Did My Psu Go Out?

Discussion in 'Hardware' started by cornflakes, Nov 5, 2023.

  1. cornflakes

    cornflakes Corporal

    I shutdown my PC but I didn't switch off all the power bars/outlets it's connected to.
    I also have about 3 or 4 external HDDs connected to the PC via usb.

    I left home for about 2 days. The day I came back home it was raining so not sure if weather
    may have done something to the power supply.

    When I came home, the first thing I noticed was my Focusrite Scarlett Audio interface
    was flashing lights on all it's dials on and off in 2 or 3 different colors. The PC was still off
    but I also noticed a couple of the hdds were on still and sounded like it was doing something in
    repeat but the PC was off.

    Since I didn't switch the power supply off nor did I press the button at the back of the PC psu
    that let's you switch power off (even though PC is off), I guess the PSU is still drawing power and
    supplying it to the ext hdds and the focusrite audio interface?

    When I tried to turn the PC on, it didn't respond. No lights, no fans, it just didn't power on.
    I checked for everything like loose cables/connection and power switch on and off and other power bars
    or directly into the wall outlet and it wouldn't power on at all. If I unplug and plug the usb connectors
    for my focusrite, it will still flash all kinds of lights on and off. So I unplugged the usb from the pc and
    plugged it into my laptop and it doesn't flash crazy lights anymore.

    My best guess is that it's the PSU and that it's gone....but somehow was still drawing enough power
    to make the focusrite audio interface dials flash all colors and power on my ext hdds even though
    the PC wasn't powered on. So maybe the PSU is drawing power still but not enough power anymore
    to turn on?

    Any suggestions?

    Forgot to mention, my PSU is a Corsair CX600.
    I've had it for about 5.5 years now.
    I've had no symptoms of power supply failure/failing over the past several days prior....no symptoms such as failing to turn on sometimes or PC shutting off intermittently or BSOD or freezing up. There were no symptoms of a failing PSU.
     
  2. Digerati

    Digerati Major Geek Extraordinaire

    For what its worth, I never shutdown or disconnect from the wall outlet unless I will be away from home for several days. I just let my computers go to sleep.

    The ATX Form Factor Standard requires all ATX compliant PSUs provide +5Vsb standby power to multiple points on the motherboard whenever the PSU is plugged into the wall and the master power switch on the back of the supply ("if" it has one) is set to "On" (or "|"). This standby power is needed for several functions to work, such as "Wake on Mouse", "Wake on Keyboard" and even the front panel power button (which is really a "remote" switch). This also means there is still +5V present at some or all of the USB ports to keep connected devices alive (or at least in standby mode). On some motherboards, there is even one or two USB ports kept alive with "high power" +5V so you can charge your cell phone, for example, when the computer is not awake.
    The ATX Form Factor Standard also requires all PSUs output 3 primary voltages; +12VDC, +5VDC and +3.3VDC along with that +5Vsb voltage. If any one of those primary voltages are missing (or way out of the allowed ±5% tolerance) the computer will fail to start.

    It does indeed sound like your PSU has failed and the only way for "normal" users to verify that "conclusively" is to take the supply to a qualified technician for thorough testing, or to swap in a known good supply. I note even the best supplies from the best makers can have a unit fail prematurely. That said, the CX line from Corsair is their bottom "basic" tier line of supplies, and it has already served you well for 5 1/2 years. And since EVERYTHING inside the computer depends on good, clean, stable power, it is essential we supply it. Therefore, I recommend swapping in a known good supply.

    I prefer a quality 80 Plus "Gold" supply from Seasonic or EVGA. If you want to go with Corsair again, I would urge you to go with their upper tier lines, at least their TX or RM series. A few years ago they changed suppliers for their entry level models.

    I don't recommend going with 80 Plus "Platinum" or "Titanium" supplies unless you just happen to stumble upon a great, sale price. They are more efficient than "Gold" certified but only by a couple percentage points. It would typically take years of use to make up for the normally higher costs. Gold supplies are rated at least 87% efficient across all load levels - which is most excellent. If the budget is really tight, go for at least a "Bronze" from a reputable maker.

    One last thing. Since this PSU is 5 1/2 years old, then I am going to jump to the conclusion that the rest of the computer (motherboard, CPU, RAM, drives, graphics solution) is too. Any one of which could last for years to come, or die tomorrow.

    I recommend you think ahead at what you will be looking for in your next computer, and buy your replacement PSU (if you don't have a spare handy laying around) accordingly. Then you can carry that PSU to the new build. If you already know exactly what you want, then size for that. But if unsure, you are just going to have to guess. Clearly 600W has been fine with your current computer.

    Typically, unless you are a hardcore gamer, ~600 to 650W is a good size for most users. But if you will be looking at serious horsepower in your next CPU and especially graphics solution, you may want to look at 750 - 850W.

    Buying too big hurts nothing, but perhaps your budget. Buying bigger than you need lets the PSU "loaf" around. Most PSUs are most efficient at 50% load so that's a good focus point. And when most efficient, there is less loss in the form of heat. A good thing. And less heat means the PSU's fan should be able to spin at a lower speed, or even totally off most of the time. And that means no fan noise - a most excellent thing (I really hate fan noise). You definitely do not want an underpowered supply so if any doubt, go bigger.
     
    cornflakes likes this.
  3. foogoo

    foogoo Major "foogoo" Geek

    Is the power supply's fan going? Was it on all the time previously? Some are thermal & only turn on when hot.

    1) Unplug the power supply from the back and push the power button for a second - then plug the power back in and hit the button.

    2) Unplugg *everything* KB, mouse, any USB devices..- leave power cord to PC and cable to the monitor and redo step one to drain it, then power it back on.

    3) Opening the case and remove *everything* but the jumpers for the case, power cables to the mobo... so all molex to drive cable removed from the drives..so you have CPU, RAM, Graphics card (if not on board) and try to power up.
     
    cornflakes likes this.
  4. cornflakes

    cornflakes Corporal

    Thank you. I will try a new ps tomorrow and see how if that was it
     
  5. cornflakes

    cornflakes Corporal

    Hmm I have tried most of it like removing all connections and trying it with no success. But I will try this draining thing. Never knew that. Thank you guys for the advice!
     
  6. Digerati

    Digerati Major Geek Extraordinaire

    If a PSU "needs" manual voltage bleeding (draining), the PSU is defective. Period.

    And even if defective (unless - maybe - severely and obviously physically damaged), if the supply is plugged into the wall (directly or through a strip), the supply and thus the computer "should" still be grounded through the supply's power cord - unless it is severely damaged too. Therefore, any residual voltages will quickly decay through the ground within a 1 or 2 seconds. Even if unplugged from the wall, PSUs are designed to quickly bleed off any residual voltages that might be stored in any capacitor to "safe levels". This happens within a second or two - again if NOT defective.

    And sorry, but once the supply is unplugged, the +5Vsb voltage that runs through case's front panel power button is long gone. Pressing the power button at that point does nothing but smash your finger.

    This suggest does have it's roots in fact. Many MANY years ago, before the ATX Form Factor Standard supplanted to long-obsolete AT Form Factor, pressing the power button might have helped because the front panel power button was directly tied back to the power supply via a large wiring harness. But as I noted above, with the ATX Form Factor (which came out in 1995!), the front panel power button is just a remote button.

    Now for sure, I am talking about PCs, not laptops.
     
    cornflakes likes this.
  7. cornflakes

    cornflakes Corporal

    Is it possible the actual power button or the connectors to the power button at the front of the case could be malfunctioning and nothing else is wrong? I was trying to figure out how to check for that but have no clue other than to make sure the wires are properly connected and they are. But what if the power button itself isn't working and therefore not telling the psu to even power on?
     
  8. cornflakes

    cornflakes Corporal

    I was able to power on an older pc using this psu. The psu fan was running. The only thing I swapped out was the power connector on the older pc and plugged it with the corsair cx600 one and it powers on. Does this mean the psu actually still works but something else is then wrong with my current pc?

    Or could it mean the psu is still dying and only able to output lower power enough to turn on an older pc but not enough power to turn on my current pc? Or could there be something else wrong with my current pc?
     
  9. cornflakes

    cornflakes Corporal

    I also tried the paper clip test on cx600. The fan spins when I connect the 4th pins with a paperclip. But when I connected the case fans at the front via molex connector and tried the paperclip test, the psu fan spins but the case fans (3) at the front weren't spinning.
     
  10. cornflakes

    cornflakes Corporal

    Update: got my new PSU and plugged it in with just power cable and the pc still wouldn't turn on.
    I plugged in everything else (cpu, pci e, and the molex connector, and hdds sata) and still would not turn on.

    So it doesn't look like it's the PSU issue. I'm guessing it might be the motherboard got fried?
    I don't game, my pc was fine when I left it. I shutdown but didn't turn off power bar so all usb connectors
    were still on connected to my hdds, my focusrite audio interface which was flashing colors when I came back
    home (I read that it meant its not drawing enough power). I do have my power bars and PC connected to
    an APC UPS that I've been using for a few years now in the surge protector outlets. The battery backup ports
    dont work anymore because the apc ups battery is dead and needed to be replaced but I kept it to just use the
    surge protector ports.

    Any ideas what to do next? I'm also afraid the fix might be easy and if I try to sell this pc for cheap like a hundred
    bucks, some tech savy guy might fix it up for $100 and have himself a $1500 pc lol.
     
  11. cornflakes

    cornflakes Corporal

    I had a technician service take a look at it and tested the corsair cx600 and said it's fine working. He said
    the mobo is gone. So I guess I have to replace the mobo :(

    Cost me $30 just for him to check and tell me that. I guess that is normal
     
  12. cornflakes

    cornflakes Corporal

    UPDATE: since my mobo is over 5 years old, not easy to find new ones, but only refurbs. I've ordered a compatible mobo
    and will arrive in 3 days so I'll attempt my first ever mobo installation. Any tips I should know about when doing this?
    I've watched a few yt videos to prepare myself lol. Ground myself, don't tighten too hard, remember where all the connectors
    go (take photo or video of the process to recall if I forget). One question I have is, do I need to purchase thermal paste when
    doing this installation? So I have to remove the CPU from the dead mobo and then reseat it into the new mobo? Then when I reinstalled the cooler (mine is a Coolermaster Hyper T4) do I need to put some thermal paste on the cpu?
     
  13. Digerati

    Digerati Major Geek Extraordinaire

    You ALWAYS need to thoroughly clean the mating surfaces (I use 91-93% isopropyl alcohol) of the heat sink and CPU after removing the heatsink. And you ALWAYS need to apply a fresh, new, thin as possible but thorough layer of TIM (thermal interface material) when mounting or remount a processor.

    Yes, ground yourself. Or more accurately, make sure you and the computer are at the same potential by frequently touching bare metal of the case interior.
     
    cornflakes likes this.
  14. cornflakes

    cornflakes Corporal

    thank you I will watch more videos to prepare for this.
     
  15. Digerati

    Digerati Major Geek Extraordinaire

    While waiting for delivery, you might also go out and visit the motherboard's webpage and download the manual. Same with your power supply, graphics card, even case. These usually have the installation/mounting instructions (in 42 different languages). You can then become familiar with the terms, and connector locations, mounting points, etc.

    Of course, I am assuming you have another computer to do this with but since you are still posting here, I assume you do.

    Another word of caution. Note that cases are designed to support 1000s of different motherboards of different sizes. So, it is common for cases to have more motherboard mounting points than some boards have mounting holes.

    A common mistake by the less experienced and distracted pros alike is to insert one or more extra standoff in the case under the motherboard. Any extra standoff creates the potential for an electrical “short” in one or more circuits. The results range from "nothing" (everything works perfectly) to odd problems, to "nothing" (as in nothing works at all :(). To add to the confusion, these issues may be intermittent, depending on heat, expansion/contraction of materials, as well as continuity/resistance through the contact point. Therefore, you need to ensure your case only has an inserted standoff where there is a corresponding motherboard mounting hole.

    Note the latest version of the ATX Form Factor standard hopes to eliminate these issues by dictating where standoffs will go, not just where they may go. But not all existing boards or cases comply with those latest standards. So, even with a new board, you still should verify you only inserted a standoff where there is a corresponding motherboard mounting hole.
     
    cornflakes likes this.
  16. cornflakes

    cornflakes Corporal

    Wow thanks for the heads up! I'll keep my eye on that too. It's my first time trying this so hopefully it will be a good experience.
    The current mobo that died was an ASRock B270M Pro4 mini ATX. The one I am replacing it with is Gigabyte GA-B250M-DS3H
    also a mini ATX. My case is Akbo NCore Sapphire Tower. I have an intel i7-7700K cpu. I ordered thermal paste so and have rubbing alcohol already so I'll clean the heat sink and then apply like 2 rice grain size of paste at the center of the cpu. That's what seems to be the way to do it before putting the intercooler back on it. I'll have to look up standoff in the case as I'm not familiar with this term or what it looks like.
     
  17. Digerati

    Digerati Major Geek Extraordinaire

    Umm, I included a link to an image of one.
     
    cornflakes likes this.
  18. cornflakes

    cornflakes Corporal

    BTW, I don't know how or why it died. I don't think it was due to just being old since it was only 5.5 yrs old. I've heard mobo's can last up to 20 years even. Of course anything can just malfunction and die I suppose but it seems more likely something caused this to get fried or die. I don't see any burned parts. I did detect the faintest of burning smell just for like a second when I was plugging it in and trying to power it on a few times but the smell was so faint and literally gone after 1 second I couldn't smell it anymore....so not sure if my mind was playing tricks on me or something really did get fried but can't see it.

    As I mentioned in my first post, I shutdown the PC as I always do and left for 2 days out of town. I forgot to turn off all multi taps/power bars and usually I turned off the computer switch at the back of psu too. Since I didn't I'm not sure if all my hdds and other usb devices that were left connected into the pc were drawing power or doing something funky and caused one of the usb ports
    to short or fry the mobo? The day I came back home, it had rained that day so there was storm on and off but not sure if that had a part....I'm plugged into an apc ups surge protector so I don't think the weather could have damaged my pc ....I've gone through many stormy days without any electrical problems to my pc but who knows. I came home and first thing I noticed was my focurite audio interface was just flashing and blinking lights like crazy. It was plugged in via usb. When I unplugged it and plugged it back in, the lights were flashing crazy again (even though the PC was off but the psu switch was still on and power bars still on).
     
  19. cornflakes

    cornflakes Corporal

    These standoffs....are they provided by the motherboards? So if my mobo comes with more standoffs than my case has holes for them, just use the same amount as holes in the case and don't install the extra standoffs right?
     
  20. Digerati

    Digerati Major Geek Extraordinaire

    There are several different sizes of standoffs. They are used to ensure the mounted motherboard sits up at just the right height so all the ports and slots on the back of the board align properly with the corresponding holes in the back of the case. So standoffs come with cases, not motherboards.

    I note not all have the same thread count either. So even if the height is the same, the threads might not match. Hopefully, the new board uses the same number (or less) standoffs than the old.
     
  21. cornflakes

    cornflakes Corporal

    Update:

    I replaced the motherboard with new compatible one (refurb and certified technician all working if that means anything lol).
    I'm pretty sure I followed all the steps correctly. I used the exact amount of standoffs and they fit perfectly, I reseated the cpu perfect and thermal paste with cooler back on. I plugged in all relevant cables.

    When I pressed the PC power button, I got power this time and system appeared to be running but none of my monitors showed any activity (no messages, no bios loading etc)....I tried one monitor first and then multiple others, I tried it on just the mobo and then the graphics card. The fans are turning except on the gpu...not sure if the fans always turn on the gpu or not when just starting up?

    Could it be the gpu went out too?
    How can I test if the gpu is working or not other than to see if the fans are turning?

    I'm ruling out the PSU since the technician who checked my PSU said it is fine and holding normal voltages.
     
  22. cornflakes

    cornflakes Corporal

    the cpu fan was unplugged so i plugged it back in and also I decided to connect my monitor to the gpu instead of the mobo and now it started up fine and booted straight into my windows so I didn't need to reinstall windows.

    However, after it booted up fine this one time, I added all my other drives back (2 more) and not sure if it matters which sata connector I plug it into but now it asks me to select the boot media and restart and I chose my drive that was the original boot drive with windows installed and everything but it's not loading it up. It still asks me each time to select a boot device now.
     
  23. Digerati

    Digerati Major Geek Extraordinaire

    It does not matter what SATA port you use, but you do need to set the boot priority in the BIOS to tell the system which drive the OS is on.
     
    cornflakes likes this.
  24. cornflakes

    cornflakes Corporal

    Ok that's reassuring. I have set the boot priority to the main drive that was the boot up drive originally. It still says to select a proper boot device and restart each time I boot up now. The very first time I booted up, it actually went straight to windows and my desktop where I saw everything as it always had been before swapping out the mobo. For some reason after that boot up, now it won't load windows anymore. Did something happen to my boot drive?
     
  25. cornflakes

    cornflakes Corporal

    Ok I got it all sorted out now! Oddly, in the boot option menu there was my ext hdds and my main ssd drive where the OS and it wasn't working when I selected it but I saw a blank spot/line with no text so I clicked on that as my boot device and it worked. Everything loaded perfectly. So back into the bios and i disabled boot priority and oddly it works perfectly now.
    o.o

    Anyways, I successfully swapped out my old mobo with a new one and everything works fine now. Hopefully it nothing goes bad a few days later.
    Is there a way can monitor the temps of all my components to make sure it's operating at healthy temperatures and not overheating? I just want to make sure I did a good job with the thermal paste
    and all the fans were reconnected properly and cooling the system and parts.
     
  26. Digerati

    Digerati Major Geek Extraordinaire

    Great! I am glad you got it sorted out and thanks for posting your solution.
    "All" your components? No. This because only some of the components have temperature sensors associated with them. But you can monitor the more sensitive/critical components.

    Probably the best program is HWiNFO64. It is very informative - perhaps overwhelmingly informative with all the information it can provide. Therefore, when using for the first time, I recommend you select “Sensors only” when prompted. Then scroll down to your motherboard’s section to see the temps.
    HWiNFO also includes an excellent notification/system “Tray Icon”, though it is bit challenging to setup, again because of the massive amount of information and options provided by the program. Under Sensors Status > Configure Sensors (the gear icon), select the Tray Icon tab, scroll down to and click on “Core Max” to highlight. Then click on “Show in Tray”. Then OK to set. If you want HWiNFO to run all the time you will need to select “Auto Start” from the "Main Settings" window.

    That said, I use HWiNFO as an "on-demand" system monitor. For "real-time" monitoring, I use and recommend Core Temp to monitor my CPU temps in real time. Under Options > Settings > Notification Area, I have mine set to display "Highest temperature" only.
     
    cornflakes likes this.
  27. cornflakes

    cornflakes Corporal

    Thank you all. I just checked with my bios and temperature for CPU seems to operating at normal levels. PC is working fine so far and all looks to be smooth and operating well!
     
  28. LJR

    LJR Private First Class

    With most (if not all) Mobo's, if you have a graphics card installed (and being used) you have to have the "on-board" video disabled, so that seems normal operation. (The setting should be in the BIOS somewhere to disable the on-board video.)
     
  29. Digerati

    Digerati Major Geek Extraordinaire

    Ummm, LJR, the OP reported nearly 3 weeks ago, his system is working fine so not sure why you dredged this thread up to post this now.

    That said, sorry, but your information is not correct. The truth is, many (if not most) motherboards allow both, a card and integrated graphics to run at the same time. This is to support multi-monitor setups. Some systems may automatically disable integrated if a card is detected, but you typically can just go into the BIOS setup menu and enable integrated graphics again, hook up a cable and monitor and be good to go. Don't even need to install additional drivers.

    A simple Google search shows there are dozens of articles showing how to use integrated and graphics card at the same time.
     
    the mekanic likes this.
  30. LJR

    LJR Private First Class

    We obviously have different experiences; perhaps the latest MoBo's do allow use of on-board Video AND a graphics card; the ones I have had to set up were one or the other, but not both at the same time. I guess I msised the part about the OP getting things sorted out; sorry about that.
    One comment, though, about "bleeding off" charge from a power supply when it's turned "off." and unplugged. While current PS's probably do a good job of almost instantly draining any residual charge(s) there are "older'"ATX power supplies that DO benefit from hitting the "power button" to bleed residual charge, but that doesn't necessarily mean they are "bad" or defective. Otherwise, residual charge can be present for up to about 30 seconds after being unplugged. (I have one computer with a PS that can still run a case fan for a second or two right after it's unplugged if I tap the "power" button. Again, it IS an older PS, and undoubtedly not a "major brand." But since it's done that from day 1, and for several years, I have to assume it's normal for THAT type of PS, and not defective.
     
  31. Digerati

    Digerati Major Geek Extraordinaire

    No doubt everyone has different experiences. But allowing both certainly is not just a "latest" motherboard feature.

    Nope. Sorry but not true ASSUMING, of course, the PSU is an ATX compliant PSU in proper working condition.

    One of the primary changes in, and features of the "ATX" Form Factor standard over the older "AT" Form Factor standard is how the front panel power button works. It is simply a remote button that dumps +5V on a specific pin on the motherboard that then signals the PSU to come out of standby and into full output mode. I note the front panel power button on ATX compliant systems does not even connect directly to the power supply.

    This is totally different from the old AT standard that used a big wiring harness that ran directly from the PSU and hardwired to the switch that connected to the front panel (and not the motherboard).

    Also of significance is noting with the ATX Form Factor, that circuit the front panel switch connects to is a "momentary" circuit. That is, when you press the button creating the short that closes that +5VDC circuit, any input from that point on is simply ignored - until you release the switch and press it again. So holding down the switch does nothing - but tire your finger and add a little time for any residual voltages to decay their normal way.

    If you experienced otherwise, it was an AT supply for with those, pressing and holding down the switch did indeed, help the big caps bleed off those voltages. But even then, that was not normal for there "should" have been bleeder resistors in the PSU just for that purpose.

    Now for sure, this is with PCs and not laptops.
     
    the mekanic likes this.
  32. LJR

    LJR Private First Class

    I too well remember the old AT power supplies! Thank goodness THEY are a thing of the past. Yes, they had a true switch (on/off, not momentary) which had to handle several Amperes of current at mains voltage. (120 V U.S.; 240 V in many other places.) the ATX power supplies require only use of a momentary contact to signal the MoBo to turn on the power supply and start the computer. But there were early implementations of the "ATX" form factor and design that might not adhere to current ATX standards. Just MY experience with more than a couple dozen computers, either built, repaired, or upgraded since 1985.:(
     
  33. Digerati

    Digerati Major Geek Extraordinaire

    Nope. Not true. Sorry, but nice try. It seems you are trying to rationalize your initial claim. Even the very first version of the ATX Form Factor worked the way I described above. The case switch connected directly to the motherboard via 2 wires carrying only very low voltage +5VDC. That's it. It's circuit was totally isolated from any large filter caps in the PSU that might (in a faulty PSU) need any extra steps to bleed off any residual voltages.

    The first ATX Form Factor PSUs connected to the motherboard via a 20-pin connector. That's it.

    Later versions used 24-pin connectors (actually 20 + 4) and then 24-pin plus and additional 4 or 8 ATX connector. None of which had anything to do with the case's front panel power switch or that low voltage DC circuit.

    1985? So you are a youngun, huh? Well, to paraphrase Ronald Reagan, I won't hold your obvious youth and lack of experience against you! You can follow the link in my sig to see if I might know a little about the history of the PC hardware and the AT and ATX form factors.
     
  34. LJR

    LJR Private First Class

    I won't argue or debate much further, but I think I already said the ATX supplies (at least those compliant) used a momentary contact to signal the MOTHERBOARD to tell the power supply to turn on the whole computer. the EARLY "ATX" supplies did, indeed have the 20 Position power connector, and not even an option for the "additional" four pin connector, or 24 pin connector to begin with. But what does any of that have to do with how fast (or how slow) the capacitors discharge in the power supply in the design may be somehow "deficient" in bleeder resistors, etc? The fact remains, that with at least some, (usually older) supplies, there can be residual charge in a supply switched "off"" and even unplugged.
     
    Last edited: Dec 1, 2023
  35. Digerati

    Digerati Major Geek Extraordinaire

    :) :D:):D:) Woohoo! Finally! "His eyes open!" (Tamarian for, he understands now! :))

    You are absolutely correct! The fact the ATX supply connects to the motherboard's momentary circuit controlled by the front panel power switch has absolutely nothing to do with how fast (or slow) any residual voltage in the PSUs filter caps decay to safe levels. That is totally true.

    And that is exactly why "hitting the power button" (contrary to your claim above) has zero effect on that residual voltage - which has been my point all along in this whole discussion.

    And the fact it is possible for (potentially deadly!) residual voltages to remain, is one main reason PSUs are not intended to be opened by normal users. There are no "user serviceable parts" inside a PSU. Only trained and qualified techs should open a PSU.

    And for the record, going back 100+ years (200+ years?) those who have studied and worked with capacitors have known all about how they can store voltage long after power has been removed. This is exactly why going back 100+ years, bleeder resistors were used to "bleed off" off those voltages - even in "early", first generation ATX PSUs. My point is, this is not some new technology designers were ignorant of 25 - 30 years ago. They knew all about it and understood fully how to deal with it.

    In fact, way way back when I was in tech school (in 1971-72), we were taught to use a grounding stick (or big screwdriver) to short the capacitor terminals, just to make sure there were no residuals left, before handling large capacitors - whether in circuit, or out. When dealing with 10 - 50,000 watt radio transmitters, getting zapped from a charged cap could ruin your day. ;) We were taught to always ensure CRTs were discharged too as they can hold a charge for days! :eek:

    HOWEVER, as you correctly noted, in some cases, excessive residual voltages may linger. I mean, that's what "residual" means, right? But it is important to understand (and accept!) that sticking around for longer than normal is an indication of a fault!!! A bad resistor, cold-solder joint, who knows? But something ain't right. But only time (not pressing the front panel power switch) will resolve that.

    You mention "design deficiency". That's a possibility too, but if the design is deficient, then it becomes a non-compliance issue. A PSU that does not comply with the ATX standard (either from a design deficiency or component failure) is a totally different ball game. And that can happen today, just as easily as tomorrow, or 20 years ago.

    And BTW, that is NOT just a problem with early generation ATX supplies. Until Man can create perfection 100% of the time, even the best models from the most reputable brands can have a unit that does not work properly, or fails prematurely.

    But design deficiencies and components are exceptions to the rule. And exceptions don't make the rule.

    Last - you bring up a very valid point about this being a potential problem "even unplugged". Bleeder resistors/bleeder circuits work most efficiently and most quickly when they can dump that residual voltage to "Earth" ground. That means through the ground wire in the power cord to the [hopefully] Earth ground in the wall outlet.

    When unplugged, that direct, near-zero resistance path to Earth ground is removed. Those residual voltages will still bleed off to the chassis ground (PSU and computer case) and decay to safe levels, but it will take a little longer, even in ideal (no fault or failure) scenarios.

    Now I must quickly add, users should never put much faith in a $0.25, mass produced, never quality tested, power cord to provide a quality path to Earth ground. Nor should they trust their wall outlet either - without having it tested.

    This is why any formally trained technician worth his salt would never trust their life to the power cord and instead, would use a proper grounding wire/strap tied to a direct path to Earth ground. Just another reason to keep one's fingers out of power supplies.

    So, I think we are on the same page now! Have a good day.
     
  36. LJR

    LJR Private First Class

    You're certainly correct about not trusting the wall socket. My house's original owner (long deceased) was a DIY person, and built the "addition" to the house i'm in; his brother-in-law was an electrical inspector.(You can tell where this is going.) I was finally checking outlets, the "old" part of the house is still "2 wire" outlets, but the three wire (now required)outlets were installed in the kitchen and add-on Rec Room. ALL outlets SEEMED normal, but the bathroom (also a 3-wire outlet) showed NO GROUND, of all places. Then again, there was his brother-in-law...

    Thanks again for the clarifications.
     
  37. Digerati

    Digerati Major Geek Extraordinaire

    LOL Sure can!

    This is why I frequently say in these forums that every home and every computer user should have access to a AC Outlet Tester to ensure the wall outlet is properly wired and grounded to Earth ground. I recommend one with a GFCI (ground fault circuit interrupt) indicator as it can be used to test bathroom and kitchen outlets (outlets near water) too. These testers can be found for your type and voltage outlet, foreign or domestic, (like this one for the UK, or this one for German outlets) at most home improvement stores, or even the electrical department at Wal-Mart. Use it to test all the outlets in the home and if a fault is shown, have it fixed by a qualified electrician.

    ***

    Similar story to yours - I am not a certified "Code Enforcement" officer for the city here, but because of my background in electronics, I did the research to learn and understand the code. My house was built in 1960 when there was still a copper shortage due to military needs during WWII and the Korean War. So much of my house used 2-wire aluminum wiring :(. Fortunately, the kitchen and main bath had already been rewired, but nothing else was.

    My first love in consumer electronics is audiophile grade audio reproduction equipment so I have a pretty decent home theater system too. But the house wiring at the time did nothing to suppress interference, both in the audio and with "noise" on the TV. I was getting more and more frustrated with that.

    Then came a catastrophe that ended up having a nice silver lining. The ceiling of my basement came crashing down one day. Thinking back now, I wonder if the previous owner's brother-in-law installed it? LOL

    Anyway, after surveying the damage and tearing down the rest of the ceiling, I realized all the upstairs floor joists were now totally exposed. Then I realized this would be the perfect time to wire the entire house for Ethernet, the upstairs TV/home theater room and my computer room for surround sound speakers, coax for cable TV throughout, and all the wall outlets with new 3-conductor copper Romex wiring.

    That was a big job made a lot easier due to the fallen ceiling. But well worth it. I now have quality safe wiring, Ethernet throughout the house, cable TV outlets everywhere, and surround sound speakers on the walls with no exposed speaker wires. :)

    Anyway, thanks for listening. Take care.
     

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