asus p4v8x need advise

[yonu]

ok I need some advice on a board that I had come in today it will not turn on according to be post card the 3.3 rail is on that is it well after I cleaned the nice thick layer of dust off the board well nothing looked bulged but I figured I would go ahead and recap it anyways so I replaced the 4 16v 1500uf caps and 6.3v 3300uf. After replacing then all it is still a no go. Should I assume it is a dead board and tell the customer to upgrade or is there something else on the board I can check?

Thanks,
yonu

[c_hegge]

Re: asus p4v8x need advise

All I can think of is replacing the smaller caps (1000uF). If it still doesn't work I would just say its dead and advise an upgrade.

[yonu]

Re: asus p4v8x need advise

any particular caps below 1000 or all of them?

[momaka]

Re: asus p4v8x need advise

Here's a couple of things to try if you haven't checked them already:
Start with a known good power supply from a reputable brand, and make sure the 4-pin CPU power plug is connected.
Check to see if the southbridge is functioning - that is, turn on the computer with the power button, then turn it off by holding the power button. If it turns on/off properly, it means southbridge is working. Check it's temperature too - it should feel warm.
Take out RAM and see if the motherboard beeps or gives an error message - if it does, try a stick of RAM that you know is good.
Make sure CPU heatsink is not loose.
Make sure CMOS RESET jumper is not in the shorted (reset) position.
Reset BIOS.
Double-check your solder joints again.

Also, with what brand and series of caps did you replace the old ones?

[yonu]

Re: asus p4v8x need advise

I have tryed most of what you listed however it doesn't attempt to turn on fans or anything

[momaka]

Re: asus p4v8x need advise

Oh so the fans don't spin at all? Do they "pulse" once as soon as you hit the power button?
If so, then it's possible that there's a shorted Mosfet on the board. There's probably a tutorial on here somewhere that instructs how to check for shorted Mosfets.
You can also check to see if any of the rails on the motherboard are shorted to ground. With a multimeter set to check resistance, put one probe on ground and move the other probe around the 3.3v, 5v, 12v, and 5vsb rails (with the PSU off and disconnected from the motherboard). If there's 0 or very low resistance between one of the rails and ground, it's possible that there's a shorted Mosfet somewhere on that rail.

Also, what caps were originally on the board and with what brand and series did you replace them?

[yonu]

Re: asus p4v8x need advise

ok they don't pulse or anything i will have to double check the brand on the caps as I picked up what our local wannabe electronics supply shop had.