| Forum Home | ||||
| Press F1 | ||||
| Thread ID: 44669 | 2004-04-26 23:01:00 | Computer will only start in early morning! | Mzee (158) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 232278 | 2004-04-27 05:23:00 | Sounds to me like you have a dud capacitor. Try another PSU if you can, if that does not help it is the MB. |
ugh1 (4204) | ||
| 232279 | 2004-04-27 11:46:00 | Silly boy Graham. Computers don't have knees. Thats what secretaries are for. And legs. ;) | Winston001 (3612) | ||
| 232280 | 2004-04-27 12:14:00 | This is a very common problem in older computers, of which I have fixed quite a few. It is probably the PSU, if you open it and locate the Switching Fets or Xistors close to them around their heatsink you will find a pair of 1microFarad electrolytic capacitors connected as a multivibrator to start the switching circuit at startup by supplying some power to the regulator IC until the main circuit starts working correctly. They are nearly always 1uF 50V. Replace them both with the same high temperature type, normally black, and it goes without saying that this is a potentially dangerous operation which should only be done if you know what you are doing, you can get a nasty shock off the smoothing caps if the discharge resistors have gone open circuit as they often do. Hey presto you may be back in business with reliable operation. | zqwerty (97) | ||
| 232281 | 2004-04-29 04:45:00 | I have tried another power supply unit but no change. There is no voltage at the pins for the front ON switch so I guess that the motherboard is faulty. Pity, as when it works it is very stable with no problems. currently refusing to start at all. Is it possible to bypass the electronic switching in the ATX & replace it with a manual switch? I can't use an older power pack as the plugs are different. If I could get the power to flow, I am sure it will be OK. |
Mzee (158) | ||
| 232282 | 2004-04-29 04:58:00 | The lack of voltage at the switch would also signify a possible PSU fault, as that is where it is derived from. The motherboard does not supply the voltage, the PSU does. Is the PSU actually delivering the 5v for power_on when its not measured at the switch? Check that before blaming the motherboard. |
godfather (25) | ||
| 232283 | 2004-04-29 05:42:00 | It could be a MB fault ... there is a pullup resistor on the motherboard which feeds the front panel switch. Test the 5VSB connection of the main ATX connector. If that's OK, a resistor (4k7-10k) from that to the switch might make it all go again. ;-) You need the existing wires back to the switch, because they provide the logic levels to let the MB operate the PSU. |
Graham L (2) | ||
| 232284 | 2004-04-29 08:27:00 | Pin 9 (purple) 5vsb has 5volts on it, but the wires to the remote switch have nothing. The resisistor could be the answer. Pin14 (green) P_switch, if I connect the remote switch across 9 & 14 via a resistor, would that turn it on? I am not worried about system power control. Alternatively, I could attach the 'live' side of the remote switch to pin 9 via a resistor. and leave the other where it is on the mb. This gets more interesting all the time. I don't need the old computer, but I like things to work :-) |
Mzee (158) | ||
| 232285 | 2004-04-29 22:49:00 | Computer has refused to run for 2 days, this morning it fired up and is running well. I know that if I shut it down it will not start again for a long time. |
Mzee (158) | ||
| 232286 | 2004-04-29 23:03:00 | Gather friends and family around, they may want to say there last good buys. I know this sad time right now, but it is a perfect excuse to spend money and get a new one. Rob :( |
Rob99 (151) | ||
| 232287 | 2004-04-30 00:19:00 | To me the answer is obvious. Don't turn it off at night. Let it run 24/7. | JJJJJ (528) | ||
| 1 2 3 4 | |||||