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Power supply buzzing, please help!

Last response: in Components
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July 9, 2010 4:31:47 AM

Okay, so.

My computer was running and I accidentally unplugged the power cord. Since I wasn't doing anything important at the moment, I left it unplugged. When i plugged it back in and started it up, it made a weird electrical buzzing noise and Windows didn't boot up. I opened my computer and found that the psu gets hot, too, but I don't know if that's normal or not. Is my psu shot, or is it my cable? Please answer soon!

More about : power supply buzzing

a b ) Power supply
July 9, 2010 5:16:09 AM

A cable is just a cable. You either get power, or your don't.
Did you see the bios screen?
Is the power light on the motherboard on?
Maybe you knocked something loose when you shook the computer?
Where is the buzzing noise coming from?
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July 9, 2010 5:29:35 AM

I thought maybe the cable may have gotten damaged and can't provide enough power.
The BIOS screen doesn't come up.
A light does come on in the mobo, dunno if it's the power light.
Nothing came loose, that I can see at least.
The noise is coming from the psu itself.
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a b ) Power supply
July 9, 2010 5:41:20 AM

FreakedOutTechie said:
I thought maybe the cable may have gotten damaged and can't provide enough power.

Only if by the damage somehow changed the wire guage to a thinner guage that couldn't handle 5A :p 

Well, if there is a light on your motherboard, then your motherboard is getting power. But the screen never gets any input. I really can't think of anything that could have happened to it caused by tripping the cord out but I'm going to say the first thing you should try is another PSU. If you have a friend with a PSU you could borrow, that would be great for testing. If that's not an issue, then we'll start looking at other components unless someone else can think of something I missed. By the way, what brand and model of power supply is it?
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a c 144 ) Power supply
July 9, 2010 5:42:32 AM

What kind of PSU?

The light on the motherboard is a standby power indicator. Basically, all it tells you is that the PSU is receiving power from the wall. It has nothing to do with the main power producing circuits in the PSU.

Our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...

I'd guess the PSU is dead. The best way to check a PSU is to borrow a known good PSU. If you cannot do that, borrow a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.
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July 9, 2010 6:37:13 AM

enzo matrix said:
Only if by the damage somehow changed the wire guage to a thinner guage that couldn't handle 5A :p 

Well, if there is a light on your motherboard, then your motherboard is getting power. But the screen never gets any input. I really can't think of anything that could have happened to it caused by tripping the cord out but I'm going to say the first thing you should try is another PSU. If you have a friend with a PSU you could borrow, that would be great for testing. If that's not an issue, then we'll start looking at other components unless someone else can think of something I missed. By the way, what brand and model of power supply is it?


Manufactured by Sparkle Power Int'l Ltd. Model FSP460-60GLN.
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July 9, 2010 6:47:10 AM

jsc said:
What kind of PSU?

The light on the motherboard is a standby power indicator. Basically, all it tells you is that the PSU is receiving power from the wall. It has nothing to do with the main power producing circuits in the PSU.

Our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...

I'd guess the PSU is dead. The best way to check a PSU is to borrow a known good PSU. If you cannot do that, borrow a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.


Well, I guess my PSU is shot, since none of that is really possible from a simple wall unplug, the computer was manufactured by a company. I have a couple of PSUs I could try, the first and most readily available might not be good, it came from a computer where the power came on, the fan spun, but it never booted up. Meh. The second one is in my brother's computer, but he got a better one but hasn't set it up yet. Oh well.
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a b ) Power supply
July 9, 2010 5:14:03 PM

FSP and SPARKLE both SUck! crap + crap = supercrap!
yeah i would say the psu is fried.
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a b ) Power supply
July 9, 2010 7:56:06 PM

shovenose said:
FSP and SPARKLE both SUck! crap + crap = supercrap!
yeah i would say the psu is fried.

Don't know about FSP but sparkle in the low end is good. Quiet fans too.
The model he mentioned actually appears to be a "Fortron"

it came from a computer where the power came on, the fan spun, but it never booted up
Unlikely that it is a PSU problem. More likely CPU, motherboard or RAM.
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a b ) Power supply
July 9, 2010 8:07:38 PM

2136376,9,511008 said:
Don't know about FSP but sparkle in the low end is good. Quiet fans too.
The model he mentioned actually appears to be a "Fortron"yep
said:


fsp=fortron source power
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July 9, 2010 9:58:57 PM

enzo matrix said:
Don't know about FSP but sparkle in the low end is good. Quiet fans too.
The model he mentioned actually appears to be a "Fortron"

it came from a computer where the power came on, the fan spun, but it never booted up
Unlikely that it is a PSU problem. More likely CPU, motherboard or RAM.


After installing the PSU from the other computer, the result hailed the same, turning on but not booting. Harumph.

Edit:
I installed the psu from the computer that worked for sure but the fan never quieted down and I never got video. Maybe the first replacement wasn't bad...

Original psu watts: 460

First replacement specs:
Manufactured by Hipro, model HP-P3527F3, "max output 300 watts"

Second replacement specs:
Manufactured by Dell, model NPS-250KB D, "max combined power on +5V and +3.3V output is 170 watts"
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