Antec Neopower 480 issue

[alexpez]

Hi, let me start by saying hello (my first post).

Whilst using my PC recently I suffered from a power outage, which, when it was reinstated, seemed to leave my computer terminally ill. After a day of being unable to restart my PC I tried the on switch again and found to my suprise that it powered itself back up. Then i powered it down correctly, and it has yet to power back up

I have an Antec Neopower 480 PSU that has served me well for the past year and a half powering an Asus A8N SLI deluxe mobo.

When i switch the PSU power switch to ON, a green LED on the mobo lights up, but the on switch on the front of the PC will not start the computer anymore (since the power outage).

I have disconnected the PSU from the mobo, and, when connecting the Green wire to an Earth, the PSU fan spins up.

I then tried plugging the PSU back into the mobo (its an ATX 2 24 pin connector), and connected the Green wire to the Earth again (by slipping a wire down into the connector), but the PSU fan would not start up, and neither would the PC.

I have access to a multimeter tomorrow night (im in UK), and will attempt to measure voltages coming from this PSU, but am unsure of what exactly im supposed to be looking for. Could anyone give me some pointers on what i should be checking in regards to a 24 pin ATX 2 connector?

The research ive carried out so far (im a hobbyist computer builder, dont know much about PSUs) seems to indicate that if the PSU fan spins up when connecting the Green and Black wires when not connected to the mobo, then the PSU is fine and the problem lies with the mobo, but id really like to isolate the issue if possible and replace only the faulty item, and not both my mobo and my PSU.

Thanks in advance for any help and advice,

Alex

[Operandi]

Re: Antec Neopower 480 issue

The research ive carried out so far (im a hobbyist computer builder, dont know much about PSUs) seems to indicate that if the PSU fan spins up when connecting the Green and Black wires when not connected to the mobo, then the PSU is fine and the problem lies with the mobo

Usually that is the case, but I've had bad PSUs that would power themselves up but not supply proper power to boot the rest of the system. My first suspect would be the PSU, then the motherboard.

[gonzo0815]

Re: Antec Neopower 480 issue

Test it with onlky the pure motherboard, wohout any other component. If possible underklocl the cpu and may be even pull the gfx card. If it stats running that way, it is the psu. If you have any older system, may be only the board +cpu, you can use this for the test. If the psu is fine with light loads, it has cranked out caps or any other faliure.

[alexpez]

Re: Antec Neopower 480 issue

Thanks for the tips so far.

Ive used the multimeter on the PSU. My findings are as follows:

With a jumper cable between the green and black to turn on the PSU away from the motherboard, i flicked the PSUs ON switch and i registered correct voltages at every pin of the 24pin ATX 2 connector. I registered correct voltages at every pin out of the PSU. The PSU fan started to spin as soon as i flicked the ON switch.

I then connected the 24pin ATX 2 connector to the motherboard, jumped the Green and Black wires, and flicked the PSUs ON switch. The Green LED on the ASUS motherboard lit up, but the PSU fan did not start to spin. I tested several pin outs and didnt register any voltage at all.

Shouldnt i get at least something, even if its far lower than what it should be?

What else could stop the PSU from powering up correctly? Ive read something about a CPU fan sensor, which, if it fails, can be sensed by the PSU which will stop it powering up. Is that true?

Many thanks so far,

Alex

[alexpez]

Re: Antec Neopower 480 issue

I have also tested it with the 24pin connector attached to the mobo, and only a CPU on the mobo. When i flicked the ON switch at the back of the PSU the green mobo LED lit up, but the PC would not start (no fans or beeps).

Whilst the 24 pin connector was attached to the mobo, i measured only 0.04V at the 5V line. Does that indicate that under any kind of load the PSU is failing (it reads 5.01V when the 24 pin connector isnt attached to the mobo)?

Alex

[alexpez]

Re: Antec Neopower 480 issue

Ive also noticed that if i plug an old COMPAQ/HP keyboard into the PS2 on the back of the mobo, and flick the switch on the PSU, all of the keyboards LEDs light up (Num Lock, Scroll Lock, and Caps Lock and the SLEEP/standby button).

I then tried it with a standard (no sleep button) keyboard and the LEDs for caps, num and scroll just flash and then go out.

Alex

[gonzo0815]

Re: Antec Neopower 480 issue

May be the 5v SB section has gone bad. This is very common for many PSu`s. Even expensive units. The 5v Sb is a seperate circuit, wich is independent from the other rails. It provides the start current for the other psu sektions and supplying anything, wich should be on during SB or suspend modes etc. On some boards you can decide by jumper to suply the usb and keybord either from SB rail or from the normal 5v rail. To figure it out, i would suggest to open the psu unless there is warranty left. Then search for bulged caps, may be they are not the biggest ones (on 5v sb there is usually 2x 470uF to 1000uF). All bad 5v sb caps i pulled from PSu`s have had severe signs of failure. Unles you can`t test the psu either with a dummy load (may be some old harddisk`s) or a other rig, there is not mutch to say. With no seriouse load, there is no way to know what is realy buggy.