Power suppy took out my system (sigh)

riredale wrote on 1/16/2006, 11:34 AM
When something goes "poof" it's sometimes hard to tell just what went first.

My old reliable AMD 2100XP system began doing strange things last December. It would occasionally shut down completely, and once in a while it would reboot. Then, on December 30th, an acrid smell filled the air. System wouldn't boot at all. I first tried swapping the power supply, but the new one would shut down, implying to me that something on the board or in the peripherals was dragging it down.

I looked inside the power supply, and several of the caps had leakage, and there was evidence of scorching on the circuit board. I then checked out the motherboard, and 3 of the caps had convex tops. This is a big no-no, as it implies that the capacitors have either already failed or are about to. There is a story going around the Internet that a Taiwanese capacitor manufacturer stole the formula for capacitor electrolyte, but got the composition wrong, and ever since the industry has been flooded with capacitors that work fine--for a while.

Anyway, I bought a replacement motherboard on eBay ($31!) and swapped my BIOS chip. Still no go, though I get the BIOS screen. Digging deeper, I discover that my Pioneer 107 burner appears dead--door won't open when power is applied via the Molex connector in back. Wait, there's more: my Seagate 80GB drive (my C drive) doesn't spin. This is the drive that always ran hot enough to fry eggs on, so I was always amazed it ran at all. I got about 4 years from it.

So now I get to slowly rebuild my system from the image and Retrospect backups over the next few days. Funny thing is that I was planning to soon swap over to a new AMD X2-based system. Just won the Asus A8V deluxe motherboard on eBay late last night. But I want to do a swap from a fully functioning system, in case I need to g back for some reason.

So the question is, what failed first? My guess is that the motherboard went out of spec, frying the power supply, which put a spike on the power feeds, and the Pioneer and Seagate boxes couldn't handle it.

Comments

Former user wrote on 1/16/2006, 11:53 AM
I have read many reports about power supplies taking out the motherboard and associated components. I would lean more toward the PSU going first.

Dave T2
johnmeyer wrote on 1/16/2006, 3:24 PM
I have done LOTS of component level repair on all sorts of power supplies, both linear and switching. Bad caps are the problem almost all the time.

The power supply fried your computer, not the other way around. Power supplies are designed to survive even a short circuit across the output, so there is not much that your motherboard or DVD burner could do to harm the supply. However, most internal components have very little protection against much of anything.

The switching power supply used in computers usually just dies. I suppose it would be possible for the regulator circuit to get fried which would cause the output voltage to rise to whatever maximum the supply could produce. Usually this isn't something that would fry your components, but I'm not saying it couldn't happen.

The usual cause for something like you describe is a lighting event, but since this happened in December, I assume you didn't experience anything like that during that time period.

craftech wrote on 1/16/2006, 7:24 PM
Unfortunately much of the problem is a result of bogus power supply power ratings, but that doesn't help you right now.
I would test the other devices in a different computer if you have access to one before assuming they are actually dead. I would be surprised if they actually are. The 12v rails aren't usually the biggest problem.

I would also replace the bulged caps on the original mainboard around the CPU. It isn't that hard to do.

What is the model of the new PS you bought?

John


riredale wrote on 1/16/2006, 11:59 PM
WOO HOO!

Back online with the desktop system. I swapped in the eBay motherboard, used a new power supply, and after fits and starts I got things running again. I had a new spare WD120GB drive that I was able to load with an old C image, then updated the image with Retrospect. I was lucky that I had a Retrospect backup right up to the day the smoke began coming out of the sick PC a few weeks ago.

So I'm typing this on the repaired system. I lost a power supply, my Pioneer 107 DVD burner, and my Seagate 80GB drive. I doubt it was lightning, since up here in Portland Oregon I can count the days per year with lightning on one hand. But branches from the tall douglas fir trees fall on power lines all the time, so who knows.
riredale wrote on 1/17/2006, 6:51 AM
Well, the bad power supply took out out an additional hard drive. I hadn't realized it until I swapped it back in--it's a drive mounted in one of those plastic carriers that mates with a receptacle in the drive bay.

It's one of those WD120GB drives, and I have several other identical units around. Anybody ever try to swap the controller card on the bottom of a drive? The bad drive won't spin up or show any signs of life.
JJKizak wrote on 1/17/2006, 9:12 AM
I tried to apply some of those UPS systems on our plastic forming machines with no success because of how they juice the ratings. I needed about 4 of them in parallel to get enough power to run some very minor solenoid valves. They also put out square waves and not sine waves when the battery takes over. The square waves contain every frequency known to man. They are also very slow to switch---.5 seconds which in industry terms is iccky-poopoo. The resultant transient could also fry your computer.

JJK
craftech wrote on 1/17/2006, 4:20 PM
It's one of those WD120GB drives, and I have several other identical units around. Anybody ever try to swap the controller card on the bottom of a drive? The bad drive won't spin up or show any signs of life.
=====
Check the date on it. Up until a year or so ago WD had a three year warranty on those. Two of mine fall under that same warranty and the third (bought last year) falls under the new one year warranty (with option to buy an extension....which I did not. If it is under warranty, WD will replace it with a refurbished one without extra charge.
Replacing the PCB won't work if the motor has failed. You can try rebooting 4-5 times to see if it will kick start. Before tossing it (if it is NOT under the warranty you can try putting it in a plastic bag and then in the freezer to shrink the parts. Then remove it and hook it up to the cables to see if the motor will turn. Let it run if it does and see what happens.

John