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power surge?

  • Power Surge
  • Components
Last response: in Components
April 20, 2003 4:33:58 PM

ok.. I'm currently having a 300watts approved AMD PSU in my PC, and has been running stably for over a year.

the PSU is connected to a 4-way multiplug which has individual switches for all 4 sockets, which has my PC, cable modem, a digital timer and handphone charger conencted to it. Usually, I off the electrical supply to my PC and modem whenever I leave my house. I off them by turning off the switch on the wall socket which the multiplug is connected to, thereby cutting off power supply to all my components with just 1 switch.

however, yesterday, as usual, I on the electricity to my PC and modem by turning off on the wall socket switch. My modem and digital timer immediately comes on at the same time, but alas, there was a loud bang, and some green light, and some burning smell, and there goes my PSU. Had to buy a new 300W PSU, which again ran smoothly on my PC. My question is, what exactly was wrong? I've always been turning on everything like this all my life. And the weather was good, no lightning. Sunny.

The multi-plug was just a normal one, no surge protection or anything. I hope someone can tell me what exactly was wrong? Would buying a surge protected multi-plug help? I can't really imagine if someone was just standing in front of the PC when that dreadful zapping happened.

And also, it's not as if the PC immediately boots up once I on the wall socket switch. I'd still need to boot the PC up by hitting the power button on the case. thanx

The No. 1 cause of divorce is marriage - 100% of all divorces starts with marriage

More about : power surge

April 20, 2003 5:19:52 PM

Ok, here's the scoop...
When an ATX computer is "off" it's not really OFF it's just in a very deep standby mode.

ATX PSUs are not designed to be turned on and off all the time. The switch on the back of your case is a "service switch" intended to be shut off only when the machine is being serviced. The primary side of the power supply is intended to always be live waiting for the "power" switch on the front of the case to be pressed. Thus, it won't necessarily be designed to repeatedly handle charging those huge capacitors, which can draw an alarming amount of current for a split second. (At the instant of power on, a capacitor is effectively a dead short and will draw considerable current until it is fully charged.)

By switching the AC outlet as you do, you are effectively operating the power supply outside it's design parameters and it is likely that the repeated current surges have finally taken their toll.

The same is true, by the way, of the power supplies in televisions, monitors, printers, microwaves, stereos etc. These devices are designed to always be powered up, and "Off" is merely an inactive state.

When you get your new PSU... leave the wall outlet active all the time, it will thank you for it.

--->It ain't better if it don't work<---
April 21, 2003 12:42:30 AM

I'm darned glad that you wrote this. Thank you.

I've got an elderly customer who plugs everything into an old surge protector, and he uses that to turn off the computer. "Everything" consists of the CPU, monitor, scanner, printer, speakers, a CD carousel, a powered USB hub, a lamp, and God only knows what else. I think the only thing that runs on the system once it's been in his hands for a few weeks is CHKDSK.

I've been telling him for the past year that leaving all the devices on, and then using the surge protector to cut the power was a very bad idea. No matter how I worded it, he assumed I was talking over-my-head, simply because he was a microwave engineer about 25 years ago. (And they talk about the arrogance of youth!)

I've replaced his scanner once, and the power supply twice. He's a got a pretty power-hungry configuration, and won't let me install anything except cheap, generic 300W Deer PSU's, (he swears that anything else is a waste of money) so it doesn't take long before the surges knock out the PSU and he is calling me, complaining of smoke coming out of the back of the case. I don't know which of us is more irate after the phone call, since he demands that I drive to his house to install the device, and I have to make an effort to locate and install the same PSU, regardless of the quality, or if I have it in stock.

Some customers are definitely more work than others.

It will be interesting to hear his reaction when I send him a link to this thread. Finally ... some vindication! LOL!


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April 21, 2003 12:58:35 AM

I had one customer like that... cost me a bundle in warranty service. One day I went out there empty handed and said "I'm sorry I don't have the right supply in stock for your machine, I'm gonna take this one back and fix it. I should have you up and going first thing in the morning.", took the power supply with me, put the guts out of a 350watt supply in his old 200w casing, cleaned it all up and went back the next day and installed it. It's been a couple of years now and I haven't heard from him since.

Really... the primary sides of these switching supplies are not intended to be repeatedly turned on and off. They're good for a hundred or so powerups and then they're gonna let go.

--->It ain't better if it don't work<---
April 21, 2003 5:13:26 PM

Uh oh... then I should be in deep sh¡t now.

After I shutdown my PC I always unplug it from the wall socket... otherwise my watercooling pump stays humming which is a rather irritating noice in total silence (not that it is loud)... and my dad wont like it if I keep it connected). The average is that this happens about once a day. Maybe I got decent PSUs or the Dutch electricity supply is very 'clean' but I never had a PSU go bang... even my old ATX PSU my bro now uses that has been switched on/off for more then thousand times still runs good.

Maybe I'm just lucky.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
April 21, 2003 5:38:55 PM

There's an easy way to fix the buzzing pump problem...

Either get a 12volt pump that runs off a drive connector


Get a 12vdc relay switch, use 12vdc from the disk drives to pull in the relay and use the relay contacts to switch the AC to the pump.


Add a small AC switch for the pump itself to the outside of the computer someplace.

--->It ain't better if it don't work<---
April 21, 2003 7:20:23 PM

Yeah I know that a switch will do the job... although I'm afraid I'm going to forget to turn on the pump some time.

But then I still got the problem that my dad doesn't want me to keep my PC plugged in... and he might be just as difficult to convince as those customers.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
April 21, 2003 9:47:32 PM

oh man, im familiar with that one, is it cause it drains power?

my computer is so fast, it completes an endless loop in less than 4 seconds!
April 21, 2003 10:07:39 PM

If you're afraid you will forget the pump go with the relay option and have the pump start up with your computer...

(If this BBS would allow images, I'd give you the schematic, it's real simple)

--->It ain't better if it don't work<---
April 22, 2003 1:02:19 PM

If you're talking about why my dad doesn't want it: yes, and in case of lightning.


My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
April 22, 2003 1:03:50 PM

Oh a relay wont be a problem for me... I want to start studying electrotechnics next year so I will be able to set up a relay.

Now I only need a 12V or 5V relay that can be used with 230V power sources.

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
April 22, 2003 3:27:06 PM

Yep... There's lots of them out there. Check around your local electronics supply houses, bet you find a good one for only a couple of bucks.

12volt coil, single or double pole contacts should work fine. Douple pole would let you cut both sides of the AC effectively doubling the switch's voltage rating.

--->It ain't better if it don't work<---
April 22, 2003 3:28:20 PM

And when was the last time lightning hit your house? :smile:

--->It ain't better if it don't work<---
April 23, 2003 11:12:04 AM

It never happened. :eek: 

My dual-PSU PC is so powerfull that the neighbourhood dims when I turn it on :eek: 
April 24, 2003 1:43:10 AM

I've actually had lightning hit the pole in my backyard 3 times in the past 4-5 years or so. It was such a bad power surge my APC UPS didn't even save my computer from rebooting, but it didn't harm anything. I have a UPS on almost all the main electronics, all 3 computers, and my parents big tv set just to make sure it doens't become a victim.
April 24, 2003 8:32:36 AM

Toejam31, wouldn't it be cheaper for you to install a high quality power supply in that customer's system, even if it's out of your own pocket, because of all the service calls it would eliminate?

I don't see why an ATX power supply shouldn't be switched on or off by a power strip or the rear rocker switch because old AT supplies were always switched that way, via a large red paddle switch on the side, and the primary side circuits aren't that different, except for the standby +5V supply. The only reason I don't use the rear rocker switch much is because I can't buy another one easily if it breaks, at least not if it's double poled.
April 24, 2003 11:28:02 AM

Yes, of course it would. But it's not my computer, and I couldn't force the customer to install a better unit; I could only <i>suggest</i>. I would have gladly absorbed the extra cost, but that wasn't my decision to make. I built the computer from a parts list supplied by the customer, and he was very specific about what he wanted. The only choice I had in the matter was whether to build the system or not in the first place. If it hadn't been me, it would have been someone else.

It might have been a different story if the system had refused to boot when first assembled, but I didn't get that lucky.

Imagine the situation in reverse. A component dies in your system, and your local tech insists on installing a different replacement part that you know for a fact is <i>inferior</i>, despite your vehement protests. How long would your business relationship continue with this individual?

The customer is always right, even if he really isn't.

People can be quirky. I had a long-time customer who insisted that the only correct way to copy a floppy disk was with DOS 6.22, and as such, insisted I create a partition and install the OS on any new system he bought. This was the <i>only</i> reason he wanted the operating system.

It was harmless, and so, that's exactly what I did. But nothing I said could convince him that it was a waste of disk space. This had always worked for him in the past ... it was what he was accustomed to doing, and it was his personal preference.

I didn't waste a great deal of time arguing with him; I installed the OS, set up a multi-boot with whatever else he wanted (which included System Commander, because he loved to show off to his friends how many operating systems he could load ... which was usually five, including OS/2 Warp), and I hoped he was happy with the end result.

Certainly it would have been less time consuming to install one OS. But it wasn't my computer ... it was his. And he <i>did</i> pay me for the labor, so I didn't complain. Complaining to, or about a customer is not in my job description, so I try to keep it to a bare minimum.

As for the previous customer, he also paid me for the labor, although not for the component, which was covered by my warranty. If I have to make a house call that is more than twenty miles from my location, then I charge extra. He could have brought me the system, and then it would have cost nothing for the repair, but again, that was up to him.

Computers are simple. It's people who are complicated! :smile:


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April 24, 2003 2:49:49 PM

Take a look at the construction of these power supplies... put an AT supply beside an ATX one. With the exception of the high end ATX supplies, you will see a very real difference in the way the primary rectifiers are designed... the cheaper ATX supplies will be using lower rated diodes and probably won't have safety resistors in them at all.

High end ATX supplies, which are far better designs, will take the AC being turned on and off all the time, but the cheaper "generic" supplies provided with most cases simply aren't built for that... some don't even have AC switches on them.

Just because they do the same thing doesn't mean they are identical in design.

--->It ain't better if it don't work<---
April 25, 2003 2:17:55 AM

In the ones I've seen, the rectifiers are about the same, whether AT, ATX, or even XT, meaning they still varied a lot. The cheapest one used diodes rated for only a bit more than the peak current and a jumper for the thermistor, the mid-priced one had a thermistor and bigger diodes or an integrated bridge, and the highest priced one also had a heatsink bolted to the bridge.