Need help testing ATX power supply

[Shawn]

My computer worked perfectly last night. I turned it off for the night and it won't start up today. I don't have any other ATX systems or I would just swap power supplies to see if that is the problem. Does anybody know how to test an ATX power supply with a voltmeter? I tested the power cable and it is delivering power to the back side of the power supply.

[Bleeding Edge]

3.3v pin11 pin1 3.3v
-12v pin12 pin2 3.3v
com pin13 pin3 com
pw-on pin14 pin4 5v
com pin15 pin5 com
com pin16 pin6 5v
com pin17 pin7 com
-5v pin18 pin8 pw-ok
5v pin19 pin9 5vsb
5v pin20 pin10 12v

Com is ground.
Pin1 is square shaped.
Place Negative lead of meter on Com.
Use positive lead to check pin voltages.

This didn't post right. You can still make it out.

[This message has been edited by Bleeding Edge (edited 03-29-99).]

[sql69]

just wondering what type of mainboard you were using...i'm experiencing a similar issue with a new a-bit bx6...have you tried to power it on from outside the case?

[Shawn]

I am using an ABIT BM6. It worked great for about 2 weeks. It just stopped working yesterday. Thanks for the input on the plug out. I will try to figure it out.

Is there any part of the power supply that should deliver power when the system is off? Like a standby power lead. All of the outputs from the supply seem dead when it is completely disconnected from the motherboard. Only connection is to the wall outlet. Should any of the leads have a reading and if so what color wires?

Thanks

[Bleeding Edge]

No. That's the function of pin14. The power-on pin. The switch on the front of the case is connected to the motherboard's power lead jumpers via a pair of wires. When the switch is pushed the motherboard sends the signal to pin14 to "feed me some power." It's then that the power is supplied to the connectors.

My previous post should read as four columns. [3.3v=pin11 pin1=3.3v] [-12v=pin12 pin2=3.3v] and so on.

[Myke]

The first time I used an atx ps,I thought it was dead until I found out that it had to be connected to the mb first.

After checking all the pins with my meter I found that there was only one pin that had a low votlage on it,>5v when the switch on the power supply was on.

That makes sense to me because something has to power the electronics on the mb for it to recognize when the power switch on the front is pressed

I'ts also possible that the power on sw is bad.
Short the pins on the mb and see what happens.

[This message has been edited by Myke (edited 03-31-99).]

[Bleeding Edge]

Forgot to mention pin9. sorry.

[Shawn]

Thanks for all the info. I verified it as a bad supply. I got in touch with the dealer I bought it from and he said he will trade it out. It has kind of sucked being without my new system for a week, but it is nice to know it should be running again by this weekend.

[NuovoTech]

Does anyone know how to jump across (or
whatever...) certain pins on power connector (when unplugged from board) to turn on PS? I've
heard this can be done...

[NuovoTech]

Found out to test PS unplugged, you jump pin 14
to ground. Pin 9 is always hot (+5VStandBy)...