Recently [the last few days] my computer has been freaking out. Sudden restarts, the USB ports all lose power at once, and so on. Well, I think I might have found the cause of the problem (images attached).

Give it to me straight, doc. What's the prognosis?

pixies with brown paint...

That seems to be pins 4, 6, 21, and 22, which are all +5V pins. I'd check the power supply to see if it's providing that power properly. Of course, since it's ATX, you really need a special tool to do that (since you have to send it a signal to turn on at all).

I don't remember what +5V powers in a computer, though, so I'm not much help there. My guess is that it's your power supply that's the problem though. But I could easily be wrong.

Well, it turns out that turning it on isn't that hard.

USB uses 5v, along with drives for the communication bits.

Looks like you've got an intermittent short between 5V and chassis ground. (Plus a power supply that doesn't shut down the 5V rail even when a dangerous current is flowing down it.)

Where the short is (somewhere on your motherboard, or on something powered via your motherboard, perhaps USB or a fan), you should see similar overheating damage to that on your power connector. It probably also smells faintly of smoke. Your computer is a fire risk until you find and fix the short.

You're relatively lucky: I had a PC once short 5V to 12V, which had the effect of blowing the motherboard, the CPU, all the expansion cards, all the hard drives, the CDROM, and the tapestreamer. Fortunately the PSU shut down before anything caught fire, or even got as blackened as your connector.

Peter

Now that is an expensive toaster!

For the sake of my various USB devices, I'm going to ditch the machine. When I have the funds, I'll be upgrading the most of the components anyway (mobo, CPU, RAM, PSU, vid card). For now, I'm fortunate to have invested $50 in a phased out office PC, which I figure is pretty good for a 3.2GHz P4. At least I'm far more confident that this one won't catch fire.

Too bad I won't have an HTPC for a while, though.

Hi,

Most of the PC Power Supplies sense "Bulk" current for the main forward converter. The individual outputs especially for lower voltages (except for a common regulation node) are not current sensed.

It's likely that the main bulk converter didn't see enough of a change in current sense that it didn't recognize the problem.

Check for the mounting screws and washers shorting traces or planes to the Chassis around the mounting holes. Measure the current if you can of USB devices on the +5V. make sure there is a tie from 3.3V Ground to 5V ground in the system. Are there any shorted (and burned Tantalum capacitors or other Aluminum Electrolytic capacitors (tall cans) that look bulged on the motherboard.

Luckily, the mating connectors and motherboard were compliant to UL or something similar or you might have seen worse damage. The UL make is usually visible on the bare circuit board and will usually be 94V-0 (Flammability Specification) with a unique symbol of the Board Fabricator (not the usually the Assembled Circuit Card Vendor. There may also be a EXXXXX number that matches their UL Registation, sometimes called a Yellow Card. The circuit card assembly with the parts installed is known at the 94V-2 level and all of the parts installed (including your connectors) should meet 94V-1 or 94V-2 minimum. This is where government and industry regulation actually have been valuable. (grin)

I had a UPS that caught fire and you can still have problems, so, you can still have problems, but, it limits the damage.

The pins and the connector are damaged, I would replace them, or replace the motherboard.

Good Luck,

Ross

As I remember, the only thing that remained working was a very crap FM radio tuner card, being the cheapest component in the entire system

Hugo