Please help with dead system
in [Chips]
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From: Arno Wagner on 16 Nov 2006 21:26 In comp.sys.ibm.pc.hardware.misc Chris <christo9(a)notalotofunwanted.aol.com> wrote: > 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, I agree to that. Basically only the very visible "chip is burnt" type, when the heatsink falls off an older CPU. > 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? Well, the total no-reaction would lead me to believe that the chipset is shot. With no CPU you should get a beep-code. If not, the board is broken. Arno
From: Franc Zabkar on 17 Nov 2006 00:23 On Thu, 16 Nov 2006 20:30:54 -0500, Tony Hill <hilla_nospam_20(a)yahoo.com> put finger to keyboard and composed: >On Thu, 16 Nov 2006 16:12:43 +1100, 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: >>>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 depends entirely on the system and how the CPU failed. Some >systems will beep if they do not detect a CPU, others will not. Of >those that will beep if a CPU is not detected, they *might* beep if >the CPU has failed or they might not. Beep codes are (usually) >handled entirely by the motherboard with no CPU intervention. >---------------------------- >Tony Hill >hilla <underscore> 20 <at> yahoo <dot> ca Just to be clear, you don't mean *all* the POST beep codes, do you? - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Trent on 17 Nov 2006 05:20 On 16 Nov 2006 15:02:04 GMT Arno Wagner <me(a)privacy.net> wrote in Message id: <4s3crcFthuckU1(a)mid.individual.net>: >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. Proof please. The beep codes are generated from the 8254 timer chip, which must be programmed by the processor. If the processor is missing or cannot do code/data fetches from the BIOS ROM, there are *no* post codes. Period.
From: The little lost angel on 17 Nov 2006 11:25 On Fri, 17 Nov 2006 05:20:07 -0500, Trent <none(a)dev.nul.pissoff> wrote: >On 16 Nov 2006 15:02:04 GMT Arno Wagner <me(a)privacy.net> wrote in Message >id: <4s3crcFthuckU1(a)mid.individual.net>: > >>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. > >Proof please. The beep codes are generated from the 8254 timer chip, which >must be programmed by the processor. If the processor is missing or cannot >do code/data fetches from the BIOS ROM, there are *no* post codes. Period. I had seen modern motherboards which are able to tell if the CPU is not working. Specifically on an older AOpen K7 board, I had the occasion where the board was able to tell me "Your CPU may have a problem" using the beeper as a voice speaker. My older MSI Socket A board also had a diagnostic LED that had codes for a improperly installed or non-functional CPU, basically equates to a dead CPU. My current one probably has beep codes for that as well but I'm too lazy to dig up the manual :ppPp -- A Lost Angel, fallen from heaven Lost in dreams, Lost in aspirations, Lost to the world, Lost to myself
From: Arno Wagner on 17 Nov 2006 18:54
In comp.sys.ibm.pc.hardware.misc Trent <none(a)dev.nul.pissoff> wrote: > On 16 Nov 2006 15:02:04 GMT Arno Wagner <me(a)privacy.net> wrote in Message > id: <4s3crcFthuckU1(a)mid.individual.net>: >>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. > Proof please. The beep codes are generated from the 8254 timer chip, which > must be programmed by the processor. If the processor is missing or cannot > do code/data fetches from the BIOS ROM, there are *no* post codes. Period. Since your information is wrong, I don't feel I have to proof anything. But please remain unenlightened, if you want. Otherwise have a look at the schematics again. Should be at least PC-AT, since I think the original PC and XT actually could not do this AFAIK. Arno |