Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
A while back I bought a used 500mhz computer on Ebay. (that was my
big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber |
#2
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
In article , plumber1
@________.com says... A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber Those are probably inductors used to limit noise on the DC power lines. If they overheated, that usually indicates a fault on the motherboard. It takes a great deal of energy to burn those lines, so I would look for a damaged regulator or shorted capacitor on the board. The problem may be a short on one of the inside layers of the board as well, so you may have to remove the board and try to look through it. If one of the layers is a ground plane, you will not be able to see through the board. - Tim - |
#3
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
"Tim" wrote in message ... In article , plumber1 @________.com says... A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber Those are probably inductors used to limit noise on the DC power lines. If they overheated, that usually indicates a fault on the motherboard. It takes a great deal of energy to burn those lines, so I would look for a damaged regulator or shorted capacitor on the board. The problem may be a short on one of the inside layers of the board as well, so you may have to remove the board and try to look through it. If one of the layers is a ground plane, you will not be able to see through the board. - Tim - Actually the most of the inductors described are not noise filters at all, but part of a switching power supply regulator that converts either 5 or 3.3 volt supplies to lower voltages such as 1.5 volts for the CPU. They often operate at high currents (perhaps as much as 10 - 20 amperes). There are also some boards that have regulators to generate higher voltages for other components on the board such as built in audio or RS232 ports. I have never seen one get hot enough to cause smoke without also something else wrong. My guess is that particular regulator was associated with something other than the main CPU/memory system or else the machine would not run. Do all of the I/O ports, built in peripherals, and add-on cards operate? David |
#4
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
"David" wrote in message t... "Tim" wrote in message ... In article , plumber1 @________.com says... A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber Those are probably inductors used to limit noise on the DC power lines. If they overheated, that usually indicates a fault on the motherboard. It takes a great deal of energy to burn those lines, so I would look for a damaged regulator or shorted capacitor on the board. The problem may be a short on one of the inside layers of the board as well, so you may have to remove the board and try to look through it. If one of the layers is a ground plane, you will not be able to see through the board. - Tim - Actually the most of the inductors described are not noise filters at all, but part of a switching power supply regulator that converts either 5 or 3.3 volt supplies to lower voltages such as 1.5 volts for the CPU. They often operate at high currents (perhaps as much as 10 - 20 amperes). There are also some boards that have regulators to generate higher voltages for other components on the board such as built in audio or RS232 ports. I have never seen one get hot enough to cause smoke without also something else wrong. My guess is that particular regulator was associated with something other than the main CPU/memory system or else the machine would not run. Do all of the I/O ports, built in peripherals, and add-on cards operate? David New motherboards with CPUs and often CPU fans can be had at retailers such as Frys (they also have a a web) for $80 to $100. I have built many PCs with these: P4s, AMD etc, |
#5
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
wrote in message ... A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber Something has shorted on the motherboard, it's not worth trying to repair one so old, but the rest of the components will be fine. |
#6
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
wrote in message ... A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber Look for the buldging electrolytic capacitors....Paul |
#7
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
I have seen old Pentiums run at the wrong core voltage, and they would
work, maybe hotter or less stable. It could be a shorted regulator putting out 3.3V to the 1,5V line, not sure if a P III would hold that but it might work for some time. David wrote: Actually the most of the inductors described are not noise filters at all, but part of a switching power supply regulator that converts either 5 or 3.3 volt supplies to lower voltages such as 1.5 volts for the CPU. They often operate at high currents (perhaps as much as 10 - 20 amperes). There are also some boards that have regulators to generate higher voltages for other components on the board such as built in audio or RS232 ports. I have never seen one get hot enough to cause smoke without also something else wrong. My guess is that particular regulator was associated with something other than the main CPU/memory system or else the machine would not run. Do all of the I/O ports, built in peripherals, and add-on cards operate? David |
#9
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
This may be educational
http://www.badcaps.net/ Personally, I would not have spent a dime for a 500 MHz PC, when Fry's area selling brand new Pentium 4 with software for $ 299 (last year models being replaced by new ones). gb wrote in message ... A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber |
#10
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
Hi!
It could be a shorted regulator putting out 3.3V to the 1,5V line, not sure if a P III would hold that but it might work for some time. If the coil got hot enough to smoke, the voltage may have been held down to a much lower value by virtue of the coil's resistance. William |
#11
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
|
#12
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
Thanks for the link. You (and others) were correct. There are 3 caps
right next to this coil and very close to some major power transistors (probably regulators). All 3 of those caps have bulged tops and there seems to be a brown stain next to one of them. Until looking at the pics on this website, I did not know what to look for. It's now obvious those 3 caps are fried. Oddly enough that motherboard still boots and runs. In fact I loaded windows and a bunch of hi-res photos and no problems. I think I am going to see if I can find three 1000uf caps and replace them. No sense trashing a working motherbd for $5 worth of caps. I wont replace the others, jsut those three. That coil is charred but it still works. Since the windings dont touch I dont see where it matters if the enamel is burned off. I got a soldering iron so what the heck. Maybe I'll turn that into my Windows 98 machine. I still like using 98 when XP ****es me off, which it does quite often. Just curious. What exactly do those coils do? Every motherbd has them, at least 2 of them. They are just a core with about 10 windings. All I can figure is a choke of some sort. ---------------------- On Tue, 15 May 2007 05:44:57 -0500, "w9gb" wrote: This may be educational http://www.badcaps.net/ Personally, I would not have spent a dime for a 500 MHz PC, when Fry's area selling brand new Pentium 4 with software for $ 299 (last year models being replaced by new ones). gb wrote in message .. . A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber |
#13
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
wrote in message ... Thanks for the link. You (and others) were correct. There are 3 caps right next to this coil and very close to some major power transistors (probably regulators). All 3 of those caps have bulged tops and there seems to be a brown stain next to one of them. Until looking at the pics on this website, I did not know what to look for. It's now obvious those 3 caps are fried. Oddly enough that motherboard still boots and runs. In fact I loaded windows and a bunch of hi-res photos and no problems. I think I am going to see if I can find three 1000uf caps and replace them. No sense trashing a working motherbd for $5 worth of caps. I wont replace the others, jsut those three. That coil is charred but it still works. Since the windings dont touch I dont see where it matters if the enamel is burned off. I got a soldering iron so what the heck. Maybe I'll turn that into my Windows 98 machine. I still like using 98 when XP ****es me off, which it does quite often. Just curious. What exactly do those coils do? Every motherbd has them, at least 2 of them. They are just a core with about 10 windings. All I can figure is a choke of some sort. The coils are an important part of a switching voltage regulator.... as are the capacitors. The caps are probably low ESR type. -- Ed ---------------------- On Tue, 15 May 2007 05:44:57 -0500, "w9gb" wrote: This may be educational http://www.badcaps.net/ Personally, I would not have spent a dime for a 500 MHz PC, when Fry's area selling brand new Pentium 4 with software for $ 299 (last year models being replaced by new ones). gb wrote in message . .. A while back I bought a used 500mhz computer on Ebay. (that was my big mistake). When I got it, it worked well, except for the floppy drive. I contacted the seller immediately and he sent me another floppy drive to replace the bad one. I replaced the drive and turned it on. It worked fine but since I wanted to add another harddrive (as soon as I got one), I left the cover off the case. That turned out to be a good thing, because I was sitting at my desk on the web when I noticed a hot burnt odor. Then I saw smoke. I looked at the computer and saw smoke coming off the motherboard. There are these donut looking things on the board. They look like a white lifesaver candy wound with 20 or 30 loops of a fairly thick enamelled wire (actually not all that thick, probably a 20 gauge). Oddly enough, the computer continued to work the whole time, and I know that because I saved whatever I was typing before I shut off the power. I found all the enamel burned off the wire on that coil and it was black. I was glad the cover was off the case so I could see what was happening. I carefully looked for anything that might create a short and found nothing. I got my fire estinguisher (just in case), and turned the computer back on. It booted up, and worked fine. I turned it on and off several more times, and it still worked, and I never saw more smoke. The seller would not replace it because it was 2 ot 3 weeks later by then. What could have caused this? What are those coild called and what is their purpose. It seems there are 2 or 3 of them on all motherboards. Needless to say, I do not use this computer. I dont trust it. I just took out all the drives, ram, and cards and put them on another motherboard. I know I can use that case again, but question the power supply. I definately will not use the motherboard again, and worry about the CPU. Anyone have any idea what caused this? I'm just curious more than anything else. I figure the MB is best going into the trash, and I have a faster CPU now too. Thanks Plumber |
#14
Posted to sci.electronics.repair
|
|||
|
|||
What happened to this motherboard?
|
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
What ever happened to | Home Repair | |||
What Happened?????? | Woodturning | |||
What happened to it? | Metalworking | |||
Wonder how *that* happened... | Metalworking | |||
anybody know what happened to | Woodworking |