Sproggy Psu Problem

**480TURBO** · 11-18-2004, 01:28 PM

Hi all, i had a bad solder joint in my sproggy mk3.5 so i took it out of the car to repair it. fixed the problem and connected it up to a small 12v lead acid battery to test it. problem is i got the terminals mixed up and reversed the polarity. there was a smell of smoke and now it doesnt do anything at all.

can anyone tell me what is likely to be damaged by reverse polarity and what to test first. i think it might be something simple, the relay coil is ok cos when i apply 12v to that it clicks open and shut. when i hold the relay contacts closed the mobo fan starts up and the lights come on but it doesnt boot. i tested the voltages at the atx connector with the relay held closed and all the 12v, 5v etc are fine.

HELP!

**Tidder** · 11-18-2004, 01:40 PM

Probably the power good signal isn't getting generated. I don't know how to fix, but I bet that's the problem if all voltages test good.

**MatrixPC** · 11-18-2004, 01:46 PM

Did it work before the repair?
Like Tidder said, what is the voltage on all connectors? Power Good, StandBy, 3.3V, 5.0V, 12V, -12V, -5V?

**480TURBO** · 11-18-2004, 02:56 PM

yep, it worked fine but was working intermittently due to the bad solder joint. is the PG signal sent from the psu to the mobo before the psu will power up?
does the standby signal switch off when the mobo powers up?
cheers guys!

**Tidder** · 11-18-2004, 08:11 PM

The PG signal is sent after the power supply obtains a steady voltage. The motherboard waits for the PG signal before it starts the POST as far as I know. But I think it kicks on all the constants, 12v, 5v, 3.3v before it POSTs. That's probably why the fans spin but nobody's home.

**Tidder** · 11-18-2004, 08:12 PM

Wait a minute, wait a minute...

When you were testing your power supply, did you have the motherboard connected when you reversed the polarity?? If so, your mobo is probably dead. I'm suprised I didn't think of this before. Do you have another motherboard you can test?

**Tidder** · 11-18-2004, 08:15 PM

Here's a good website to check out...

http://www.pcguide.com/ref/power/sup...werGood-c.html

http://www.pcguide.com/ref/power/sup/func.htm

**480TURBO** · 11-19-2004, 06:30 PM

there is no power at the green wire on the mobo connector, i think i might have blown the transistor for the power good.
sounds stupid but i cant honestly remember if i had the mobo connected or not, i was so annoyed at reversing the polarity! i doubt that it was connected though as i hadnt traced the faulty solder join at that point.

**Tidder** · 11-19-2004, 06:34 PM

Well, you could always just jumper a 5v to the Power good and see if your mobo POSTs.

**Mastero** · 11-21-2004, 12:58 PM

Hey dont mess it up ... its just the IN4007 diode near the relay that might have gone boom ! ..

And please if any one has a problem use pictures to explane its easier to get to the problem .....

Look care fully at all the parts on the start part ... and see where you can see burn marks and check which one is smelling ... !

Good Luck
Mastero