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| Thread ID: 138020 | 2014-09-24 22:17:00 | Power supply problem? | coldot (6847) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 1384688 | 2014-09-24 22:17:00 | Desktop PC was reluctant to start each time when switched on at wall socket - often had to try three or four times on/off, count to 10, on/off..... For the past week I have left the wall socket on and simply press the start button. Now it starts immediately every time. What is actually powered up in the power supply when the desktop is not on? Is it using much power in that state? |
coldot (6847) | ||
| 1384689 | 2014-09-24 23:19:00 | Re whats being used, have a read: en.wikipedia.org(computer) As for how much power it will actually consume, its would be very hard to measure, not enough to worry about. BUT what the PSU is telling you is that its starting to go faulty. Replace it before it does any real damage. Generally when a PSU fails one of two things happen. It either does the decent thing and simply dies, OR in some cases stops acting as a transformer because that is basically what it is, reduces 230/240V down to 3.3, 5 & 12 Volt that computers actually run on, and for a split second puts a full 240 volt into 3.3, 5 & 12 volt components. You don't need to be good at maths to work out that means frying components. (seen it happen countless times) |
wainuitech (129) | ||
| 1384690 | 2014-09-24 23:54:00 | Given that it works when left on maybe rather than all those attempts what you needed was to turn it on and wait a while. There is some standby voltage supplied to the motherboard even when off but it's an insignificant amount of power. I agree with Wainui though, not good symptoms for a PSU to be having. It's possible it's only the start up circuit that's playing up but why take the risk, if the PSU dies it could take the whole PC with it. On the other hand though it could actually be a motherboard fault as the signal to start comes via the motherboard and can sometimes fail to work if there is a fault. To prove it is a little risky if you are not comfortable poking wires into power supply connectors. You may want to ask a local tech to take a look at it and prove whether it's the PSU or the motherboard. A simple swap out is the easiest way if a spare PSU is available. If you want to try yourself and don't have a spare PSU try this at your own risk... If you short the green wire on pin 16 of the 24 way motherboard connector to one of the black wires near it the power supply should start up - this bypasses the motherboard signal and forces the PSU on. If that works every time and the normal way doesn't it could be a motherboard fault, if it behaves the same it's probably the PSU. You can do this with a small piece of wire or a bent paper clip while the connector is still attached or if you are unwilling to risk that you can disconnect it and do it from the other side. Some components will still work when they are starting to wear out as long as the power is on but will do what you describe when powered off. Capacitors for example can dry out and start to behave oddly before finally failing. |
dugimodo (138) | ||
| 1384691 | 2014-09-25 08:28:00 | Thanks for your advice. Progress report. Swapped power supply but now I remember that the slow start was usually only when cold, so I'll make sure it's completely off overnight and report back on the morning awakening. |
coldot (6847) | ||
| 1384692 | 2014-09-25 08:39:00 | MOBO battery getting weak? And BIOS losing config? | Paul.Cov (425) | ||
| 1384693 | 2014-09-25 08:51:00 | Sometimes its a process of elimination to find the fault. Heat related like this are a real pain. Had a couple that would not start cold, then once it did, you had to wait for hours or the following day to find out if the fix was the right one. :( | wainuitech (129) | ||
| 1384694 | 2014-09-25 20:29:00 | Unlikely to be BIOS battery. They are so inexpensive that I replace them at the first sign of problems. Started immediately this morning. It's a good beginning but I'll keep observing for a week before I claim that replacement power supply has solved the problem. |
coldot (6847) | ||
| 1384695 | 2014-09-25 21:09:00 | Having done that, I hope it was the problem. I too once had a similar problem and it turned out to be a faulty power switch at the wall. | Bryan (147) | ||
| 1384696 | 2014-09-26 20:43:00 | Once again it started immediately this morning. It looks like success - thank you. | coldot (6847) | ||
| 1384697 | 2014-09-26 23:19:00 | Generally when a PSU fails one of two things happen. It either does the decent thing and simply dies, OR in some cases stops acting as a transformer because that is basically what it is, reduces 230/240V down to 3.3, 5 & 12 Volt that computers actually run on, and for a split second puts a full 240 volt into 3.3, 5 & 12 volt components. It would require a catastrophic failure of the PSU including a huge light and sound show for you to ever see 240v on the output of a PC PSU, and would usually require some 'help' eg: pouring water all over it. What usually happens is the capacitors fail, the PSU's regulation circuitry can't cope, and it ends up outputting a higher voltage than it should. You don't need 240v to blow a motherboard. 10v on the 5vSB rail for example is good enough to wreck just about any motherboard. |
Agent_24 (57) | ||
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