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#1
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PSU ?
I've repaired thousands of machines and once in a while have seen a
failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. |
#2
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PSU ?
On Wed, 26 Jun 2019 09:27:25 -0400, philo wrote:
Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. Not well enough to handle a lightning strike. I had a strike kill the mb, ps, and two of three hard drives. The lighting had hit a transformer across the street. Enough power came through to kill that computer. I've since purchased a ups system. While it protects against short term power loss, gives time to shut down safely for longer period losses, and filters out the variations in voltage, etc., I haven't had another lightning strike like that one, so don't know if it is enough to protect from that or not. It also killed all of the incandescent light bulbs that were on at the time, and tripped all of the circuit breakers that had any power going through them. I'd expect the protection in a desktop computer's power supply to protect from minor variations in voltage, but not much else. Regards, Dave Hodgins -- Change to for email replies. |
#3
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PSU ?
philo wrote:
I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. There is a schematic of a basic ATX supply here. http://www.pavouk.org/hw/en_atxps.html That one has overvoltage protection -- it stops Q1 and Q2 from switching and driving transformer T3. So that eventually the ATX supply stops "pushing" into the load. There are no crowbar circuits on the output. The only thing that brings down the voltage, is the load drawing current from the output caps. ATX has nothing to "pull" outputs down. It does not do push pull regulation. It is a push-only circuit, with a feedback loop that says "OK, stop pushing now". If you short a +12V wire to a +5V wire, the +5V output promptly shoots up to +12V, just like that. The two Transorbs on the disk drive, cannot handle sustained abuse, and the +5V Transorb would just burn, until it could no longer protect, and the drive controller is ruined. It depends on how quickly Q1/Q2 drive is removed, how much energy is stored in the +12V output filter cap, as to how many joules can be used to destroy the Transorb (when rails are shorted together). The Transorbs are there to handle "Hot Plug" inductive kick events, not as a means of defense against defective power supplies. Most of the ATX protection is implemented "on the drive side", not "on the load side". The only actual "push-pull" regulator in a computer, is a two amp device running Vtt on the DIMMs. It has to be push-pull, due to the way terminator currents flow. ******* You can find discussions about the "bad" ATX supply here. https://www.badcaps.net/forum/showthread.php?t=9079 The bad "killer" bestec is the ATX-250 12E The hand drawn schematics show them modifying the +5VSB on the 12E, so the part that's been removed, must have been a menace. (Use the "Download Original" button on Postimg to get the full resolution picture.) https://i.postimg.cc/vTLcy1yn/Bestec-ATX-250-12-E.png You'd have to trace further, to find out why an out-of-range +5VSB as part of the supervision circuit, would cause the +5V output to be bad. I thought it was the 12E that could blow hard drives and optical drives and keyboards etc. ******* You can see a basic crowbar circuit here (uses SCR to clamp rail to 0V, causes fuse F1 to blow). These would take a fair amount of space, if every rail needed an SCR, and then the entry fuse (present in each ATX), a slow-blo, would need to be mounted in a cartridge format for easy replacement. https://www.sunpower-uk.com/glossary...ar-protection/ I don't think doing that is common, and neither is it a good idea. I built a crowbar once, for a home made power supply, did a test on it, and the SCR was blown to hell. (The silicon die stayed inside the SCR hex package, but the "tink" sound tells you the silicon die was blown off its substrate.) I never built any more crowbars after that. I thought I'd done the I squared T or whatever calc OK, but the only limiting resistor I had was a length of copper wire. Which apparently wasn't enough. And you can't feasibly add series pass elements, because the on-resistance is too high. Imagine a 12V 100A output with a 50 milliohm series element, say. I squared R would be 10000*0.050 = 500W of heat in the series pass element. The series pass element would need to be better than that, to drop the waste heat level. The efficiency of the supply would be "the pits". The economics of power supply design, dictate the solution. And while there are lots of whacky things you could implement, they probably wouldn't fit in the cubic inches of space available. Most of the time, a failure is within the feedback loop of the supply, and drive can be removed quickly enough that the transient... would be survivable. That might be the premise of operation, and why most of the time nothing bad happens. It's rail to rail short circuits that are a bit harder on the loads connected. and the available energy, is the amount stored in the output caps (up to 5000uF say). A short inside one of those crappy SATA power connectors could do it. Paul |
#4
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PSU ?
On 6/26/19 12:06 PM, David W. Hodgins wrote:
On Wed, 26 Jun 2019 09:27:25 -0400, philo wrote: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. Not well enough to handle a lightning strike. I had a strike kill the mb, ps, and two of three hard drives. The lighting had hit a transformer across the street. Enough power came through to kill that computer. I've since purchased a ups system. While it protects against short term power loss, gives time to shut down safely for longer period losses, and filters out the variations in voltage, etc., I haven't had another lightning strike like that one, so don't know if it is enough to protect from that or not. It also killed all of the incandescent light bulbs that were on at the time, and tripped all of the circuit breakers that had any power going through them. I'd expect the protection in a desktop computer's power supply to protect from minor variations in voltage, but not much else. Regards, Dave Hodgins My machines are on commercial grade UPS' and have survived a direct hit to the incoming power line. What concerns me is the OUTPUT side of the PSU |
#5
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PSU ?
On 6/26/19 12:16 PM, Paul wrote:
philo wrote: I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. There is a schematic of a basic ATX supply here. http://www.pavouk.org/hw/en_atxps.html That one has overvoltage protection -- it stops Q1 and Q2 from switching and driving transformer T3. So that eventually the ATX supply stops "pushing" into the load. There are no crowbar circuits on the output. The only thing that brings down the voltage, is the load drawing current from the output caps. ATX has nothing to "pull" outputs down. It does not do push pull regulation. It is a push-only circuit, with a feedback loop that says "OK, stop pushing now". If you short a +12V wire to a +5V wire, the +5V output promptly shoots up to +12V, just like that. The two Transorbs on the disk drive, cannot handle sustained abuse, and the +5V Transorb would just burn, until it could no longer protect, and the drive controller is ruined. It depends on how quickly Q1/Q2 drive is removed, how much energy is stored in the +12V output filter cap, as to how many joules can be used to destroy the Transorb (when rails are shorted together). The Transorbs are there to handle "Hot Plug" inductive kick events, not as a means of defense against defective power supplies. Most of the ATX protection is implemented "on the drive side", not "on the load side". The only actual "push-pull" regulator in a computer, is a two amp device running Vtt on the DIMMs. It has to be push-pull, due to the way terminator currents flow. ******* You can find discussions about the "bad" ATX supply here. https://www.badcaps.net/forum/showthread.php?t=9079 Â*Â* The bad "killer" bestec is the ATX-250 12E The hand drawn schematics show them modifying the +5VSB on the 12E, so the part that's been removed, must have been a menace. (Use the "Download Original" button on Postimg to get the full resolution picture.) https://i.postimg.cc/vTLcy1yn/Bestec-ATX-250-12-E.png You'd have to trace further, to find out why an out-of-range +5VSB as part of the supervision circuit, would cause the +5V output to be bad. I thought it was the 12E that could blow hard drives and optical drives and keyboards etc. ******* You can see a basic crowbar circuit here (uses SCR to clamp rail to 0V, causes fuse F1 to blow). These would take a fair amount of space, if every rail needed an SCR, and then the entry fuse (present in each ATX), a slow-blo, would need to be mounted in a cartridge format for easy replacement. https://www.sunpower-uk.com/glossary...ar-protection/ I don't think doing that is common, and neither is it a good idea. I built a crowbar once, for a home made power supply, did a test on it, and the SCR was blown to hell. (The silicon die stayed inside the SCR hex package, but the "tink" sound tells you the silicon die was blown off its substrate.) I never built any more crowbars after that. I thought I'd done the I squared T or whatever calc OK, but the only limiting resistor I had was a length of copper wire. Which apparently wasn't enough. And you can't feasibly add series pass elements, because the on-resistance is too high. Imagine a 12V 100A output with a 50 milliohm series element, say. I squared R would be 10000*0.050 = 500W of heat in the series pass element. The series pass element would need to be better than that, to drop the waste heat level. The efficiency of the supply would be "the pits". The economics of power supply design, dictate the solution. And while there are lots of whacky things you could implement, they probably wouldn't fit in the cubic inches of space available. Most of the time, a failure is within the feedback loop of the supply, and drive can be removed quickly enough that the transient... would be survivable. That might be the premise of operation, and why most of the time nothing bad happens. It's rail to rail short circuits that are a bit harder on the loads connected. and the available energy, is the amount stored in the output caps (up to 5000uF say). A short inside one of those crappy SATA power connectors could do it. Â*Â* Paul I did not specifically see MOVs on the outputs. When I was working in industrial electronics I added them to most everything. I may have to add MOV's to my own equipment if there I can't find a manufacturer that does so. |
#6
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PSU ?
On 6/26/2019 9:27 AM, philo wrote:
I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. I, too, have had one PSU misbehave and take out a hard drive but that was a very long time ago and with a no-name PSU. I learned my lesson after that and now use nothing but Seasonic supplies, at least in situations where they make a supply that will fit. Right now the only computers I own that don't have Seasonic are my Shuttle cubes and they are tied to the form-specific equipment. Luckily the Shuttle PSUs have proven to be faultless also. I don't know of any maker that installs crowbar protection on their supplies although I believe it would take little more than a high-current SCR a Zener diode and a few other passive components to work the magic. |
#7
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PSU ?
On 6/30/19 9:29 AM, John McGaw wrote:
On 6/26/2019 9:27 AM, philo wrote: I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. I, too, have had one PSU misbehave and take out a hard drive but that was a very long time ago and with a no-name PSU. I learned my lesson after that and now use nothing but Seasonic supplies, at least in situations where they make a supply that will fit. Right now the only computers I own that don't have Seasonic are my Shuttle cubes and they are tied to the form-specific equipment. Luckily the Shuttle PSUs have proven to be faultless also. I don't know of any maker that installs crowbar protection on their supplies although I believe it would take little more than a high-current SCR a Zener diode and a few other passive components to work the magic. All I know is that for industrial use MOV's were everywhere and they worked. That said, If I try my own modifications I'll do it on a non-critical machine first. Will also look into Seasonic PSU's, thanks |
#8
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PSU ?
On 6/30/2019 7:00 PM, philo wrote:
On 6/30/19 9:29 AM, John McGaw wrote: On 6/26/2019 9:27 AM, philo wrote: I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. I, too, have had one PSU misbehave and take out a hard drive but that was a very long time ago and with a no-name PSU. I learned my lesson after that and now use nothing but Seasonic supplies, at least in situations where they make a supply that will fit. Right now the only computers I own that don't have Seasonic are my Shuttle cubes and they are tied to the form-specific equipment. Luckily the Shuttle PSUs have proven to be faultless also. I don't know of any maker that installs crowbar protection on their supplies although I believe it would take little more than a high-current SCR a Zener diode and a few other passive components to work the magic. All I know is that for industrial use MOV's were everywhere and they worked. That said, If I try my own modifications I'll do it on a non-critical machine first. Will also look into Seasonic PSU's, thanks Oh, I've use MOVs for various things but the problem is that they aren't all that precise. Great at absorbing and dissipating lots of power but the voltage at which they operate are vague at best. I've used bushels of them protecting broadcast and computer equipment from line transients but I'd be hard pressed to set them up to protect a 12V circuit from going above 13.5V where damage to a hard drive might be expected to begin. A glance at some spec sheets suggests that using a 12V MOV the clamping voltage might be 40+. But if you decide to give it a shot and make it work well, please let up know. |
#9
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PSU ?
On 7/1/19 9:59 AM, John McGaw wrote:
On 6/30/2019 7:00 PM, philo wrote: On 6/30/19 9:29 AM, John McGaw wrote: On 6/26/2019 9:27 AM, philo wrote: I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. I, too, have had one PSU misbehave and take out a hard drive but that was a very long time ago and with a no-name PSU. I learned my lesson after that and now use nothing but Seasonic supplies, at least in situations where they make a supply that will fit. Right now the only computers I own that don't have Seasonic are my Shuttle cubes and they are tied to the form-specific equipment. Luckily the Shuttle PSUs have proven to be faultless also. I don't know of any maker that installs crowbar protection on their supplies although I believe it would take little more than a high-current SCR a Zener diode and a few other passive components to work the magic. All I know is that for industrial use MOV's were everywhere and they worked. That said, If I try my own modifications I'll do it on a non-critical machine first. Will also look into Seasonic PSU's, thanks Oh, I've use MOVs for various things but the problem is that they aren't all that precise. Great at absorbing and dissipating lots of power but the voltage at which they operate are vague at best. I've used bushels of them protecting broadcast and computer equipment from line transients but I'd be hard pressed to set them up to protect a 12V circuit from going above 13.5V where damage to a hard drive might be expected to begin. A glance at some spec sheets suggests that using a 12V MOV the clamping voltage might be 40+. But if you decide to give it a shot and make it work well, please let up know. Well, if I install MOV's and never have a HD burn out again it still does not prove they did the trick. I have a few other ideas though. The person I know who lost two drives had a RAID 1 (mirrored) so he thought he was safe. Now I see that one possible way to build a reliable machine would be to have each drive powered by a completely separate supply and probably from a different manufacturer. That said, it's been my experience in life that no matter what you plan for, something else is going to happen! Maybe I'll just continue doing backups because to reinstall the OS is not a big deal...all that's important it the data |
#10
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PSU ?
On 7/1/2019 11:20 AM, philo wrote:
On 7/1/19 9:59 AM, John McGaw wrote: On 6/30/2019 7:00 PM, philo wrote: On 6/30/19 9:29 AM, John McGaw wrote: On 6/26/2019 9:27 AM, philo wrote: I've repaired thousands of machines and once in a while have seen a failed power supply take out a motherboard. Only once though have I seen the hard drives taken out. It was with a good quality supply and I thought it was just a very odd fluke. Last night I talked to someone who had also had it happen ,....so my question is: Does any manufacturer have a supply with fully surge-protected OUTPUT? I assumed they all did. I, too, have had one PSU misbehave and take out a hard drive but that was a very long time ago and with a no-name PSU. I learned my lesson after that and now use nothing but Seasonic supplies, at least in situations where they make a supply that will fit. Right now the only computers I own that don't have Seasonic are my Shuttle cubes and they are tied to the form-specific equipment. Luckily the Shuttle PSUs have proven to be faultless also. I don't know of any maker that installs crowbar protection on their supplies although I believe it would take little more than a high-current SCR a Zener diode and a few other passive components to work the magic. All I know is that for industrial use MOV's were everywhere and they worked. That said, If I try my own modifications I'll do it on a non-critical machine first. Will also look into Seasonic PSU's, thanks Oh, I've use MOVs for various things but the problem is that they aren't all that precise. Great at absorbing and dissipating lots of power but the voltage at which they operate are vague at best. I've used bushels of them protecting broadcast and computer equipment from line transients but I'd be hard pressed to set them up to protect a 12V circuit from going above 13.5V where damage to a hard drive might be expected to begin. A glance at some spec sheets suggests that using a 12V MOV the clamping voltage might be 40+. But if you decide to give it a shot and make it work well, please let up know. Well, if I install MOV's and never have a HD burn out again it still does not prove they did the trick. I have a few other ideas though. The person I know who lost two drives had a RAID 1 (mirrored) so he thought he was safe. Now I see that one possible way to build a reliable machine would be to have each drive powered by a completely separate supply and probably from a different manufacturer. That said, it's been my experience in life that no matter what you plan for, something else is going to happen! Maybe I'll just continue doing backups because to reinstall the OS is not a big deal...all that's important it the data There is no substitute for backups. No matter what. I am quite paranoid about protecting my primary machine. As I write this it is doing its monthly backup which will go into the bank's vault this afternoon -- there are three portable drives cycling through these backups. Every evening it does a full backup to my elderly WHS and at 1AM it did a backup to one of my redundant Drobo NAS units. Oh, and as the mood strikes me I do a system disk image to a series of portable SSD units that are kept in a media safe here at home in case I need to restore a bootable image. I have been burned too many times by seemingly random glitches. This level of backup would be overkill for most people but I believe that any user who doesn't have at least two levels of backup, one of them offsite but under his/her direct control, is a fool and probably deserves whatever comes their way. |
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