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#21
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Even in the very first IBM PC, power supply included that
voltage monitoring function (that is now part of the single IC). A function completely different from the overvoltage protection circuit - which was also in that IBM PC. Some power supply controller failures can cause overvoltage. Totally unacceptable 30 years ago as today. The crowbar (or equivalent) is required today as it was 30 years ago on switch mode power supplies. Even the Intel spec (which is only for switch mode power supplies) says The overvoltage sense circuitry and reference shall reside in packages that are separate and distinct from the regulator control circuitry and reference. No single point fault shall be able to cause a sustained overvoltage condition on any or all outputs. The supply shall provide latch-mode overvoltage protection as defined below. Nothing new in this requirement. However when dumping product into a marketplace dominated by 'bean counter' mentalities, then profits are just too great. How to suspect a defective power supply? No long list of numerical specification and no specific listing of overvoltage protection? Then it is a power supply for the market of 'bean counting' computer assemblers. That schematic is further proof that many power supplies are missing essential functions. Some power supplies fail and then destroy computer peripherals. A failure directly traceable to a human who buys on price rather than learn basic electrical principles. In a market where so many 'experts' don't even know how how electricity works, then many clone computers do have $25 power supplies. When a supply fails due to a manufacturing defect, that 'computer assembler' instead blames disk drive and motherboard damage on mythical transients. Why? Most don't even know what electronic part has failed; let alone know why. Better to just blame something mythical that others will quickly believe. Does the power supply provide a long list of numerical specifications? Many do not provide specs which means essential overvoltage protection is not required. Its called dumping. Made profitable by computer assemblers don't even understand why component manufacturers should provide numerical specs. Specs from a responsible power supply manufacturer are quite long. Abridged election from one responsible power supply vendor whose supply could never sell for $25 retail - because it includes essential functions: Specification compliance: ATX 2.03 & ATX12V v1.1 Short circuit protection on all outputs Over voltage protection Over power protection 100% hi-pot test Efficiency; 100-120VAC and full range: 65% EMI/RFI compliance: CE, CISPR22 & FCC part 15 class B Safety compliance: VDE, TUV, D, N, S, Fi, UL, C-UL & CB Hold up time, full load: 16ms. typical Does your power supply specifically, with numbers, make these claims? Why not? Symptoms of a supply that does not have these essential functions; which can create future computer failures. Demonstrated are how those with minimal education recommend and buy power supplies. Schematics from Franc Zabkar only demonstrate that power supplies without essential functions are being manufactured. Some computer failures can be created by power supplies missing these essential functions. Many computer assemblers may then invent other suspects to blame. If a power supply failure coincides with disk drive damage, then first look for a missing overvoltage protection circuit. Franc Zabkar wrote: The chip senses all the rails, including the negative ones, and shuts down the oscillator if there is a fault condition. No oscillator means no output. AFAICS, there is no need to crowbar the affected rail(s). Pins 3,4, and 6 provide the OV functions. Pin 5 is probably equivalent in function to the OPP (over power protection) pin of the SG6105. ... Crowbar SCRs/zeners were used in the old days with linear supplies, but these days most supplies are switchmode. The crowbar would protect the load from a shorted pass transistor by blowing a fuse, but IMO a switchmode supply doesn't really need such protection, unless there is a possibility that the OV sense circuitry itself could fail. ... The chip's datasheet states that the chip performs under- and overvoltage sensing/protection, as well as overpower and short circuit protection. The overpower pin (OPP) requires some inexpensive external components including a diode and some passives. ... True, but I suspect Intel is just playing it safe. I have no problem with a single-chip PSU, especially if the cost savings could be applied to properly rated parts, particularly the capacitors, diodes, and magnetics on the DC side. ... I don't recall seeing any such expensive components in any PC SMPS. All the PSUs I've seen shut down the PWM controller if there is an OV condition, but then I've only ever seen generic PSUs. What components do the more expensive branded PSUs use? |
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On Mon, 11 Apr 2005 19:35:21 -0400, w_tom put
finger to keyboard and composed: Even in the very first IBM PC, power supply included that voltage monitoring function (that is now part of the single IC). A function completely different from the overvoltage protection circuit - which was also in that IBM PC. Some power supply controller failures can cause overvoltage. Totally unacceptable 30 years ago as today. The crowbar (or equivalent) is required today as it was 30 years ago on switch mode power supplies. Even the Intel spec (which is only for switch mode power supplies) says The overvoltage sense circuitry and reference shall reside in packages that are separate and distinct from the regulator control circuitry and reference. No single point fault shall be able to cause a sustained overvoltage condition on any or all outputs. The supply shall provide latch-mode overvoltage protection as defined below. I understand that separating the two functions (OVS and OVP) gives added security, but I can't see the need for a brute-force approach to OVP. By this I mean that it is not necessary to clamp the output with an expensive high-current zener or SCR - one can much more elegantly achieve the same end, and still comply with Intel's spec, by turning off the PWM controller, or by turning off its drive transistors. See this DTK PSU which implements OVS, OVP and OPP with about $2 worth of parts: http://www.pavouk.comp.cz/hw/en_atxps.html I have a 1000W minicomputer SMPS whose control module senses the output and shuts off the oscillator in the event of an OV fault. There are no expensive OVP parts, and this is in an SMPS that has 4 or 5 screw terminal capacitors the size of soft drink cans, stud mounted diodes on massive heatsinks, four TO3 chopper transistors, and an AC fan. The +5V cables (+5V @ 150A) are thick enough to start my car. Nothing new in this requirement. However when dumping product into a marketplace dominated by 'bean counter' mentalities, then profits are just too great. How to suspect a defective power supply? No long list of numerical specification and no specific listing of overvoltage protection? Then it is a power supply for the market of 'bean counting' computer assemblers. Some TV sets use 130V protection zeners (eg R2M, R2KY, $1.85 retail) on their 100-115V supply rails. These designs have no OVS. Ironically it appears that the designers have chosen this sledgehammer approach because it costs *less* than OVS. I'm not really comfortable with such a design because its success depends on the failure mode of the protection device. IME the zener always fails SC, and therefore protects the TV, but if it fails OC (unlikely, but possible), then there is no protection at all. Killing the oscillator would be much safer. In fact, HV protection and beam current limiting is usually implemented by shutting down the horizontal oscillator. I guess a comparable analogy may be MOVs in "surge protected" power boards. They may sacrificially absorb the first surge, but thereafter they are useless. That schematic is further proof that many power supplies are missing essential functions. Sorry, I don't see it. You state that the original IBM supplies had an OVP circuit, but you don't elaborate. How exactly did they do this? I have the original IBM AT Tech Ref Manual but it doesn't adequately spell out the PSU spec. Can you recommend one upmarket PSU that handles OVP by brute-forcing the output(s)? Some power supplies fail and then destroy computer peripherals. True. I witnessed a discussion at aus.electronics where an SMPS failed in such a manner that AC leaked into the DC side of the switchmode transformer, causing catastrophic damage to the PC. I suggested that an external crowbar circuit could provide protection against such disasters but the responses were negative. A failure directly traceable to a human who buys on price rather than learn basic electrical principles. In a market where so many 'experts' don't even know how how electricity works, then many clone computers do have $25 power supplies. What I find hard to comprehend is how even the upmarket ATX PSUs can deliver their claimed power given the relative size of the components in my 1000W SMPS. For example, when comparing the mains filter caps, one is the size of a Coke can, the other is smaller than a C size battery. Has technology really improved that much? - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
#23
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You are assuming a power supply controller will see all
failures and then shutdown accordingly. What happens when controller's feedback fails? A feedback circuit that will be discussed again below. Power supply controller outputs more power trying to raise a voltage that never rises. IOW power supply has output excessive and destructive voltages. Just another reason why "separate and distinct" overvoltage protection has been required 30 years ago as it still is required today. Neither you nor I care how a particular power supply meets this 'well proven to be necessary' OVP function. We don't even care if the function uses a simple and easily constructed crowbar or uses something different. The point remains a power supply must provide that defined function. Schematic from electro-tech.narod.ru quite obviously violates the industry requirement. It has no overvoltage protection. It demonstrates how power supplies are sold for well under $60 retail. They forget to include essential functions such as OVP. That supply from http://electro-tech.narod.ru is designed to be dumped into a market driven by 'bean counter' engineering. Provided were numeric specs for a supply that does provide the OVP circuit. Back to the original point. Properly designed supply does not and can not sell for $25 retail. So how do others sell power supplies for $25 retail? They forget to include required and necessary functions such as Overvoltage Protection. Is this done by a crowbar circuit or by some other means? Neither you nor I care. Industry standards demand that OVP function exist for 'long proven' necessary reasons. Some supplies do provide such functions. But these minimally acceptable supplies cannot sell for $25 retail - again repeating the bottom line point. In the meantime, that DTK PSU from www.pavouk.comp.cz violates another essential function. The power supply must provide galvanic isolation of at least 1000 volts. Therefore the "Feedback" circuit must contain an optocoupler or something equivalent. The DTK PSU has no such isolation. It violates another industry standard. And so another essential function would be 'forgotten'. Earlier a power supply controller would output overvoltage because the feedback circuit failed. Controller never knew it was outputting excessive voltage. What feedback components? Same optocoupler that is required with galvanic isolation. Just another missing specification to sell at $25. Again the point. Power supplies missing essential functions and routinely dumped into the market because so many computer assemblers don't even have basic electrical knowledge; never learned about galvanic isolation, overvoltage protection, feedback current limiting, or overpower protection. When a computer assembler looks only at power and price, then a game of specmanship is afoot. For example, a Dell or HP power supply may claim only 250 watts. The 'bean counting' computer assembler then claims that is woefully too small. And yet if the same power supply was being marketed by others to computer assemblers, then suddenly the same supply is rated at 375 watts. Why? They don't list the output power. Rated is maximum power that a power supply might consume. The 'bean counting' computer assembler then declares the HP and Dell supplies are undersized. It gets even more interesting. A power supply must be completely shorted out and still must not be damaged. And yet here are power supplies, designed for a 'bean counter' market, that self destruct even before reaching 100% load: http://www6.tomshardware.com/howto/0...021/index.html First thing to look for in any power supply: if the supply manufacturer does not provide a long list of numerical specs, then bet it is a scam. More responsible power supply manufacturers provide numerous numerical specs. One need not even know what those specs mean. Just having written numerical specs is a first requirement. Manufacturer commits; says to the 1% who know technology that this supply does provide these functions. However a manufacturer who is dumping inferior supplies into a market of computer assemblers must disempower the 1%. He must provide no written specifications. Then a knowledgeable 1% cannot warn the other 99% of a defective product. Welcome to a world where so many power supplies don't provide specs and are then recommended based only on the price and watts. #1 requirement for a power supply: it must provide a long list of numeric specs. If that power supply does not specifically state overvoltage protection, then another essential function is missing. We care less how he provides overvoltage protection. We care more that he claims to provide OVP. That missing function demonstrates why so many supplies sell for only $25 and $40 full retail. Franc Zabkar wrote: On Mon, 11 Apr 2005 19:35:21 -0400, w_tom put finger to keyboard and composed: ... I understand that separating the two functions (OVS and OVP) gives added security, but I can't see the need for a brute-force approach to OVP. By this I mean that it is not necessary to clamp the output with an expensive high-current zener or SCR - one can much more elegantly achieve the same end, and still comply with Intel's spec, by turning off the PWM controller, or by turning off its drive transistors. See this DTK PSU which implements OVS, OVP and OPP with about $2 worth of parts: http://www.pavouk.comp.cz/hw/en_atxps.html I have a 1000W minicomputer SMPS whose control module senses the output and shuts off the oscillator in the event of an OV fault. There are no expensive OVP parts, and this is in an SMPS that has 4 or 5 screw terminal capacitors the size of soft drink cans, stud mounted diodes on massive heatsinks, four TO3 chopper transistors, and an AC fan. The +5V cables (+5V @ 150A) are thick enough to start my car. ... Some TV sets use 130V protection zeners (eg R2M, R2KY, $1.85 retail) on their 100-115V supply rails. These designs have no OVS. Ironically it appears that the designers have chosen this sledgehammer approach because it costs *less* than OVS. I'm not really comfortable with such a design because its success depends on the failure mode of the protection device. IME the zener always fails SC, and therefore protects the TV, but if it fails OC (unlikely, but possible), then there is no protection at all. Killing the oscillator would be much safer. In fact, HV protection and beam current limiting is usually implemented by shutting down the horizontal oscillator. I guess a comparable analogy may be MOVs in "surge protected" power boards. They may sacrificially absorb the first surge, but thereafter they are useless. ... Sorry, I don't see it. You state that the original IBM supplies had an OVP circuit, but you don't elaborate. How exactly did they do this? I have the original IBM AT Tech Ref Manual but it doesn't adequately spell out the PSU spec. Can you recommend one upmarket PSU that handles OVP by brute-forcing the output(s)? ... True. I witnessed a discussion at aus.electronics where an SMPS failed in such a manner that AC leaked into the DC side of the switchmode transformer, causing catastrophic damage to the PC. I suggested that an external crowbar circuit could provide protection against such disasters but the responses were negative. ... What I find hard to comprehend is how even the upmarket ATX PSUs can deliver their claimed power given the relative size of the components in my 1000W SMPS. For example, when comparing the mains filter caps, one is the size of a Coke can, the other is smaller than a C size battery. Has technology really improved that much? - Franc Zabkar |
#24
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On Tue, 12 Apr 2005 07:05:18 -0400, w_tom put
finger to keyboard and composed: You are assuming a power supply controller will see all failures and then shutdown accordingly. I did write that "I understand that separating the two functions (OVS and OVP) gives added security", so I understand that there are some caveats with a single-chip approach. What happens when controller's feedback fails? In most cases the OVS circuitry will detect an OV condition and shut down the oscillator. I've actually seen such faults in other PSUs, eg when optocouplers or feedback transformers or sense resistors go OC. One potential problem with single-chip solutions is if the internal reference voltage is shared by both the OVS logic and the PWM regulator. In such cases a fault in the voltage reference may cause catastrophic damage. Having said that, it may still be possible to separate these two functions within the same IC. In any case the DTK circuit I alluded to *does* separate these functions and *does* comply with Intel's spec. And it does this at the cost of a few small-signal transistors, diodes, and passives. In fact the BOM for the OV, PG, and PWM circuits would cost about $1 or $2. http://focus.ti.com/docs/prod/folders/print/tl494.html $0.23 /1000 http://focus.ti.com/docs/prod/folders/print/lm393.html $0.16 /1000 Neither you nor I care how a particular power supply meets this 'well proven to be necessary' OVP function. We don't even care if the function uses a simple and easily constructed crowbar or uses something different. The point remains a power supply must provide that defined function. Schematic from electro-tech.narod.ru quite obviously violates the industry requirement. It has no overvoltage protection. It *does* have OVP. It's just that the implementation does not appear to rigidly follow Intel's spec. For example, if I interfere with the +5V feedback by removing R62 from pin 14, the output voltages will rise to a point where the OVS pins (3,4,6) will trigger a shutdown of the oscillator. Provided were numeric specs for a supply that does provide the OVP circuit. Specs can lie, or at least be deceiving. A high price does not guarantee quality or spec compliance. Is this done by a crowbar circuit or by some other means? Neither you nor I care. On the contrary, I do. At the very least, knowing how a certain function is implemented can explain any differences in price. For example, if each of the major rails were shunted by high current SCRs or protection zeners, then one could expect to pay a much higher price. OTOH, if OVS and OVP were implemented with 50c ICs, then one would not expect such functions to impact noticeably on the overall cost. In the absence of specific examples from you, I'm left to examine various PSUs at this website: http://terasan.okiraku-pc.net Unfortunately the site is in Japanese, but there is just enough info to ascertain the inner workings of both low-end and high-end ATX PSUs. For example, Antec's TruePower 550 is pictured and described he http://terasan.okiraku-pc.net/dengen/no57/ The ICs of interest are the UC3844 PWM regulator and the TPS3510 PSU supervisor: http://www.st.com/stonline/books/pdf/docs/4299.pdf http://focus.ti.com/lit/ds/symlink/tps3510.pdf The costs a http://focus.ti.com/docs/prod/folder...t/tps3510.html $0.45 /1000 http://focus.ti.com/docs/prod/folders/print/uc3844.html $0.80 /1000 The TPS3510 IC implements OVS, UVS, OVP, UVP, and PG. I suspect its Fault Protection Output pin controls the UC3844 regulator. There appear to be no other OVP parts. Another manufacturer, PC Power & Cooling, uses the TPS5510 supervisor IC in its Turbo-Cool 450ATX: http://terasan.info/dengen/no041/ http://focus.ti.com/lit/ds/symlink/tps5510.pdf Industry standards demand that OVP function exist for 'long proven' necessary reasons. Some supplies do provide such functions. But these minimally acceptable supplies cannot sell for $25 retail - again repeating the bottom line point. That may be true, but if we were to use your definition of OVP, then some, if not all, branded PSUs do not provide this function either. In the meantime, that DTK PSU from www.pavouk.comp.cz violates another essential function. The power supply must provide galvanic isolation of at least 1000 volts. Therefore the "Feedback" circuit must contain an optocoupler or something equivalent. The DTK PSU has no such isolation. It violates another industry standard. And so another essential function would be 'forgotten'. The regulator and the feedback circuit exist on the same side of the PSU, ie on the DC side. Therefore no "galvanic isolation" is required between the two. In any case, isolation between the AC and DC sections is provided by transformers, at least when high currents are involved. AFAICS, cheap optocouplers are only used in the 5VSB circuit, if at all. In the DTK case, no special feedback is required in the 5VSB section because the 78L05 linear regulator doesn't require it. OTOH, the LC-B250ATX uses an optically isolated TL431 voltage reference to achieve the same end. The Antec Truepower PSUs appear to do it this way, too. All three PSU designs are "galvanically isolated" where needed. When a computer assembler looks only at power and price, then a game of specmanship is afoot. That works both ways. Ignorant people assume that a higher price means higher quality. They have never heard of "badge engineering". That's where an up-market vendor/manufacturer rebadges a down-market product and extracts a price premium by leveraging his reputation rather than his technical expertise. For example, a Dell or HP power supply may claim only 250 watts. The 'bean counting' computer assembler then claims that is woefully too small. And yet if the same power supply was being marketed by others to computer assemblers, then suddenly the same supply is rated at 375 watts. Why? They don't list the output power. Rated is maximum power that a power supply might consume. The 'bean counting' computer assembler then declares the HP and Dell supplies are undersized. I have to agree. In fact my own measurements lead me to believe that typical Athlon and P4 systems will never draw more than 150W. It gets even more interesting. A power supply must be completely shorted out and still must not be damaged. And yet here are power supplies, designed for a 'bean counter' market, that self destruct even before reaching 100% load: http://www6.tomshardware.com/howto/0...021/index.html The first thing that caught my eye was this: "We've ... now decided to tackle this volatile subject with testing of 21 different, high-end power supplies in the THG lab in Munich, Germany. In spite of the high end-user retail prices, our lab technicians were surprised by the test results. No fewer than 6 power supplies struggled under full load: 3 of the candidates simply went up in smoke, while the other 3 shut down prematurely." It seems that price, specs and reputation are no guarantee of performance. ;-) This also caught my eye: "Our attempt to test the Noise Magic power supply had disastrous consequences. This is a modified Enermax unit fitted with a Papst fan. It stopped working after one minute. When we tried to switch it back on again after a suitable delay, it simply burned out." I would have thought that even a badge engineered Enermax was not a "bean counter's" PSU ;-) Anyway, you have introduced a new subject, namely overload protection. OVP is cheap to implement, but sensing current is more difficult than sensing voltage, so I would expect that many manufacturers would take shortcuts here. The aforementioned LC and DTK PSUs both sense a voltage at the drive transformer, whereas other PSUs monitor the current flow in the chopper transistor(s). I'm not sure that's the way the Antec 550W PSU does it, but its UC3844 PWM controller *does* have a current sense pin. The application circuit shows this pin connected to a current transformer. My 1000W minicomputer PSU also uses a current transformer in the chopper circuit to indirectly sense the load current. I suspect that the OPP circuits in cheaper PSUs (such as the LC and DTK) would be able to respond correctly to dead shorts, but not necessarily to overloads. - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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"U. Cortez" said
I believe a power surge toasted my power supply the other day, so I replaced it with a new 350W ATX PSU. After removing the burnt psu, I screwed the new psu into the case, hooked the ATX power supply to the motherboard, and hooked up power for various components (HD's, CD-ROM's). The motherboard's pilot light turns on to signify that it's getting power, but when I press the case's power button... nothing. No fans, no sound, no disk spinning, no signs of life at all (besides that pilot light being on). Am I forgetting something? I inspected all the components (and the motherboard and cpu) and none of them appear (or smell) to have been damaged. Where do I go from here? Any help would be appreciated. Motherboard: DFI AK70 (AMD 750 cpu). -U. PS, forgive the cross-post -- I don't have a news host and google is giving me errors when I try to post to some of these groups individually. |
#26
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Jon wrote:
"U. Cortez" said I believe a power surge toasted my power supply the other day, so I replaced it with a new 350W ATX PSU. After removing the burnt psu, I screwed the new psu into the case, hooked the ATX power supply to the motherboard, and hooked up power for various components (HD's, CD-ROM's). The motherboard's pilot light turns on to signify that it's getting power, but when I press the case's power button... nothing. No fans, no sound, no disk spinning, no signs of life at all (besides that pilot light being on). Am I forgetting something? I inspected all the components (and the motherboard and cpu) and none of them appear (or smell) to have been damaged. Where do I go from here? Any help would be appreciated. Motherboard: DFI AK70 (AMD 750 cpu). -U. PS, forgive the cross-post -- I don't have a news host and google is giving me errors when I try to post to some of these groups individually. If your MB has the 4-pin (square) auxiliary power connector, and you haven't connected it, you will get that result. Another possibility is that, while changing the PS, you accidentally disconnected the power button connector. It's small and easy to pull off its header. -- The e-mail address in our reply-to line is reversed in an attempt to minimize spam. Our true address is of the form . |
#27
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On Thu, 01 Sep 2005 04:00:04 GMT, in comp.sys.ibm.pc.hardware.systems,
CJT wrote: Jon wrote: "U. Cortez" said I believe a power surge toasted my power supply the other day, so I replaced it with a new 350W ATX PSU. After removing the burnt psu, I screwed the new psu into the case, hooked the ATX power supply to the motherboard, and hooked up power for various components (HD's, CD-ROM's). The motherboard's pilot light turns on to signify that it's getting power, but when I press the case's power button... nothing. No fans, no sound, no disk spinning, no signs of life at all (besides that pilot light being on). Am I forgetting something? I inspected all the components (and the motherboard and cpu) and none of them appear (or smell) to have been damaged. Where do I go from here? Any help would be appreciated. Motherboard: DFI AK70 (AMD 750 cpu). -U. PS, forgive the cross-post -- I don't have a news host and google is giving me errors when I try to post to some of these groups individually. If your MB has the 4-pin (square) auxiliary power connector, and you haven't connected it, you will get that result. Another possibility is that, while changing the PS, you accidentally disconnected the power button connector. It's small and easy to pull off its header. A mistake people make every now and then (including myself, and I've assembled lots of computers) is to set the FDD power connector one step to the side (only connecting three of the four pins), and this will cause a shortcut. Another possibility is that something else is dead too. All defects aren't visible to the naked eye... Disconnect all power cables except the one to the motherboard, and also disconnect the IDE and FDD cables (a defective drive can prevent a computer from starting). Then try to start the comp again. If it works now, start reconnecting components one by one, and do a test start between each... If it doesn't start even with all drives etc disconnected, your mobo might be fried. Or maybe your new PSU is defective too. Or something else... -- May all spammers die in horrible pains! Wanna e-mail me? Well, peter_e is correct, but the rest is obviously bogus... Try algonet in the .se TLD instead. |
#28
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"Peter Emanuelsson" wrote in message ... On Thu, 01 Sep 2005 04:00:04 GMT, in comp.sys.ibm.pc.hardware.systems, CJT wrote: Jon wrote: "U. Cortez" said I believe a power surge toasted my power supply the other day, so I replaced it with a new 350W ATX PSU. After removing the burnt psu, I screwed the new psu into the case, hooked the ATX power supply to the motherboard, and hooked up power for various components (HD's, CD-ROM's). The motherboard's pilot light turns on to signify that it's getting power, but when I press the case's power button... nothing. No fans, no sound, no disk spinning, no signs of life at all (besides that pilot light being on). Am I forgetting something? I inspected all the components (and the motherboard and cpu) and none of them appear (or smell) to have been damaged. Where do I go from here? Any help would be appreciated. Motherboard: DFI AK70 (AMD 750 cpu). -U. PS, forgive the cross-post -- I don't have a news host and google is giving me errors when I try to post to some of these groups individually. If your MB has the 4-pin (square) auxiliary power connector, and you haven't connected it, you will get that result. Another possibility is that, while changing the PS, you accidentally disconnected the power button connector. It's small and easy to pull off its header. A mistake people make every now and then (including myself, and I've assembled lots of computers) is to set the FDD power connector one step to the side (only connecting three of the four pins), and this will cause a shortcut. Another possibility is that something else is dead too. All defects aren't visible to the naked eye... Disconnect all power cables except the one to the motherboard, and also disconnect the IDE and FDD cables (a defective drive can prevent a computer from starting). Then try to start the comp again. If it works now, start reconnecting components one by one, and do a test start between each... If it doesn't start even with all drives etc disconnected, your mobo might be fried. Or maybe your new PSU is defective too. Or something else... -- May all spammers die in horrible pains! Wanna e-mail me? Well, peter_e is correct, but the rest is obviously bogus... Try algonet in the .se TLD instead. On the back of the power supply, there is a switch where voltage can be set to either 120 volts or 240 volts. Make sure it is set to the correct voltage. This often overlooked. |
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