| T O P I C R E V I E W |
| pebe |
Posted - Jan 03 2011 : 11:49:21 AM
Every few days I have a problem starting my computer. Pressing the 'on' button does nothing. Shorting out the start button proves that it is not faulty.
I have found that if I switch off the mains supply, then switch it on again at the same time that I press the button, I get lucky after several attempts and it will start. It behaves itself for another few days then the fault reappears.
The same button also provides for switching off, so I assume the power up is some form of toggle circuit. ButI don't know whether it is in the power supply or on the main board.
Any ideas? All suggestions welcomed.
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| 8 L A T E S T R E P L I E S (Newest First) |
| wasssup1990 |
Posted - Jan 18 2011 : 8:39:54 PM
The PB is unable to turn the PS off via the D-Flip flop. I think he's leaving out other parts of the circuit for simplicity. To turn the PS off a high must be on D and then clocked in. There would have to be another wire going from the button to another chip (possibly the BIOS) to signal an interrupt so that the OS can begin its shutdown sequence. Forceful shutdown by holding the PB for a few seconds is probably handled by the BIOS and it just clocks a high into the D-FF after those few seconds has elapsed. |
| pebe |
Posted - Jan 18 2011 : 07:04:59 AM
I watched the long blurb about the D-type and wondered how, as drawn, the same push button could turn the PS off as well as on. As the explanation was about to be given and the mystery unravelled(?) at 5.42 minutes, the display stopped. I tried a second time and the same thing happened.
Just how does the PB stop the power? |
| wasssup1990 |
Posted - Jan 18 2011 : 03:10:57 AM
http://www.youtube.com/user/wa2kwl#p/u/12/IVFY98ozefw |
| sergiosparks |
Posted - Jan 17 2011 : 11:44:31 PM
Hi Pebe..the other day i had similar syptom like that of your sustem.Took out the peripherals one by one hoping to 'get the problem gadget.Cleaned the whole motherboard for dust..Took out the power supply
and 'jumped the green to to black,it turned on the internal fan which would suggest that it is OK..I opened the power supply for dusting and visual inspection since its out anyway..I saw a bloated top capacitor,1000 uf ,10v at the 5V supply..replacing it restored my system..and I thought it was the motherboard..
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| wasssup1990 |
Posted - Jan 04 2011 : 09:53:22 AM
Although this has never happened to me before but perhaps one of your devices other than the motherboard is failing and causing the power supply to shutdown. Fans seizing? Hard Drive dieing? Graphics card fault? Bad connections? I don't have your machine here so it's hard to tell exactly the cause.
Sometimes a good whack can solve a problem like knocking some connections clean of oxidation. Who knows? |
| wasssup1990 |
Posted - Jan 04 2011 : 05:34:55 AM
What I was saying is that I have had occurrences where both a motherboard fault or a power supply fault prevented the computer from starting properly. |
| pebe |
Posted - Jan 04 2011 : 04:26:05 AM
Did you find out which of the two it was? |
| wasssup1990 |
Posted - Jan 04 2011 : 02:11:35 AM
It seems you have isolated the problem to either your motherboard or power supply. Try to power your computer with a power supply that you know works and then you'll be able to tell where the problem is. I have had issues similar to this before and the PSU or motherboard were the only parts at fault. |
