PSUs and surge protectors

[The Silent Hobo]

I just had a friend/client of mine call me with a problem.

Background story: He had passed me his HP desktop to put a new power supply in cause that one somehow died and so it had a 180 watt one to begin with. ok, I order a brand new one off ebay for about $35, put it in, he was happy. This was back in July.

I just got a phone call from him (not even 3 months later) saying he bought a surge protector today and plugged the desktop into it, and then heard a pop and the desktop shut off. He's gonna be bringing it by tomorrow, but I wanted to ask if any of you have had any problems with a surge protector blowing a power supply.

Joshua

 

[Rob_NNCC]

new one off ebay for about $35

That is your problem, not a power strip. I pay $50 for my powersupplys as cheap ones are more trouble than they are worth.

 

[The Silent Hobo]

Yes, however, it's not a standard power supply unit (even though I wish it was), it's one of those hp slimline power supplies, which seemed to work great with no problems. Just doesn't make sense that it'd blow after being plugged into a surge protector.

 

[lenogris]

At best some internals were messed up on the surge protector, but there really is no good way to prove it.

I know on my ship our electrical system can ground out, and cause a lot of damage. Usually anything close to the ground gets screwed up, and the device that got the ground catches fire. Perhaps what he thought was a surge protector was actually a power strip, and he had another messed up device plugged in?

 

[The Silent Hobo]

never thought to ask him that, thanks Lenogris. He's supposed to be swinging by with it, and i read yesterday, that if you flip the 110/240 switch back and forth a couple times, it's supposed to discharge the electricity that's in there, not sure if it's true or not, but what's the harm in trying.

 

[lenogris]

i would also double check to make sure he did not have it on 240.

You from OKC or a suburb? im actually from macomb, out by noble.

 

[The Silent Hobo]

I'm actually right off of the kilpatrick turnpike and NW Expressway, outskirts towards Piedmont. Glad to see a fellow OKC'in on here

anyways, I don't believe he had it on 240 unless someone tried to play a practical joke on him, but i'll double check that one also.

 

[B Trevathan]

and i read yesterday, that if you flip the 110/240 switch back and forth a couple times, it's supposed to discharge the electricity that's in there, not sure if it's true or not

I don't know where you read that but, no it won't. Unplug the computer from the wall and unplug everything from the computer like monitor, printers etc. and then hold down the power button on the front of the computer for around 30 seconds. This drains the flea power out of the computer, mainly out of the large capacitors in the PSU.

and then heard a pop and the desktop shut off

The pop he heard could've been from a capacitor blowing in the PSU or on the motherboard. It could have also been other things like the surge protector detecting a surge and sending it to ground.

make sure he did not have it on 240.

I don't know why in the US he would have it on 240 but if he did it should just cause it not to start, but not blow the PSU.

 

[YeOldeStonecat]

Yes, however, it's not a standard power supply unit (even though I wish it was), it's one of those hp slimline power supplies, which seemed to work great with no problems. Just doesn't make sense that it'd blow after being plugged into a surge protector.

We get our replacement power supplies for proprietary desktop models from this place
http://serversupply.com/

In New York..so wouldn't take long to get to you.

 

[westom]

... that if you flip the 110/240 switch back and forth a couple times, it's supposed to discharge the electricity

Nonsense. No electricity is stored after about a second.

What does a surge proetctor do? Nothing until AC mains voltage exceeds a number. Read that let-through voltage number on its box. Maybe 330 volts. So, if voltage remains below 330 volts, then what happens? Nothing. Anything on AC mains connects directly to the computer.

Furthermore, if an effective protector does anything, then it does so silently. So that nobody even knew a surge existed. Unfortunately, a protector that actually does something useful is often not recommended. Because it does not fail, results in no damage, and does not make noise.

A most common reason for failure is manufacturing defects. One classic example is called infant mortality. Does that explain his failure? Nobody can say until (at minimum) each specific and failed part is first identified. Without such facts, then every conclusion is only wild speculation.

 

[YeOldeStonecat]

Nonsense. No electricity is stored after about a second.

Capacitors will and do store juice even after being unplugged....sometimes for quite a while. I have seen someone get kicked 10 feet across the room when he disassembled a CRT monitor within discharging it properly. Those used to hold a charge for days...even weeks after being unplugged.

But even little power supplies for computers have capacitors that can still pack a wallop.

This should have been part of your CompTIA A+ hardware training.

 

[westom]

Capacitors will and do store juice even after being unplugged....sometimes for quite a while.

All power supplies have a bleeder resistor. If that resistor fails, well, nobody cares. Because that energy is not a threat to any hardware or human. Did they forget to mention the always existing bleeder resistor and what is at risk? Therefore capacitors discharge within seconds.

Yes, a tech who opens a power supply should know about how capacitors work. Why every capacitor already has a bleeder resistor. And why a screwdriver discharges that capacitor - to identify and replace a failed resistor.

Why did you forget to mention the bleeder resistor? Why discuss opening a supply; that most techs and the OP have no reason to do?

Use a screw driver across the capacitor. Never switch the 120/240 volt switch.

Meanwhile, that additional information is irrelevant to the OP, his possible defect, reason for that defect, and a solution.

 

[Rob_NNCC]

All power supplies have a bleeder resistor. Why every capacitor already has a bleeder resistor.

Sorry, but this is just not true. The better the capacitor the less leakage it has.

What are you basing this on? Have you gone to college for ECE? CompTA says to NEVER open a PSU due to the stored juce in a cap. I almost never bother to unless I am messing around in my garage but when I do I always screwdriver short them and some hold current for more than an hour, esp. the AT and new ATX Gold cert. Active PFC type units.

If you would like, I can charge up some of my new unused 330V half a farad caps and see how long 240v takes to drop to 50V on no load. I bet it would be the better part of a day atleast.

I am just being to heavy on this as this misinformation could seriously harm someone.

 

[westom]

CompTA says to NEVER open a PSU due to the stored juce in a cap.

Of course. Those techs have no basic electrical knowledge. Would not know what to look for. Have no reason to open a supply. And it is irrelevant to anything the OP has asked.

Meanwhile we who even designed supplies generations ago know about bleeder resistors required across every capacitor. Typically a 100K resistor. Why would I even know the number and you do not? We also know if the bleeder resistor has failed, energy on the capacitor does not appear on any external parts. And that stored energy does not cause hardware damage (see an exception described below).

No bleeder resistor exists says you have near zero design knowledge. That bleeder resistor was required even in 1950 TVs. A little hint about to how much I do know, how extensive my experience, and how little you actually know. Your caustic comments are not only totally wrong but also insulting. Now, end your silliness. Address the OP's question.

OP was switching a 120/240 switch to discharge energy. That energy must bleed off in seconds. Switching that switch accomplishes nothing useful. If energy was stored in capacitors, then toggleing that 120/240 switch could even create hardware damage. Just another reason why every capacitor already has a bleeder resistor. That bleeder resistor means toggling a 120/240 switch does not cause damage. And toggling the switch does nothing useful.

Energy (that is not stored because every capacitor has a bleeder resistor) also would not cause his popping on powerup..

Considering too little posted information, best we can say is that the OP has suffered a typical manufacturing defect. Nobody can say anything more if a failed (popping) part is not identified.

No actions performed by the OP's friend should creating popping. But a manufacturing defect does explain it.

 

[YeOldeStonecat]

All power supplies have a bleeder resistor. If that resistor fails, well, nobody cares. Because that energy is not a threat to any hardware or human. Did they forget to mention the always existing bleeder resistor and what is at risk? Therefore capacitors discharge within seconds.

Yes, a tech who opens a power supply should know about how capacitors work. Why every capacitor already has a bleeder resistor. And why a screwdriver discharges that capacitor - to identify and replace a failed resistor.

Why did you forget to mention the bleeder resistor? Why discuss opening a supply; that most techs and the OP have no reason to do?

Use a screw driver across the capacitor. Never switch the 120/240 volt switch.

Meanwhile, that additional information is irrelevant to the OP, his possible defect, reason for that defect, and a solution.

"Why" you ask?
Because A) you mention no charge is held after a second or two, I disagree. Again...I've seen someone get sent flying across the tech room. He wasn't faking it just to try to fool you, his hand and arm didn't imagine the discomfort. And my eyes didn't image the scenario.
And B)..We...well, "some" of us...learned about capacitors and potential risk waaaay back in A+ class.

IMO, telling a general PC tech on a forum that "there is no electricity stored in there after a second two" is careless.

And...well.."We care" (well, lemme correct that...SOME OF US care) for most of our fellow techs here.

You're soap box speech about being an electrical expert...yippee yah yay for you, but I wouldn't assume that all other techs on a forum are properly trained on discharging capacitors. Hence I would hate to see someone harmed because they were told "nah...go ahead, dive right in..there's no juice left in there at all"..which is in effect what you are trying to thump over everyones head. Not smart!

 

[westom]

IMO, telling a general PC tech on a forum that "there is no electricity stored in there after a second two" is careless.

Can you please use perspective? Please stick to context. OP says energy stored in a power supply caused a power supply to fail when repowered. Nonsense. But if you know better, then explain how that energy caused damage without cheapshots.

He was 'discharging' energy (apparently) because energy might appear on external connections. Nonsense.

If energy was stored internally, then switching the 120/240 switch could cause damage. Just another reason why all capacitors are discharged by the bleeder resistor (that others 'know' does not exist).

Any tech that does not know how to identify a failed bleeder resistor (another manufacturing defect) deserves to be shocked. Routine is to discharge a capacitor with a screw driver ... to find that manufacturing defect. But that is completely irrelevant to this thread. And completely irrelevant to the OP's question.

OP's failure is most likely a manufacturing defect. Not due to anything his friend apparently did. If you know otherwise, then identify a reason for his popping with hard facts and numbers. Not with cheapshot insults.

Simple. If energy was being stored in his supply, then switching a 120/240 switch could cause hardware damage. Just one of many reasons why energy is not stored inside a PSU.

 

[angry_geek]

Actually, Mr electrical engineer who knows more than the rest of us, bleeder resistors fail all the time resulting in high voltage loads being stored in the caps. They're not "required" but merely recommended. Which means don't open the damn psu. Old TVs from the '50s and many crt monitors store voltages up to 30k. Imagine what would happen to the unsuspecting when they hit that one. You're right in that the popping could have been from a manufacturing defect. Or it could have been a surge when he plugged it in. Point is, something popped on a $30 part when he put power to it. Do you honestly believe it's worth the op's life to try to investigate? Better to test and replace the part. Switching from 120 to 240 will do nothing, but hitting the power button will drain most of the juice. Just don't open that box unless you really know your way around high voltage circuitry, which isn't really necessary for most techs in the field.

 

[westom]

Actually, Mr electrical engineer who knows more than the rest of us, bleeder resistors fail all the time resulting in high voltage loads being stored in the caps. They're not "required" but merely recommended.

So you begin with an cheapshot to prove superiority. No facts. No numbers. Just an assumption that the bleeder resistor is not required when it was always required. Energy stored in capacitors might even cause damage when the 120/240 switch is toggled. That is acceptable? Explain why energy stored in a PSU is acceptable? That potential damage is one of many reasons why the bleeder resistor always exists.

Please read what has been posted multiple times.

Any tech that does not know how to identify a failed bleeder resistor (another manufacturing defect) deserves to be shocked. Routine is to discharge a capacitor with a screw driver ... to find that manufacturing defect. But that is completely irrelevant to this thread. And completely irrelevant to the OP's question.

So where did you post something helpful to the OP? Pressing the power button would not drain capacitors. Obvious from concepts (how a PSU works) too complex to explain here. A myth that also is not OP helpful.

Best anyone can say (from insufficient information): the OP has suffered from a manufacturing defect.

Why dwell on a problem that is both irrelevant and must not exist? That can only exist due to a manufacturing defect? That only confuses the OP with irrelevant statements?

Popping did not occur because energy was stored in the PSU. Or due to what his friend apparently did. Most likely reason for that failure is a manufacturing defect. If you know otherwise, then explain it with facts and numbers. Context is defined in the OP's original post.

 

[YeOldeStonecat]

Can you please use perspective? Please stick to context.

I already clearly s-p-e-l-l-e-d out my point. 'nuff said.

 

[angry_geek]

I began with a cheapshot because you already clearly stated that you believe you know far more than the rest of us. Several of us here are licensed electricians and some hold ee degrees. Just because you think you're superior doesn't mean it's so. It just makes you a narcissist. I addressed the OP. Or do you find reading comprehension to be too menial for you? Replace the psu, and move on.