MY pc wont turn on!! HELP!!!

[willawake]

Re: MY pc wont turn on!! HELP!!!

here's the 5 euro one. probes fell off eventually. still i havent purchased a digital multimeter that was rubbish and useless.

[Rainbow]

Re: MY pc wont turn on!! HELP!!!

I have this one, only it's marked DVM890L (IIRC). Something died there as it's showing some resistance on high ohms range even with leads disconnected. Tried to fix it but found nothing.

[christophicus]

Re: MY pc wont turn on!! HELP!!!

Right a Got one, It cosr €30 And is made by Draper (i dont think its a good quality make).

So is there any possibility that I can blow something with this?

[christophicus]

Re: MY pc wont turn on!! HELP!!!

Ok i justed tested it and the capaciors near teh CPU dont seem to have any voltage goingo across them. but the one that gets quite hot has about .82 volts. Is that alot?Or is it a little?

[christophicus]

Re: MY pc wont turn on!! HELP!!!

Ok so i couldnt get the capacitor off with the soldering iron, so i had to just brake it off. I managed to get a replacement capacitor though , so i hooked it up. That too is heating up very quickly and i still am not getting and noltage across the caps near the cpu.

Any suggestions or ideas?


by the way this is the multimeter i got.

[christophicus]

Re: MY pc wont turn on!! HELP!!!

ok so htere is 4.9 volts going through the pins for the power button,is taht NOrmall?? also its the whole area around the capacitor that is heating up aswell. Also does the fact taht the caps near teh CPU ahve no voltage goingo through them suggest that the CPU may be fried ? I think the board is pretty much a write off. what do you gouys think?

[willawake]

Re: MY pc wont turn on!! HELP!!!

yes it would be normal to have around 5v going through power button connector
looks like a nice multimeter

is the cpu fried? no idea. i think it would be safe to try it in another pc anyway.
there appears to be something wrong with the voltage regulation circuit on the board. i am guessing the 5v you are getting is coming unregulated thats why its ok. maybe the cpu damaged when that failure occurred or maybe not.

anybody have any ideas?

[starfury1]

Re: MY pc wont turn on!! HELP!!!

Firstly I am not familiar with this MB

working on the basis that;

1 the capacitor is in the right way
2 you have not created any solder bridges
3 your solder joints are ok
4 you did not damage the pcb when you got the old one off

I suspect its hanging across the 12 Volt line (you said 100uF 16V)

It location doesn't put it anywhere near CPU, close to the chip set by the looks of it.

It looking like (to me) you have a *short on the main pcb somewhere between +V supply, possibly 12 Volt rail

I don't know what effect a short would have on the PSU, as in I am not sure how it would shut down to protect its self if you short out the 12 volt rail.

*short circuit meaning 0 Ohms or very close to 0 ohms resistance between a + V supply and Ground (like putting a thick wire between the battery terminals of a car battery)

supply rails
Normally should be a high ohmic reading
(but that does depend on what is hanging between the supply rails and ground)

From the fact you say its heating up
(and not quite sure how the psu is dumping current if the supply is shut down..leave that one for those who know these things better then I)

1 how long before the cap and area of the pcb gets hot?
2 does the cap get hot first or the area surrounding it get hot first?
3 are any close by components getting hot first.

I am starting to suspect a possibly shorted pcb

you would need to check the supply rails for shorts or shorted supply type components I think.

Others here would be best to advise you on how to do this

Alternatively there would be posts on these forums about things to check and how to check.

HTH

[willawake]

Re: MY pc wont turn on!! HELP!!!

check your fets using the beep function on your multimeter
https://www.badcaps.net/forum/showthread.php?t=1441

[Fizzycapola]

Re: MY pc wont turn on!! HELP!!!

If you post photo's it may help. The guys here I've noticed are quite good at
spotting things problems in photo's.

I think there is a way to test the PSU by shorting it?

I've had computers not boot. I always presumed it was PSU or CPU, in testing
it had been one or the other, although it is possibly maybe ram module. My
computers that have had capacitor problems have had more intermittent
problems than just total failure. Also the guy who sold
you the system, saying the power button was connected the wrong way
around, sounds a bit suspect, I think the seller didn't know what he was
talking about.

You say you couldn't remove the capacitor and had to break it off. If you
heated both pins solder at the same time using 50-80w iron with wide tip it
should slide out easily, if the tip can't heat both then hold capacitor in
long nose pliers and incrementally slide each pin out (this takes very much
longer as you can only edge about half a millimeter of each pin at a time).
The benefit is you won't damage capacitor insert rings, which if damaged
is catastrophic.

If I were you, I'd start prospecting replacement parts on ebay (Socket-754
MB) as the most cost and time efficient solution. By having parts to do
testing with, you can find out exactly whats faulty, faulty items sell very
quickly on ebay, sometimes it doesn't seem to matter as long as it's cheaper
than the retail people don't mind if it doesn't work.