Well heck...

[feren]

We stepped out of the apartment today around 5pm, almost as soon as Kestral got home, so that we could go up to BD's for dinner. The meal was enjoyable, and afterwards we stopped at CompUSA and Circuit City so that I could try to chase down a USB flash drive for myself (and possibly one for Roho) so that we could tote our MP3 collections to work in a convenient manner. We came home from our evening excusion around 9:30, and when we got into the apartment I thought it sounded awfully quiet. I poked my head into my bedroom and sure enough, my PC was off. This wasn't really a big deal to me, although it wasn't something I expected.

I poked the power switch thinking it had just gotten bumped by Ra during our absence... and nothing happened. I checked the power strip, since Ra has been known to step on that and turn the switch off.... nope, that's still fully operational, and my monitor and speakers are on, so it's not like the strip is lying to me or has a blown fuse. I plug the computer directly into the wall and throw the switch -- nothing. I look inside the case and the LED on the motherboard that's supposed to glow to indicate power from the power supply isn't glowing. I pull the machine apart, check for loose connections, nothing seems to be awry here except for the small fact that my PC will not turn on.

The way I see it either the mobo is shot or the power supply is shot, or possibly even both. The only way for me to test and see where the actual problem lies is to get a new power supply tomorrow and install it -- if the machine doesn't boot than it's very likely the mobo is shot.

I'd like to take a moment to say that it's just this sort of uncertainty and inability to allow user troubleshooting that makes me HATE the ATX system that is so prevalent in PCs today. In the old days you could tell if the power supply was shot because the power switch was wired directly in. If you pressed the switch and the fans didn't whir into life then the supply was gone. If they did and the system didn't boot it was probably something else (mobo, RAM, controller cards, etc). You could also clip a multitester to the power switch's leads and see if there was voltage on the line, another sign if the capacitors and internal guts of the supply was working as designed. With the ATX system you can't do that... or if you can, nobody has shown me how and it's not nearly as straightfoward. I've said it before, I'll say it again: the power supply should not be controlled by the motherboard! No, no, no! This is ++ungood design, stop doing it!

The part that tweaks me the most is I can't even troubleshoot it because I:

Lack a multimeter

Lack sufficient documentation about the ATX power supply design, so even if I had a multimeter I wouldn't know what leads to clip on to for voltage/amperage testing. I'm sure if the specs were just AVAILABLE I could do it with at least a light probe.

Ahem.

I really hope it's the power supply because that's cheap and easy to handle. Mobos are cheap as well these days but are a little more annoying to replace, and it's not a battle I want to fight unless absolutely necessary. Harumph. Oh well, this will give me something to work on tomorrow while everyone else is out of the apartment attending the MFF staff meeting.

Comments

[youngvanwinkle.livejournal.com]

How to test an ATX power supply.

I'll try digging up some more stuff for you but this is a start.

[feren.livejournal.com]

Two words: You rock.

Off to True Value I go to grab a multimeter. I hope they carry Fluke. :p

[youngvanwinkle.livejournal.com]

A bit more:

PDF of the ATX spec

Short and to the point: "Wiring of the ATX power supply". From it:

While we're at it, you can power up an ATX power supply by shorting the green wire with any black ground wire. As you know, the ATX power supply will not turn on normally without a motherboard connected to it. There are times when you may want to test an ATX power supply or use the voltage from one but don't really want to hook up a motherboard. There's only one green wire and there are plenty of ground wires so it's easy to do. To use a bent paper clip and insert one end in the green wire connector and bend it around and put it into a black wire connector.

That would allow you to turn on the ATX power supply without it being connected to the motherboard, so you can test and see if the power supply is good. Or you can read all the other shit and make sure it's the right way to do it.

And also:

Some other shit that reads like it might be useful

[yakko.livejournal.com]

You really want to have a load on the power supply when you run it standalone. There's a "power supply tester" being sold which consists of a big resistor for load and an LED, and may have contacts to allow the supply to be powered up without a mainboard.

If not, short the wires as described.

If you fail to load the power supply, you're looking at "KABLAMMO!" from the power transistors as the current builds up... not good

[feren.livejournal.com]

Hmm. I imagine the resistor/LED combo would just be part of the circuit used to short between that green lead and ground, yes?

[hightensile.livejournal.com]

One LED in line with the resistor(ACTIVE), one calibrated to the proper voltage read-out(OK), another for any read out(NOT OK). If you wanted to get fancy, you could put in LED's for 5v and 12v output as well. Jeesh, and they charge $20?

--kit