View Full Version : PSU Problems

14-10-2004, 11:27 AM
A mates P4 computer has stopped dead in its tracks. By that I mean we have no power.

I知 sure I can see the fan give a little flick when the power on button is pushed but that is it.

A check of spare power plugs with a multimeter shows no voltage anywhere.

Now I know these darn things have a power made good wire so I知 wondering where to start?

Can someone give me the standard procedure for testing these things please?

The PSU is a Hairong ATX-400w.



14-10-2004, 11:37 AM
disconnect the output plugs from the psu to the motherboard/drives etc.......then take the large plug that has about 20 connectors on it and supplies the main power to the mobo and look at it.....you'll see near the middle theres a few black wires and a green one........use a bent paperclip or similar to make a connection between the green and one black.........this should kick the psu into life.........if it dont then theres a problem with the psu if it does then theres a problem on the mobo perhaps

Pete O\'Neil
14-10-2004, 11:42 AM
Im just gonna bite my tougue and not say anything about the quality of Hairong PSU's ;) Wouldnt surprise me if it was dead.

14-10-2004, 12:27 PM
Thanks for that drcspy. That fired up the fan and we now have correct voltage without any load. Further testing pending.

One thing though is I opened up the unit whilst waiting for replies and fair go I致e never seen so many dry joints in my life. The solder they used looks more like oxidised aluminium. I知 not impressed!

Soooo, I値l fix the dry joints and take it from there. Probably solve the problem.



PS Just seen your post Pete, yes, no need to bite your tongue, yeee gods their rough!!

Graham L
14-10-2004, 02:31 PM
You might be seeing the effects of lead-free solder. Tin-lead might be alleged to be nasty but it works.

Murray P
14-10-2004, 03:27 PM
Would it still be under warranty BM?

Cheers Murray P

14-10-2004, 05:01 PM
I知 sure your right Graham. The solder today is rubbish. I think the good stuff had a bit of antimony in it for good measure. Anyway, the repairs have been made with 1960痴 vintage solder complete with corrosive flux! :D

Now, whilst we have power, we also have problems. All voltages are within the limits that I致e found except the +3.3v. This reads 4.63v on my digital meter and 4.41 on my analogue meter. Plus, it wobbles around 0.3 to 0.4volts. I hung a tail light bulb across it to see if a load helped but no.

I figure I have a problem here and the motherboard is not appreciating the extra volts.
My reference gives the limits for this supply as 3.14v 3.47v so would anybody like to confirm this.

Personally, I have severe reservations about the integrity of this PSU so would anybody like to recommend a make and model as a replacement.



PS Not now Murray :D