Please help with dead system
in [Chips]
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From: nobody@nowhere.net on 15 Nov 2006 22:54 On Wed, 15 Nov 2006 18:45:56 -0500, Tony Hill <hilla_nospam_20(a)yahoo.com> wrote: >On Wed, 15 Nov 2006 20:48:53 GMT, Chris ><christo9(a)notalotofunwanted.aol.com> wrote: > >>I have a pc AMD 2000+ (home built) that will not power on. It powers >>on but no post, no beep codes just cpu fan, power supply fan and hard >>disk comes on. I believe it;s the CPU because when the problem >>happeed there was alot of dust across the top of the heat-sink >>completely covering the top restricting flow of air to the heat-sink. >>Since there are no beeps, no post, no video and the dirty heat sink, >>I'm guessing the cpu. Can anyone offer any advice? I don't want to >>waste money replacing the cpu and I have no known good cpu's or >>motherboards for this cpu. > >Standard process here is to try to isolate the issue. The problem >sounds like you have an electrical short somewhere in your system, >which means it could be ANY component. > >First, pull out ALL unnecessary components, ie any PCI cards, anything >connected to USB, keyboard, mouse, external speakers, hard drives, >floppy, etc. etc. Basically you want to be left with nothing other >than your motherboard, CPU and power supply. At the very least this >should give you some beep complaining about the lack of memory. > >If you get nothing at that point, then at least you've narrowed it >down to three parts, CPU, power supply and motherboard. Now, at this >point there are only two options. First is to physically inspect the >parts to see if there is an obvious proble. Most important here is to >check the capacitors on the motherboard to see if they are bulging, >leaking or just otherwise looking ugly. Given the approximate age of >your system, I would give it about a 75% or higher probability that >this is where you problem is. > >Now, if a visual inspection doesn't bring up anything obvious, the >second option is to swap parts. Of course, this requires compatible >replacement parts in order to test things, so hopefully you've got a >similar spare PC lying about and/or have a friend that does. Swap >parts out one at a time to try to isolate the issue, then replace the >defective part. >---------------------------- >Tony Hill >hilla <underscore> 20 <at> yahoo <dot> ca Smell the power supply. If it smells like something is burned, probably it is. NNN
From: Franc Zabkar on 16 Nov 2006 00:12 On 16 Nov 2006 00:36:03 GMT, Arno Wagner <me(a)privacy.net> put finger to keyboard and composed: >In comp.sys.ibm.pc.hardware.misc Chris <christo9(a)notalotofunwanted.aol.com> wrote: >> I have a pc AMD 2000+ (home built) that will not power on. It powers >> on but no post, no beep codes just cpu fan, power supply fan and hard >> disk comes on. I believe it;s the CPU because when the problem >> happeed there was alot of dust across the top of the heat-sink >> completely covering the top restricting flow of air to the heat-sink. >> Since there are no beeps, no post, no video and the dirty heat sink, >> I'm guessing the cpu. Can anyone offer any advice? I don't want to >> waste money replacing the cpu and I have no known good cpu's or >> motherboards for this cpu. > >If the HDD starts, then both +5V and +12V from the PSU is >reasonably good. HDDs have bad power detectors so they can >decide when to spin-up and spin-down. > >One way you could get your symptoms is if the reset line >(called power-good) from the PSU is failing. HDDs atsrt on >their own. The way to test for this is with a different >PSU. > >If the CPU is broken, you should get the according >beep code (or POST code, if your mainboard has a POST display). >However if it is partially broken, that may not work.... > >One thing you may try is removing the CPU and see whether you >get beep codes. If you do not, then the mainboard is likely >broken. If the CPU is not present or is not working, then you will not get any beep codes. - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Arno Wagner on 16 Nov 2006 10:02 In comp.sys.ibm.pc.hardware.misc Franc Zabkar <fzabkar(a)iinternode.on.net> wrote: > On 16 Nov 2006 00:36:03 GMT, Arno Wagner <me(a)privacy.net> put finger > to keyboard and composed: >>In comp.sys.ibm.pc.hardware.misc Chris <christo9(a)notalotofunwanted.aol.com> wrote: >>> I have a pc AMD 2000+ (home built) that will not power on. It powers >>> on but no post, no beep codes just cpu fan, power supply fan and hard >>> disk comes on. I believe it;s the CPU because when the problem >>> happeed there was alot of dust across the top of the heat-sink >>> completely covering the top restricting flow of air to the heat-sink. >>> Since there are no beeps, no post, no video and the dirty heat sink, >>> I'm guessing the cpu. Can anyone offer any advice? I don't want to >>> waste money replacing the cpu and I have no known good cpu's or >>> motherboards for this cpu. >> >>If the HDD starts, then both +5V and +12V from the PSU is >>reasonably good. HDDs have bad power detectors so they can >>decide when to spin-up and spin-down. >> >>One way you could get your symptoms is if the reset line >>(called power-good) from the PSU is failing. HDDs atsrt on >>their own. The way to test for this is with a different >>PSU. >> >>If the CPU is broken, you should get the according >>beep code (or POST code, if your mainboard has a POST display). >>However if it is partially broken, that may not work.... >> >>One thing you may try is removing the CPU and see whether you >>get beep codes. If you do not, then the mainboard is likely >>broken. > If the CPU is not present or is not working, then you will not get any > beep codes. That is wrong. The beep codes are produced by the keyboard MCU and that will beep a "CPU not present" if it is not contacted by the CPU after a certain time. Arno
From: Chris on 16 Nov 2006 19:35 On 16 Nov 2006 15:02:04 GMT, Arno Wagner <me(a)privacy.net> wrote: >In comp.sys.ibm.pc.hardware.misc Franc Zabkar <fzabkar(a)iinternode.on.net> wrote: >> On 16 Nov 2006 00:36:03 GMT, Arno Wagner <me(a)privacy.net> put finger >> to keyboard and composed: > >>>In comp.sys.ibm.pc.hardware.misc Chris <christo9(a)notalotofunwanted.aol.com> wrote: >>>> I have a pc AMD 2000+ (home built) that will not power on. It powers >>>> on but no post, no beep codes just cpu fan, power supply fan and hard >>>> disk comes on. I believe it;s the CPU because when the problem >>>> happeed there was alot of dust across the top of the heat-sink >>>> completely covering the top restricting flow of air to the heat-sink. >>>> Since there are no beeps, no post, no video and the dirty heat sink, >>>> I'm guessing the cpu. Can anyone offer any advice? I don't want to >>>> waste money replacing the cpu and I have no known good cpu's or >>>> motherboards for this cpu. >>> >>>If the HDD starts, then both +5V and +12V from the PSU is >>>reasonably good. HDDs have bad power detectors so they can >>>decide when to spin-up and spin-down. >>> >>>One way you could get your symptoms is if the reset line >>>(called power-good) from the PSU is failing. HDDs atsrt on >>>their own. The way to test for this is with a different >>>PSU. >>> >>>If the CPU is broken, you should get the according >>>beep code (or POST code, if your mainboard has a POST display). >>>However if it is partially broken, that may not work.... >>> >>>One thing you may try is removing the CPU and see whether you >>>get beep codes. If you do not, then the mainboard is likely >>>broken. > >> If the CPU is not present or is not working, then you will not get any >> beep codes. > >That is wrong. The beep codes are produced by the keyboard >MCU and that will beep a "CPU not present" if it is not >contacted by the CPU after a certain time. > >Arno Thanks for the replies so far... I have swapped the power supply for a known good supply, removed all cards, usb cables ram etc... Still no change. No beep codes and the CPU (heat sink) does not get warm at all. I gave it a good visual inspection under a magnifying glass (I am a pc technician) and there does not appear to be any problem with the motherboard. CPU's are still available for this system, but I'm not sure about MB's except maybe used... I have a post card but it's ISA and the MB doesn't have any ISA slots. I can try to boot the system with no cpu and see what happens. It's been very rare in my experience for a cpu to go bad, in over 10 years I've only seen one and it was a bad cache on a g3 chip, but at work I've always had known good equipment and with this I don't and I am not working at the moment. Any other ideas? Chris If life seems jolly rotten There's spmething you've forgotten and thats to laugh and smile and dance and sing!
From: Tony Hill on 16 Nov 2006 20:30
On Thu, 16 Nov 2006 16:12:43 +1100, Franc Zabkar <fzabkar(a)iinternode.on.net> wrote: >On Wed, 15 Nov 2006 18:45:56 -0500, Tony Hill ><hilla_nospam_20(a)yahoo.com> put finger to keyboard and composed: > >>On Wed, 15 Nov 2006 20:48:53 GMT, Chris >><christo9(a)notalotofunwanted.aol.com> wrote: >> >>>I have a pc AMD 2000+ (home built) that will not power on. It powers >>>on but no post, no beep codes just cpu fan, power supply fan and hard >>>disk comes on. I believe it;s the CPU because when the problem >>>happeed there was alot of dust across the top of the heat-sink >>>completely covering the top restricting flow of air to the heat-sink. >>>Since there are no beeps, no post, no video and the dirty heat sink, >>>I'm guessing the cpu. Can anyone offer any advice? I don't want to >>>waste money replacing the cpu and I have no known good cpu's or >>>motherboards for this cpu. >> >>Standard process here is to try to isolate the issue. The problem >>sounds like you have an electrical short somewhere in your system, > >A short would shut down the PSU. Clearly this is not happening in the >OP's case. In my experience a short will shut down the PSU only about 50% of the time at most. Other times it just hangs in a state exactly like the original poster described, no POST, no video, no beeps, but everything seems to be getting power fine. A short will only shut down the PSU if the voltage can be directly pulled from that power supply. If the short is on the far side of a voltage regulator which has a maximum current that it will supply, then your PSU never sees the short circuit and just happily goes about it's business. Another possibility is that the short circuit only lasted about a milisecond until it burned out some other chip and caused an open circuit. Same basic symptoms and same fix either way. ---------------------------- Tony Hill hilla <underscore> 20 <at> yahoo <dot> ca |