc plugged in to provide a load. Now, with the psu plugged in and the little switch on the back on, short the green pin on the 20 pin plug to any of the blacks. (ATX plug pinouts, note the green wire is “power supply on” and is what the motherboard ordinarily shorts to power things up) If nothing comes on, your power supply is bad. If things do spin up, you can check the voltages with your multimeter to see if they’re where they should be. So long as you don’t short the 5v or 12v lines to ground or to each other, there’s no particular danger.
As I couldn’t remember if there are accessible fuses inside PSUs, I just cracked one open, and the fuse is soldered directly to the main board instead of in a socket, so you’d have a bit of work replacing one. If you crack the case on a PSU, keep in mind that the big caps on the main board can store significant voltages for extended periods of time. If you don’t know how to deal with that, I wouldn’t recommend trying.
eMachines have notoriously bad power supplies [A few examples]…I wouldn’t be surprised if yours died because of a power failure. If the machine was left on, I’d almost bet on it.
My aunt got one of those buggers for my cousin when he was a tot, and he did a lot of hard shut-downs which caused the power supply to blow. She got a new box thanks to the warranty she got, and it happened again. The thing has been running fine (for an eMachine) since then, about 5 years now.
Seconded. Removing a power supply is a very simple task, pop that thing out and cart it down to the neighborhood computer shop. Everyone has power supply testers, takes about 30 sec to figure out if the PSU is hosed. Many shops carry the testers as well for $10-$15. If its dead, IME about 60% of the time all it needs is a new power supply unfortunately the other 40% or so it takes something else with it.
Thirded. eMachines has used cheaply built power supplies that are run to within a couple watts of overload on a regular basis for quite a few years. In other words, they’re crummy to begin with, and run hard, so failures are very common.
Fortunately, replacement power supplies are pretty cheap these days.
Oh come now. The plugs coming off a power supply only fit where they’re supposed to go, and in the correct orientation. They’re completely idiotproof. Now, you could quite easily miss a couple critical ones when you plug things back in, but there isn’t really a wrong way to plug things in. If the plug fits, it’s the right one. All those four-pin molex are interchangeable and wired in parallel.
I don’t know if you’ve ever looked inside an eMachine, but the board and all the other components appear to be wired to accept about fifty different types of connectors, some of which look a lot like power supply sockets.
I tried to help a friend install a new power supply in one and we ended up plugging one of the connectors into what I think was a connector for a FireWire port.
Sadly only true for ATX power supplies. The older AT standard had two identical plugs that fit side by side into the motherboard - except that if you got them the wrong way round you fried the board and everything attached to it, because you’d be putting +12V where the board expects -5V. I learned this the hard way (fortunately on a nearly-dead 386, so it wasn’t much of a problem).