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Thread ID: 33355	2003-05-14 08:58:00	Power Supply wake-up	James Kirk (3742)	Press F1

Post ID	Timestamp	Content	User
144028	2003-05-14 08:58:00	My computer often won't start up when the button is pushed . The heartbeat LED is flashing so power is ready . Sometimes it just comes right . Other times it is necessary to turn the power off at the wall . If these don't succeed, then unplugging and reconnecting the 20-pin ATX connector to the motherboard always works . There is a pin (14) in the ATX connector marked "PS_ON"; it is opposite a pin (4) marked +5VDC . The button on the front puts a momentary short across 2 pins marked "PS-ON" on the mainboard (ATC-6220 Intel 440BX AGP); the processor is 300MHz P2 . These pins have 5VDC across them when the power supply is otherwise not working . I have been assuming that the mainboard issues a start instruction via the 20-pin ATX connector . Can anyone advise me how this sytem for starting the power supply is supposed to work, and whether my problem is likely to be with the mainboard or the power supply, and how this can be tested? Also, should shorting pins 4 and 14 start the power, or will I short a power rail?	James Kirk (3742)
144029	2003-05-14 10:38:00	At the risk of being insulting is the pc actually off or on standby? a lot of pc's are set to flash the power light when on standby.	tweak'e (174)
144030	2003-05-14 10:47:00	Hmmm .... I was thinking the same tweak'e All my PC's (5 all up) only display a "heartbeat" if in standby/sleep/hibernate. Never when "off"	godfather (25)
144031	2003-05-14 10:50:00	I'm not sure how to define "standby". The AC power is on, and the 5VDC is on, but not 3.3VDC or 12VDC. For years, pushing the button on the front of the tower has woken up the power supply which is noted by the fan starting, and the HDD chirping. Do you think that there is a software switch that might have altered and needs changing back? As the problem is intermittent I doubt that it is an altered setting, but I don't know where to look. Does the power startup work as I surmised in my origianl message?	James Kirk (3742)
144032	2003-05-14 10:53:00	This system has always had the flashing LED, which steadies when the power supply wakes up, and starts flashing (pulsing) again when the system is shutdown from the desktop.	James Kirk (3742)
144033	2003-05-14 10:56:00	how do you turn the pc off? do you select shutdown or standby? you have a rough idea on how the pc gets turned on. i can't remember the exact pins.	tweak'e (174)
144034	2003-05-14 11:02:00	Don't know if it is the same, but I had a similar problem which a new power supply fixed. Basically, the +5v PS ON is looking for an earth (-ve). When you push the button, this earths that pin and the PC locks it down to earth via software switch. Also, I would say that the other +5V you found is the 5volt feed for the standby circuitry. Short that and it will kill the power supply. Really, it is not worth the hassle, or a chance of stuffing your motherboard. See if you can borrow a power supply to try.	Pheonix (280)
144035	2003-05-14 22:06:00	I shutdown by using the Windows Start|Shutdown|Shutdown the computer? software method. The system shuts down and the LED goes fromn steady on to pulsing. It has always been thus.	James Kirk (3742)
144036	2003-05-14 22:12:00	Thanks, I'll follw your advice . The main difficulty in trouble-shhoting this probelm is that it is intermittant . All will be well for a few days, then the computer will refuse to start up unexpectedly . And as I don't know the details of how this power-up is supposed to work it is a bit hard to be sure of anything . The power supply is a retrofit as the original one blew up late last year when the mains power was restored after a power outage . So it would still be under warranty, but hard to convince the supplier when it works most times . I'll try another (borrowed) power unit . And, yes, I'm a bit scared about shorting the 5VDC rail .	James Kirk (3742)
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