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#1
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Bad Motherboard?? ...short?
....have an older intel socket 478 motherboard in a 4 year old machine that I was working on today. The thing ran fine yesterday. Because this was an older spare machine, I wasn't as careful as I normally am. I drilled a hole (with a cordless drill) in the case to install another case fan. When I attempted to reboot, things weren't working correctly. As soon as the power supply is plugged in, the machine starts up even with the case power switch completely disconnected. It won't boot and won't even post. I get nothing on the video at all. If I pull the ram out, I get warning beeps that seem to mean that there is no ram. ...but that's it. I've pulled out and unplugged everything, but nothing helps. I've pulled out the bios battery to reset. Again, the case power switch doesn't work and instead the thing just comes on when the machine's power supply is switched on. I didn't have a spare power supply to swap in, but I can't see how the psu would matter. When unplugged the psu from the MB, the psu [properly] does not come on. As near as I can tell, running the drill into the front of the case must have caused something to short in the board. okay, I know this was stupid, and I would not have done this on a new machine. Is there any other explanation other than a bad MB? -- Posted via a free Usenet account from http://www.teranews.com |
#2
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Bad Motherboard?? ...short?
"""running the drill into the front of the case .."""
It looks like must be this drilling...perhaps you damaged the front panel Power Switch / Reset button / Led / USB wires n sockets / Audio ..... whatever is on the front... try disconnecting the front panel wires ....unplug all of them .. The only one you have to have is the power On/Off ..operate that (now) disconnected line by shorting the contacts as needed on the M.Board. I suppose you MIGHT have damaged a Hard Drive / Floppy / CD so as to stop the start up... My bet goes on the Power or reset switch damaged open / or shorted. OR some scrap o metel got into the M.Board...turn it upside down & kick it ??? (a little bit). Mouse @@@ |
#3
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Bad Motherboard?? ...short?
"Trimble Bracegirdle" wrote in message ... """running the drill into the front of the case ..""" It looks like must be this drilling...perhaps you damaged the front panel Power Switch / Reset button / Led / USB wires n sockets / Audio ..... whatever is on the front... try disconnecting the front panel wires ...unplug all of them .. The only one you have to have is the power On/Off ..operate that (now) disconnected line by shorting the contacts as needed on the M.Board. I suppose you MIGHT have damaged a Hard Drive / Floppy / CD so as to stop the start up... My bet goes on the Power or reset switch damaged open / or shorted. OR some scrap o metel got into the M.Board...turn it upside down & kick it Thanks. I should have specified that I ran the drill into a thin bare strip of metal that was no where near the actual power switch. ...and I've pretty much tried everything that you mentioned - although there is no sense in having to short the contacts, because as I mentioned, the power turns on immediately even with the front panel wires all completely unplugged. I actually removed the entire MB and blew the case and MB out with air. ....still the same. I can get a spare power supply to the thing tomorrow, but I don't really see that this will do any good as the power supply does shut off when it is disconnected from the MB. I also disconnect all floppy/CD/ and hard drives. The thing should post without the drives even if it goes no further. -- Posted via a free Usenet account from http://www.teranews.com |
#4
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Bad Motherboard?? ...short?
Jeff wrote:
...have an older intel socket 478 motherboard in a 4 year old machine that I was working on today. The thing ran fine yesterday. Because this was an older spare machine, I wasn't as careful as I normally am. I drilled a hole (with a cordless drill) in the case to install another case fan. When I attempted to reboot, things weren't working correctly. As soon as the power supply is plugged in, the machine starts up even with the case power switch completely disconnected. It won't boot and won't even post. I get nothing on the video at all. If I pull the ram out, I get warning beeps that seem to mean that there is no ram. ...but that's it. I've pulled out and unplugged everything, but nothing helps. I've pulled out the bios battery to reset. Again, the case power switch doesn't work and instead the thing just comes on when the machine's power supply is switched on. I didn't have a spare power supply to swap in, but I can't see how the psu would matter. When unplugged the psu from the MB, the psu [properly] does not come on. As near as I can tell, running the drill into the front of the case must have caused something to short in the board. okay, I know this was stupid, and I would not have done this on a new machine. Is there any other explanation other than a bad MB? When you drill a metal case, you remove all hardware, and keep a vacuum cleaner handy. That way, you can collect all the bits of conducting metal that the drilling operation will create. If those fall onto the motherboard, there is no way to predict what will happen. Disassemble the thing, clean up inside, and reassemble it. Maybe you'll get lucky, or something. Paul |
#5
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Bad Motherboard?? ...short?
"Paul" wrote in message ... Disassemble the thing, clean up inside, and reassemble it. Maybe you'll get lucky, or something. Paul Thanks. ...but I already tried this. I think that I have learned my lesson. ....good I didn't do something like this on a new, expensive machine. I'll try a new power supply tomorrow, but I don't expect much. At least a used board from ebay is only about $40. -- Posted via a free Usenet account from http://www.teranews.com |
#6
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Bad Motherboard?? ...short?
On Mar 3, 9:33 pm, "Jeff" wrote:
"Paul" wrote in ... Disassemble the thing, clean up inside, and reassemble it. Maybe you'll get lucky, or something. Thanks. ...but I already tried this. I think that I have learned my lesson. ... I'll try a newpower supplytomorrow, but I don't expect much. At least a used board from ebay is only about $40. Why would you now replace a power supply? For example, all ATX power supplies must have all outputs shorted together and never be damaged. If a metal chip caused a short, then protection circuits standard inside power supplies must protect everything without damage. What were the beep codes? That idenifies some items as working. And if you got beep codes, the power supply is working - at least as best you can tell until those voltages are measured with a 3.5 digit multimter. A spare power supply is wasted time and money. If swapping things to fix it, then you may have exponentially complicated the problem. Start by establishing what is working. The 3.5 digit meter and this procedure is a good start - without anythng removed or disconnected from the machine: "When your computer dies without warning....." starting 6 Feb 2007 in the newsgroup alt.windows-xp at: http://tinyurl.com/yvf9vh Is BIOS battery defective? Again, don't even remove the battery. In but seconds, meter could have measured battery and determined if battery was connected. Removing and reseating BIOS battery could have adversely changed some CMOS settings - just another example of exponentially complicating a problem. Testing a power supply disconnected from a load and without numbers from that meter says little. Even some defective supplies will come on during that test. You are doing tests that only say maybe. You need diagnostic procedures that say definitely good or definitely bad. Shotgunning can even make things worse. Did a metal fragement short something? Well once that short is removed, then board will work again. ICs work just fine after a short circuit is removed - an IC design standard dating back to late 1960 designs. If a metal fragment caused the problem and board still does not work; then metal fragment is still on the board. You have apparently assumed a metal fragment causes damage in direct contradiction to how digital ICs work. But then your every test still does not even say the power supply is OK. Your each test has only said maybe this might be working OK. You need tests that say "yes it is OK without a doubt so I will move on to other suspects". Get the meter. Stop guessing. |
#7
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Bad Motherboard?? ...short?
"w_tom" wrote in message s.com... A spare power supply is wasted time and money. If swapping things to fix it, then you may have exponentially complicated the problem. Start by establishing what is working. The 3.5 digit meter and this procedure is a good start - without anythng removed or disconnected from the machine: Thanks w_tom. ...wasn't going to buy a psu, I had a spare that I was going to plug in. ....didn't even need to remove anything from the case. I would agree with you that buying one would be a waste of time and money. .... at this point with most everything removed, I can simply plug in the spare psu quicker than I can test the old one. Is BIOS battery defective? Again, don't even remove the battery. In but seconds, meter could have measured battery and determined if battery was connected. Removing and reseating BIOS battery could have adversely changed some CMOS settings - just another example of exponentially complicating a problem. okay, I already have a meter, but didn't have one where I was working on the machine. I'll probably go back today and take the meter with me. The bios settings were all default, other than the boot drive options, so I wasn't really worried about them. But then your every test still does not even say the power supply is OK. Your each test has only said maybe this might be working OK. You need tests that say "yes it is OK without a doubt so I will move on to other suspects". Get the meter. Stop guessing. I agree with most of what you suggest. Here is what I don't know 100%, but I think I have it correct - perhaps someone can confirm or correct me. 1) When idle, the PSU supplies a minimal voltage to the MB that simply allows the case power button to work. 2) When the case power button is pushed, a circuit is completed in the MB, 3) The completed circuit sends a signal to the PSU and the PSU starts fully. 4) The PSU fan comes on at this point. The PSU sends a signal to the MB that it is now on. 5) The bios then starts and attempts its POST. 6) The POST starts and will provide beep codes if something prevents it from continuing to the point that you can get video output. What is happening in my case is that the first 3 steps above are being circumvented. As soon as 110 voltage is provided to the PSU, the entire machine goes on without touching the case power switch and this occurs even if the case power switch leads are removed from the MB. ...but if the PSU is disconnected from the MB, then the PSU does not start - i.e., the fan does not come on. I assume that whatever occurs in step 2 above, where something tells the PSU to turn on completely, is the problem. I assume that this occurs due to something within the MB itself and not within the processor or elsewhere. As far as I know, if I would completely remove the processor, I should still get to about step 4 in the normal way before halting. I assume that the behavior causing steps 1, 2, and 3 to be skipped can only be due to a bad MB and that this does not have anything to do with the bios (so the bios battery can't be the problem?) and that it can't be due to something within the PSU, since the PSU does properly stay off when disconnected from the MB. I also assume that it can't be due to the case power switch because it still occurs when the case power switch is disconnected. I would normally just scrap the thing as it is a bit old. ...but what is going on is that this was my old primary machine that I just upgraded and I was going to keep using it as a file server. So, I just spent two days setting up an inexpensive raid 1 array in it, loading W2K3, doing all patches, configuring it just the way I wanted, etc.. I don't want to repeat all of that work (okay, mostly sitting around waiting for things to install, but I can't walk away for long periods), and I can't just move the raid array to a new machine. So replacing the MB might be the most time efficient, since I should then be able to just keep the raid array as it is. I would like like to narrow things down so that I know that it must be the MB and nothing else before I spend the time and money getting a new one. I'm not 100% positive, for example, that a bad bios battery can't in some way cause this type of thing. -- Posted via a free Usenet account from http://www.teranews.com |
#8
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Bad Motherboard?? ...short?
"Jeff" wrote in message .. . Okay, One more/final update - the meter showed that the bios battery was okay at 3 volts. Plugging in another power supply didn't do anything. The board still starts immediately instead of waiting for the case power supply button to be pushed. If I completely pull out the processor, the board does not start (e.g., the case fans don't go on), but if I put the processor back in, once again everything starts up as soon as the 110 power is turned on. I would assume that the MB is designed so that a processor is required for anything to start so the above doesn't indicate anything about whether or not the processor is okay. ...I've never experimented on any other machine, however. The only real remaining question is whether there is any remote possibility that the problem could be in the processor instead of the MB. I'm about 99% certain that it's the MB alone, but could someone confirm this before I attempt to buy another board that I'll likely not be able to return. Jeff -- Posted via a free Usenet account from http://www.teranews.com |
#9
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Bad Motherboard?? ...short?
On Sat, 3 Mar 2007 16:54:21 -0600, "Jeff" wrote:
...have an older intel socket 478 motherboard in a 4 year old machine that I was working on today. The thing ran fine yesterday. Because this was an older spare machine, I wasn't as careful as I normally am. I drilled a hole (with a cordless drill) in the case to install another case fan. When I attempted to reboot, things weren't working correctly. As soon as the power supply is plugged in, the machine starts up even with the case power switch completely disconnected. It won't boot and won't even post. I get nothing on the video at all. If I pull the ram out, I get warning beeps that seem to mean that there is no ram. ...but that's it. I've pulled out and unplugged everything, but nothing helps. I've pulled out the bios battery to reset. Again, the case power switch doesn't work and instead the thing just comes on when the machine's power supply is switched on. I didn't have a spare power supply to swap in, but I can't see how the psu would matter. When unplugged the psu from the MB, the psu [properly] does not come on. As near as I can tell, running the drill into the front of the case must have caused something to short in the board. okay, I know this was stupid, and I would not have done this on a new machine. Is there any other explanation other than a bad MB? Try taking it out of the case and running it. I was given a system which was supposedly dead but it ran with no problem when I removed all the parts and connected the PSU out of the box. I assume there was a short against the metal casing. Putting it all back together in another case solved it. km |
#10
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Bad Motherboard?? ...short?
On Mar 4, 10:06 am, "Jeff" wrote:
... 1) When idle, the PSU supplies a minimal voltage to the MB that simply allows the case power button to work. 2) When the case power button is pushed, a circuit is completed in the MB, 3) The completed circuit sends a signal to the PSU and the PSU starts fully. 4) The PSU fan comes on at this point. The PSU sends a signal to the MB that it is now on. 5) The bios then starts and attempts its POST. 6) The POST starts and will provide beep codes if something prevents it from continuing to the point that you can get video output. What is happening in my case is that the first 3 steps above are being circumvented. As soon as 110 voltage is provided to the PSU, the entire machine goes on without touching the case power switch and this occurs even if the case power switch leads are removed from the MB. ...but if the PSU is disconnected from the MB, then the PSU does not start - i.e., the fan does not come on. I assume that whatever occurs in step 2 above, where something tells the PSU to turn on completely, is the problem. I assume that this occurs due to something within the MB itself and not within the processor or elsewhere. As far as I know, if I would completely remove the processor, I should still get to about step 4 in the normal way before halting. I assume that the behavior causing steps 1, 2, and 3 to be skipped can only be due to a bad MB and that this does not have anything to do with the bios (so the bios battery can't be the problem?) and that it can't be due to something within the PSU, since the PSU does properly stay off when disconnected from the MB. I also assume that it can't be due to the case power switch because it still occurs when the case power switch is disconnected. ... The purple wire provides power to the power supply controller. Green wire tells power supply to turn on. Power supply has but two seconds to determine all voltages are OK; then tell controller via gray wire. This and more is summarized in "PC doesn't start" on 15 Feb 2007 in microsoft.public.windowsxp.hardware at: http://tinyurl.com/25fvc7 If any one voltage does not try to start, then that would be the suspect circuit. In your case (because that other supply is probably good), then the voltage that does not try to turn on is where you look for the problem on motherboard or peripherals. Of course, because computer is powered even when powered off (see voltage on purple wire), always remove power cord from AC wall receptacle before connecting or disconnecting anything. Pulling out processor will not discover anything useful. Processor even with its own power supply rarely fail. Since the beep codes exist, then processor and some other (limited) motherboard functions are working. If power supply only powers with some things removed, well that is useful information even is computer does not boot. Also important are those power supply voltage numbers and responses. They can provide additional information that you don't realize. Numbers that make others useful help. |
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