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#17
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Fuses don't protect electronics. After something electronic
has failed, a fuse may blow. This so the hardware failure does not result in harm to humans. Do you think a fuse blows to protect electronics? Electricity. First it flows through everything in a circuit. Only then does something blow after everything has been exposed to the same current flow. A 13 amp fuse is going to blow because more than 3 amps flowed through a component rated only for 2 amps? Only when the 2 amp component shorts and starts drawing more like 13 amps. J-Dee wrote: im from UK and every power cable has to have a fuse in UK so suppose it depends where your from. if you use fuses it could well be a problem. "Leythos" wrote: In article , says... Try another powercable it might have a faulty fuse. Power cables don't have fuses, at least not the ones I've seen connected to computers in the US. If you are killing PSU's and you are SURE THE INCOMMING POWER IS GOOD/Clean, then you've got a device inside the computer that's overloading the PSU. You need to determine what part of the PSU is dead - is it a fuse on one of the DC lines or one the AC of the PSU or something else. Your spec's don't seem to need more than 350W would provide, but you could have a shorted/intermittent connection where the screws mounting the motherboard connect to the chassis - many times the installer will not use the proper screw size (screw heads) and will short a trace without knowing it's been done. Disconnect everything, reseat the computers motherboard on the chassis, make sure that every mounting post is accounted for and that none are shorting out traces on the board, same for the screws. I've also seen power leads (for drives) without a cap over them short out on the metal parts of a case and blow a PSU. -- -- remove 999 in order to email me |
#18
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A properly designed power supply cannot be damaged by the
load. A properly designed power supply can have all output wires shorted together. Still the power supply must work just fine after those shorted wires are disconnected. To dump power supplies into a market of computer assemblers, some manufacturers 'forget' to include standard functions. This means a less expensive power supply results in greater profits. Yet many computer assemblers will just swap out power supplies rather than first learn what has failed; or why. The best evidence is a dead body. What inside those power supplies failed. Without that information, no one can tell you why power supplies are failing - other than note discounted supplies are routinely missing essential functions. Functions that even mean power supply failure could damage motherboard and disk drives. A properly manufactured power supply will not damage other computer components. Power supply that is missing essential functions can damage motherboard and RAM. Just another reason why it is foolish to buy power supplies only on price and watts. First thing that power supply must provide is a long list of written and numeric specs. If not, then you are only putting other computer components at risk. Will other electrical appliances damage a power supply? No. Destructive spikes from washing machines or vacuum cleaner is another myth - if the power supply contains minimally essential functions. Will voltage dimming (a sag or brownout) cause power supply failure? Again no if the power supply is properly constructed. If the supply does not retail list for at least $60, then you know it is missing essential function. Such power supplies must also forget to provide any numerical specifications. However do you know those power supplies are damaged. For example, a power supply under too much load will shut off to protect itself. Then others will declare the power supply as defective rather than first learn why the power supply shuts down. A computer assembler should verify power supply output voltages with a multimeter when system is first constructed. Just a few places to start fixing the problem. Again, best evidence is inside the failed power supplies. Information that could result in an immediate and concise answer. Currently we can only post a long list of possible reasons for failure. RobW wrote: Generally speaking the power from the electrical company is good. No other electrical probs. No heavy draw or fluctuation of lights either. I haven't tried a name brand PSU as I have been too frightened it will get fried like the others. Also, up to this point the supplier has been replacing the PSU's under warranty. They will no longer do this, :-) lol. I'm really wondering if it is a problem with the case. Especially since the damage seems to be happening when switching on the machine. Cheers. Rob |
#19
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A properly designed power supply cannot be damaged by the
load. A properly designed power supply can have all output wires shorted together. Still the power supply must work just fine after those shorted wires are disconnected. To dump power supplies into a market of computer assemblers, some manufacturers 'forget' to include standard functions. This means a less expensive power supply results in greater profits. Yet many computer assemblers will just swap out power supplies rather than first learn what has failed; or why. The best evidence is a dead body. What inside those power supplies failed. Without that information, no one can tell you why power supplies are failing - other than note discounted supplies are routinely missing essential functions. Functions that even mean power supply failure could damage motherboard and disk drives. A properly manufactured power supply will not damage other computer components. Power supply that is missing essential functions can damage motherboard and RAM. Just another reason why it is foolish to buy power supplies only on price and watts. First thing that power supply must provide is a long list of written and numeric specs. If not, then you are only putting other computer components at risk. Will other electrical appliances damage a power supply? No. Destructive spikes from washing machines or vacuum cleaner is another myth - if the power supply contains minimally essential functions. Will voltage dimming (a sag or brownout) cause power supply failure? Again no if the power supply is properly constructed. If the supply does not retail list for at least $60, then you know it is missing essential function. Such power supplies must also forget to provide any numerical specifications. However do you know those power supplies are damaged. For example, a power supply under too much load will shut off to protect itself. Then others will declare the power supply as defective rather than first learn why the power supply shuts down. A computer assembler should verify power supply output voltages with a multimeter when system is first constructed. Just a few places to start fixing the problem. Again, best evidence is inside the failed power supplies. Information that could result in an immediate and concise answer. Currently we can only post a long list of possible reasons for failure. RobW wrote: Generally speaking the power from the electrical company is good. No other electrical probs. No heavy draw or fluctuation of lights either. I haven't tried a name brand PSU as I have been too frightened it will get fried like the others. Also, up to this point the supplier has been replacing the PSU's under warranty. They will no longer do this, :-) lol. I'm really wondering if it is a problem with the case. Especially since the damage seems to be happening when switching on the machine. Cheers. Rob |
#20
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I pulled the case and found a fuse that now resembles a used
firecracker which I guess came out of the PSU. (the PSU has a bottom intake fan with large gaps). I am going to take Leythos's suggestion and investigate which fuse on the PSU is blown. I may have to get someone who knows what they are looking at to examine it, :-). I am in Australia and the mains is 240VAC. The power leads have no fuses. Thanks again and I will post the outcome for anyone who is interested. Rob On Mon, 09 May 2005 13:31:15 GMT, Leythos wrote: In article , says... im from UK and every power cable has to have a fuse in UK so suppose it depends where your from. if you use fuses it could well be a problem. I agree then, not knowing where the OP was from, it's a good assumption to guess at the fused power cord if his country requires such. "Leythos" wrote: In article , says... Try another powercable it might have a faulty fuse. Power cables don't have fuses, at least not the ones I've seen connected to computers in the US. If you are killing PSU's and you are SURE THE INCOMMING POWER IS GOOD/Clean, then you've got a device inside the computer that's overloading the PSU. You need to determine what part of the PSU is dead - is it a fuse on one of the DC lines or one the AC of the PSU or something else. Your spec's don't seem to need more than 350W would provide, but you could have a shorted/intermittent connection where the screws mounting the motherboard connect to the chassis - many times the installer will not use the proper screw size (screw heads) and will short a trace without knowing it's been done. Disconnect everything, reseat the computers motherboard on the chassis, make sure that every mounting post is accounted for and that none are shorting out traces on the board, same for the screws. I've also seen power leads (for drives) without a cap over them short out on the metal parts of a case and blow a PSU. -- -- remove 999 in order to email me -- |
#21
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I pulled the case and found a fuse that now resembles a used
firecracker which I guess came out of the PSU. (the PSU has a bottom intake fan with large gaps). I am going to take Leythos's suggestion and investigate which fuse on the PSU is blown. I may have to get someone who knows what they are looking at to examine it, :-). I am in Australia and the mains is 240VAC. The power leads have no fuses. Thanks again and I will post the outcome for anyone who is interested. Rob On Mon, 09 May 2005 13:31:15 GMT, Leythos wrote: In article , says... im from UK and every power cable has to have a fuse in UK so suppose it depends where your from. if you use fuses it could well be a problem. I agree then, not knowing where the OP was from, it's a good assumption to guess at the fused power cord if his country requires such. "Leythos" wrote: In article , says... Try another powercable it might have a faulty fuse. Power cables don't have fuses, at least not the ones I've seen connected to computers in the US. If you are killing PSU's and you are SURE THE INCOMMING POWER IS GOOD/Clean, then you've got a device inside the computer that's overloading the PSU. You need to determine what part of the PSU is dead - is it a fuse on one of the DC lines or one the AC of the PSU or something else. Your spec's don't seem to need more than 350W would provide, but you could have a shorted/intermittent connection where the screws mounting the motherboard connect to the chassis - many times the installer will not use the proper screw size (screw heads) and will short a trace without knowing it's been done. Disconnect everything, reseat the computers motherboard on the chassis, make sure that every mounting post is accounted for and that none are shorting out traces on the board, same for the screws. I've also seen power leads (for drives) without a cap over them short out on the metal parts of a case and blow a PSU. -- -- remove 999 in order to email me -- |
#22
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Tom
Take a look at this.. http://www.littelfuse.com/cgi-bin/r....ION=oNm8TFzMb5 Fuses are not just found in domestic, industrial and automotive power supply lines.. -- Mike Hall MVP - Windows Shell/User http://dts-l.org/goodpost.htm "w_tom" wrote in message ... Fuses don't protect electronics. After something electronic has failed, a fuse may blow. This so the hardware failure does not result in harm to humans. Do you think a fuse blows to protect electronics? Electricity. First it flows through everything in a circuit. Only then does something blow after everything has been exposed to the same current flow. A 13 amp fuse is going to blow because more than 3 amps flowed through a component rated only for 2 amps? Only when the 2 amp component shorts and starts drawing more like 13 amps. J-Dee wrote: im from UK and every power cable has to have a fuse in UK so suppose it depends where your from. if you use fuses it could well be a problem. "Leythos" wrote: In article , says... Try another powercable it might have a faulty fuse. Power cables don't have fuses, at least not the ones I've seen connected to computers in the US. If you are killing PSU's and you are SURE THE INCOMMING POWER IS GOOD/Clean, then you've got a device inside the computer that's overloading the PSU. You need to determine what part of the PSU is dead - is it a fuse on one of the DC lines or one the AC of the PSU or something else. Your spec's don't seem to need more than 350W would provide, but you could have a shorted/intermittent connection where the screws mounting the motherboard connect to the chassis - many times the installer will not use the proper screw size (screw heads) and will short a trace without knowing it's been done. Disconnect everything, reseat the computers motherboard on the chassis, make sure that every mounting post is accounted for and that none are shorting out traces on the board, same for the screws. I've also seen power leads (for drives) without a cap over them short out on the metal parts of a case and blow a PSU. -- -- remove 999 in order to email me |
#23
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Tom
Take a look at this.. http://www.littelfuse.com/cgi-bin/r....ION=oNm8TFzMb5 Fuses are not just found in domestic, industrial and automotive power supply lines.. -- Mike Hall MVP - Windows Shell/User http://dts-l.org/goodpost.htm "w_tom" wrote in message ... Fuses don't protect electronics. After something electronic has failed, a fuse may blow. This so the hardware failure does not result in harm to humans. Do you think a fuse blows to protect electronics? Electricity. First it flows through everything in a circuit. Only then does something blow after everything has been exposed to the same current flow. A 13 amp fuse is going to blow because more than 3 amps flowed through a component rated only for 2 amps? Only when the 2 amp component shorts and starts drawing more like 13 amps. J-Dee wrote: im from UK and every power cable has to have a fuse in UK so suppose it depends where your from. if you use fuses it could well be a problem. "Leythos" wrote: In article , says... Try another powercable it might have a faulty fuse. Power cables don't have fuses, at least not the ones I've seen connected to computers in the US. If you are killing PSU's and you are SURE THE INCOMMING POWER IS GOOD/Clean, then you've got a device inside the computer that's overloading the PSU. You need to determine what part of the PSU is dead - is it a fuse on one of the DC lines or one the AC of the PSU or something else. Your spec's don't seem to need more than 350W would provide, but you could have a shorted/intermittent connection where the screws mounting the motherboard connect to the chassis - many times the installer will not use the proper screw size (screw heads) and will short a trace without knowing it's been done. Disconnect everything, reseat the computers motherboard on the chassis, make sure that every mounting post is accounted for and that none are shorting out traces on the board, same for the screws. I've also seen power leads (for drives) without a cap over them short out on the metal parts of a case and blow a PSU. -- -- remove 999 in order to email me |
#24
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Be careful poking around with/in power supplies, there are
rather large capacitors inside that can hold a lethal charge for some time (weeks perhaps) and they need to be properly discharged before you try to work inside. They will also fry any meter you connect checking for resistance. You can check for a shorted screw by using a DVM set to resistance (ohms) and checking for continuity (0 ohms) where the parts should be grounded together, or infinite resistance between electric circuits and the case. -- The people think the Constitution protects their rights; But government sees it as an obstacle to be overcome. "RobW" wrote in message ... |I pulled the case and found a fuse that now resembles a used | firecracker which I guess came out of the PSU. (the PSU has a bottom | intake fan with large gaps). | I am going to take Leythos's suggestion and investigate which fuse on | the PSU is blown. I may have to get someone who knows what they are | looking at to examine it, :-). | I am in Australia and the mains is 240VAC. | The power leads have no fuses. | Thanks again and I will post the outcome for anyone who is interested. | Rob | | | On Mon, 09 May 2005 13:31:15 GMT, Leythos wrote: | | In article , | says... | im from UK and every power cable has to have a fuse in UK so suppose it | depends where your from. if you use fuses it could well be a problem. | | I agree then, not knowing where the OP was from, it's a good assumption | to guess at the fused power cord if his country requires such. | | | | "Leythos" wrote: | | In article , | says... | Try another powercable it might have a faulty fuse. | | Power cables don't have fuses, at least not the ones I've seen connected | to computers in the US. | | If you are killing PSU's and you are SURE THE INCOMMING POWER IS | GOOD/Clean, then you've got a device inside the computer that's | overloading the PSU. | | You need to determine what part of the PSU is dead - is it a fuse on one | of the DC lines or one the AC of the PSU or something else. | | Your spec's don't seem to need more than 350W would provide, but you | could have a shorted/intermittent connection where the screws mounting | the motherboard connect to the chassis - many times the installer will | not use the proper screw size (screw heads) and will short a trace | without knowing it's been done. | | Disconnect everything, reseat the computers motherboard on the chassis, | make sure that every mounting post is accounted for and that none are | shorting out traces on the board, same for the screws. | | I've also seen power leads (for drives) without a cap over them short | out on the metal parts of a case and blow a PSU. | | -- | -- | | remove 999 in order to email me | | | | -- | |
#25
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Be careful poking around with/in power supplies, there are
rather large capacitors inside that can hold a lethal charge for some time (weeks perhaps) and they need to be properly discharged before you try to work inside. They will also fry any meter you connect checking for resistance. You can check for a shorted screw by using a DVM set to resistance (ohms) and checking for continuity (0 ohms) where the parts should be grounded together, or infinite resistance between electric circuits and the case. -- The people think the Constitution protects their rights; But government sees it as an obstacle to be overcome. "RobW" wrote in message ... |I pulled the case and found a fuse that now resembles a used | firecracker which I guess came out of the PSU. (the PSU has a bottom | intake fan with large gaps). | I am going to take Leythos's suggestion and investigate which fuse on | the PSU is blown. I may have to get someone who knows what they are | looking at to examine it, :-). | I am in Australia and the mains is 240VAC. | The power leads have no fuses. | Thanks again and I will post the outcome for anyone who is interested. | Rob | | | On Mon, 09 May 2005 13:31:15 GMT, Leythos wrote: | | In article , | says... | im from UK and every power cable has to have a fuse in UK so suppose it | depends where your from. if you use fuses it could well be a problem. | | I agree then, not knowing where the OP was from, it's a good assumption | to guess at the fused power cord if his country requires such. | | | | "Leythos" wrote: | | In article , | says... | Try another powercable it might have a faulty fuse. | | Power cables don't have fuses, at least not the ones I've seen connected | to computers in the US. | | If you are killing PSU's and you are SURE THE INCOMMING POWER IS | GOOD/Clean, then you've got a device inside the computer that's | overloading the PSU. | | You need to determine what part of the PSU is dead - is it a fuse on one | of the DC lines or one the AC of the PSU or something else. | | Your spec's don't seem to need more than 350W would provide, but you | could have a shorted/intermittent connection where the screws mounting | the motherboard connect to the chassis - many times the installer will | not use the proper screw size (screw heads) and will short a trace | without knowing it's been done. | | Disconnect everything, reseat the computers motherboard on the chassis, | make sure that every mounting post is accounted for and that none are | shorting out traces on the board, same for the screws. | | I've also seen power leads (for drives) without a cap over them short | out on the metal parts of a case and blow a PSU. | | -- | -- | | remove 999 in order to email me | | | | -- | |
#26
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In article , p51mustang[threeX12]
@xxxhotmail.calm says... Be careful poking around with/in power supplies, there are rather large capacitors inside that can hold a lethal charge for some time (weeks perhaps) and they need to be properly discharged before you try to work inside. They will also fry any meter you connect checking for resistance. Most computer PSU's use CAPS on the DC side and they don't have more than 20+ VDC on most of them, the caps will also discharge in a short amount of time due to the way a PSU is designed. Now, if we were talking the HV circuit of a monitor/TV, I would agree with you completely. As with anything electrical - always disconnect power before working on it and make sure there are no unsafe powers still available. You can check for a shorted screw by using a DVM set to resistance (ohms) and checking for continuity (0 ohms) where the parts should be grounded together, or infinite resistance between electric circuits and the case. The screw, also connected to the chassis, should be a short to the power supply ground, at least the screw eyes in many boards are also grounding pads and will be the same as DC ground for the PSU. In many cases, due to capacitors and other devices you can't get an infinite ohms reading testing like you describe. The best method is to take the motherboard back out of the case and see if it's been improperly installed. Since he mentioned a blown fuse inside the PSU, it would stand to reason (since he said it's not on the AC Side) that he has an intermittent short somewhere - as in a case/screw or wire missing insulation. -- -- remove 999 in order to email me |
#27
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In article , p51mustang[threeX12]
@xxxhotmail.calm says... Be careful poking around with/in power supplies, there are rather large capacitors inside that can hold a lethal charge for some time (weeks perhaps) and they need to be properly discharged before you try to work inside. They will also fry any meter you connect checking for resistance. Most computer PSU's use CAPS on the DC side and they don't have more than 20+ VDC on most of them, the caps will also discharge in a short amount of time due to the way a PSU is designed. Now, if we were talking the HV circuit of a monitor/TV, I would agree with you completely. As with anything electrical - always disconnect power before working on it and make sure there are no unsafe powers still available. You can check for a shorted screw by using a DVM set to resistance (ohms) and checking for continuity (0 ohms) where the parts should be grounded together, or infinite resistance between electric circuits and the case. The screw, also connected to the chassis, should be a short to the power supply ground, at least the screw eyes in many boards are also grounding pads and will be the same as DC ground for the PSU. In many cases, due to capacitors and other devices you can't get an infinite ohms reading testing like you describe. The best method is to take the motherboard back out of the case and see if it's been improperly installed. Since he mentioned a blown fuse inside the PSU, it would stand to reason (since he said it's not on the AC Side) that he has an intermittent short somewhere - as in a case/screw or wire missing insulation. -- -- remove 999 in order to email me |
#28
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Why did you provide a URL for circuit protection devices?
Those are not fuses? Did you assume that because it is a Littelfuse product, then it must be a fuse? Or did you first review the datasheets before posting? Cited are applications for circuit protection devices .... which are not fuses. Circuit protector devices and fuses are not the same device. You have claims a device called TMOV is a fuse. That is wrong. Go back and learn about TMOVs ... "available in 14 and 20 mm disc size with and without a monitor lead (to alert you that the thermal element has opened). The 14 mm parts are rated to 6kA and the 20 mm parts are rated to 10kA." Do you claim these "6,000 and 10,000 amp fuses" would stop electronic damage? Again, fuses blow after the electronic damage has happened so that the human is not put at risk. This being basic electrical knowledge that even a computer assembler should know. "Mike Hall (MS-MVP)" wrote: Take a look at this.. http://www.littelfuse.com/cgi-bin/r....ION=oNm8TFzMb5 Fuses are not just found in domestic, industrial and automotive power supply lines.. |
#29
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Why did you provide a URL for circuit protection devices?
Those are not fuses? Did you assume that because it is a Littelfuse product, then it must be a fuse? Or did you first review the datasheets before posting? Cited are applications for circuit protection devices .... which are not fuses. Circuit protector devices and fuses are not the same device. You have claims a device called TMOV is a fuse. That is wrong. Go back and learn about TMOVs ... "available in 14 and 20 mm disc size with and without a monitor lead (to alert you that the thermal element has opened). The 14 mm parts are rated to 6kA and the 20 mm parts are rated to 10kA." Do you claim these "6,000 and 10,000 amp fuses" would stop electronic damage? Again, fuses blow after the electronic damage has happened so that the human is not put at risk. This being basic electrical knowledge that even a computer assembler should know. "Mike Hall (MS-MVP)" wrote: Take a look at this.. http://www.littelfuse.com/cgi-bin/r....ION=oNm8TFzMb5 Fuses are not just found in domestic, industrial and automotive power supply lines.. |
#30
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And again, fuse designed to blow so that "damage to the
lines/devices" created by component failure does not threaten human life. Any device whose destruction can harm humans will be disconnected by fuses and other equivalent 'one shot' devices. The fuse is not installed to protect hardware. In the process of protecting humans, a fuse may protect some hardware - ie a power cord. But fuses are installed to protect humans. Any protected hardware is incidental. When a fuse blows in a power supply, a failed component often causes that open fuse. Even shorting all power supply outputs would not blow a fuse. The concept is called fold-back current limiting. The fuse is for human protection. It blows typically because a component inside the supply has failed. Furthermore many power supplies don't use fuses. Such human protection is found elsewhere in the power supply design making the fuse unnecessary. Leythos wrote: In article , says... Again, fuses blow after the electronic damage has happened so that the human is not put at risk. This being basic electrical knowledge that even a computer assembler should know. Sorry, the fuse it sized to prevent damage to the lines/devices, not to blow after the device has been damaged (although that may also happen). The fuse is sized to protect some part of the device, be it power lines, transformers, etc.... |
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