Author Topic: Computer not turning on-ing (Read 3443 times)

1gear · « **on:** 28 October, 2009, 09:31:17 pm »

Well, i took the computer out today after it had turned itself off. Took all the leads out the back, took the side off, brushed it out straight onto the floor, put the sides back on, leads in, and now it wont fricking turn on.
Ive not touched anything inside, just swept out the bottom and the side pannels that i had taken off, looked into the fan and blew into it abit, wiped the powersupply outer with my hand then put the sides back on.
It wont give me nothing. Ive checked everything is in the right place, checked insde for all the cables to be pushed in, checked the switch on the back, nothing.
Ive changed the fuse, but still nothing. I still need to check that and check that isnt faulty and check the cable aswell, but i cant find the black cable to my multi meter, i think my brother has stolen it or just moved it.

Any suggestions as to what i could have done? Ive taken the cables out from the back before and put them in fine but this time nothing

Any ideas? Luckily we have a laptop that i can use for tonight.
Cheers

Phil · « **Reply #1 on:** 28 October, 2009, 09:40:37 pm »

Have you accidentally turned the PSU power switch off? Sorry to start with the obvious, but nine times out of ten faults like these are wiring not hardware.

1gear · « **Reply #2 on:** 28 October, 2009, 09:51:22 pm »

Quote from: Phil on 28 October, 2009, 09:40:37 pm

Have you accidentally turned the PSU power switch off? Sorry to start with the obvious, but nine times out of ten faults like these are wiring not hardware.

Thats on the back of the computer, ive tried it in both positions.

(sorry if my spelling is bad, i dont have spell check on this computer and my spelling is terrible

)

tonycollinet · « **Reply #3 on:** 28 October, 2009, 10:00:05 pm »

Normally there is a fan inside the PSU - does that come on?

1gear · « **Reply #4 on:** 28 October, 2009, 10:04:32 pm »

Quote from: tonycollinet on 28 October, 2009, 10:00:05 pm

Normally there is a fan inside the PSU - does that come on?

No, nothing at all comes on

1gear · « **Reply #5 on:** 28 October, 2009, 10:08:10 pm »

If it helps to narrow it down, and for anyone that hasnt been on here looking, it has been just turning itself off sometimes, but the green power light stays on. It did it tonight for a strange reason, whilst virus scanning, did it monday whilst virus scanning, also yesterday and its done it before.
Gives no indecation something is wrong, it just goes, has done it when not virus scanning before

Phil · « **Reply #6 on:** 28 October, 2009, 10:14:00 pm »

If literally nothing happens - no lights, no whirring noises or beeps, nothing on the screen, then it's a power supply problem.

When the computer turned itself off before, did it display anything like a blue-screen error message or just go blank and stop working?

1gear · « **Reply #7 on:** 28 October, 2009, 10:25:35 pm »

Quote from: Phil on 28 October, 2009, 10:14:00 pm

If literally nothing happens - no lights, no whirring noises or beeps, nothing on the screen, then it's a power supply problem.

When the computer turned itself off before, did it display anything like a blue-screen error message or just go blank and stop working?

When it turned itself off before, it will be working fine at its usual speed, then the whirring noises of the fan and the screen will go, and it will be turned off, but the green power light will stay on. So basicly, the computer is off and needs turning back on, but the green power light is on. So i have to hold the power button, like im turning it off manually, then turn it back on. Which i first thought was a tempreture problem, but there didnt seem alot of dust in there, and i couldnt actually get to the power supply so couldnt touch anything in there.

tonycollinet · « **Reply #8 on:** 28 October, 2009, 10:56:41 pm »

It is probably a faulty PSU. There is an outside chance though that it is the motherboard. (There is a signal that goes back to the PSU to shut it down if the MB detects problems)

Do you have any chance to borrow a spare PSU - you wouldn't need to install it, just plug it in outside the PC case, and connect the power connector to the motherboard. You may even be able to do it if you can open a second PC, and transfer the PSU connector from the motherboard in the spare PC to the motherboard in your PC - you should also disconnect all the drive PSU connectors before you do it.

1gear · « **Reply #9 on:** 28 October, 2009, 11:15:50 pm »

Quote from: tonycollinet on 28 October, 2009, 10:56:41 pm

It is probably a faulty PSU. There is an outside chance though that it is the motherboard. (There is a signal that goes back to the PSU to shut it down if the MB detects problems)

Do you have any chance to borrow a spare PSU - you wouldn't need to install it, just plug it in outside the PC case, and connect the power connector to the motherboard. You may even be able to do it if you can open a second PC, and transfer the PSU connector from the motherboard in the spare PC to the motherboard in your PC - you should also disconnect all the drive PSU connectors before you do it.

Sadly not. May be able to take it to a computer shop tomorrow though, its been to them many times now.
Sadly no other proper computer in the house, just laptops.
So it could just be the PSU and it needs a new one? These arent expensive are they?

mercury · « **Reply #10 on:** 29 October, 2009, 12:24:09 am »

Check the power button on the outside of the case. If the power button is stuck down the computer will stay off.

Open the computer. Follow the power button's wire to the little two-pin connector on the motherboard. The connector on the motherboard is called the "ATX Power Switch Jumper". If the wire has fallen out of the motherboard, the power button will have no effect. If not, pull the wire out and poke a metal screwdriver into the jumper between the two pins. This will allow a tiny electrical current to flow across the two pins - it is called shorting the jumper - and should trigger the main power.

Look at the motherboard. Are there any LEDs lit? Look at the cylindrical objects which are called capacitors. They should all have flat and shiny tops. Not domed, pushed up and leaking brown stuff.

Try a power supply tester. Useful gadget allows you to check the power supply works when you have an unknown motherboard.

tonycollinet · « **Reply #11 on:** 29 October, 2009, 09:42:43 am »

Now given you've been in there with brushes - that is a good suggestion. Those little connectors fall off very easily.

Should have thought of that... Doh!

1gear · « **Reply #12 on:** 29 October, 2009, 10:16:15 am »

Kool, right ill give that a go in abit, trying to get the house lookm less messy for when my mum and dad come home from being away in the caravan. If it is the PSU then how hard are they to fit? The guy in the computer shop said it would be £55-£60 to have one supplied and fitted, bur £20 to just supply one. Is it just a case of unplugging all the wires for it in the computer, unbolting and putting the new one in?
Thanks for the help! Back to cleaning now

Phil · « **Reply #13 on:** 29 October, 2009, 11:07:39 am »

It's exactly as simple as you describe. Do double-check the power button is connected first though!

1gear · « **Reply #14 on:** 29 October, 2009, 11:19:12 am »

Quote from: Phil on 29 October, 2009, 11:07:39 am

It's exactly as simple as you describe. Do double-check the power button is connected first though!

Right then, cleaning is done!
Just took the side off the computer again, all capaciters are fine, no doming or brownstuff coming out, all nice and shiny metal tops
The switch cable is in, i pulled it out, then pushed it back in again and still nothing, took the leads off and held my screwdrivr between the 2 pins and nothing.
So is this obvious signs it is the power supply?
When i called the computer shop up and he said £55-£60 fitted, i asked him what happens for it to be that much when the power supply is only £20. He said they check everything, give it a brush out and fit the part, but ive already brushed it out(not much dust in there anyway, and didnt touch the main board but that isnt dusty. Everything else seems fine, its just the computer wont turn on.
Ill talk to my parents more about it when they get home, but im happy to fit one. It looks simple and straight forward, so i cant see the point in taking it to the computer shop, leaving it there and waiting for it to be done, when we could just go and get a power supply and have my fit it.
I take it the connectors are all the same, or different enough that you cant put one wire into the wrong thing, like putting a power wire tothe CD re-writer to something else? Or is there just one/a few plugs that going into the PSU?

Cheers

Phil · « **Reply #15 on:** 29 October, 2009, 11:27:24 am »

There are only a few plugs that go into the PSU, and you can't accidentally plug them into the wrong socket. It's pretty self-explanatory really. Good luck, and let us know how you get on

1gear · « **Reply #16 on:** 29 October, 2009, 04:02:48 pm »

Bad news

went and got a PSU from the computer shop, the old one had gone, they tested it and even cleaned abit out that i had missed. Took the new PSU home with the computer, plug it all in fine, no problem there but still wouldnt turn on. So we've taken it back, the new PSU has been tested and that is fine, so we have left it there for them to check out

not sure if it has gone completely, he said a chip could have gone or a power surge or something. Not sure what speed/chip it has in it so not sure how worth it will be to be repaired, hes said if its below a certain amount (about 2400/2800) then it might now be worth fixing, they have some other ones in pretty cheap, obviously a refurb from a business or whatever or at least the case is for £69. Not sure whats going to happen with it:( wont be happy if thats it for the computer becauswe of the length of time we have had it and its got setting on so we can print from laptop to computer which took us ages to sort out

ScumOfTheRoad · « **Reply #17 on:** 29 October, 2009, 04:25:58 pm »

Sounds like a dead motherboard to me.
Are you sure there are no beeping noises, and no lights at all coming on on the front of the case when you apply power?

The other thing to do is Google for the motherboard manual. Find the instructiosn for clearing or resetting the CMOS. This will involve either moving a jumper to conenct two pins, or shorting two solder pads with a screwdriver. Give that a try - you have nothing to lose.

1gear · « **Reply #18 on:** 29 October, 2009, 06:41:07 pm »

Ive tried jumping it and so has the guy from the computer shop but theres nothing, no lights, no fans on, no beeping. Calling up tomorrow to see whats happening with it, hoping i will have it back or have a computer by friday night so i can get on with work. It didnt sound so good for it tho

Phil · « **Reply #19 on:** 29 October, 2009, 07:13:52 pm »

Dead motherboard is my bet as well then.

Here's a thought though - when a processor fan stops working it can cause the processor to overheat. The motherboard detects this and hits the off switch to save the processor from damage. Could your processor fan have been stopping intermittently? That could lead to a knackered processor...

1gear · « **Reply #20 on:** 29 October, 2009, 07:44:34 pm »

Quote from: Phil on 29 October, 2009, 07:13:52 pm

Dead motherboard is my bet as well then.

Here's a thought though - when a processor fan stops working it can cause the processor to overheat. The motherboard detects this and hits the off switch to save the processor from damage. Could your processor fan have been stopping intermittently? That could lead to a knackered processor...

Maybe so, although i would have thought i would have heard it go quiet, but maybe not. Its not a quiet computer, but im not sure if i would have heard it or not. I do have music on, and a TV will be on in the room aswell so the sound of one fan going off or on and off might not be heard, but when i turn it off i normally hear the fan go off.
The new PSU had a wacking great big fan on the side aswell, the old one just had a small fan on the back.
The bit i missed cleaning, the guy had to take the fan off and give it a really good brush to get the gunk out. He said it had a sort of chewing gum, dusty bit going on, on the heat sink section. He came in and showed me which bit i had missed for next time.
The PSU that was already in it was tested and was found to be knackered, i was hoping it was just going to be a quick swap of the PSU and a £15 job, although it appears not so.
Neither mind though, so is life, and could maybe end up with a better or slightly upgraded computer at the end of it so not much can be bad.
Also had the single core, dual-core and quad core explained to us aswell which was pretty interesting.
The guy is completely crazy though but a good laugh. Thought about taking up smoking when smoking was banned in pubs ETC

tonycollinet · « **Reply #21 on:** 30 October, 2009, 12:54:42 pm »

Be carefull about what he is going to charge for fixing it.

You can have a new system box for not much these days.

(there are cheaper, but I selected on with 2GB ram)

1gear · « **Reply #22 on:** 30 October, 2009, 06:01:08 pm »

Here's an update, he took it apart, put it back together and its turning on

No idea what was wrong.
It does sometimes not load up though, it will do the Windows XP thing with the blue bar that goes across when loading, and it will sometimes freeze, so you have to turn it off then turn it back on.
Think we are going to call up again and see what they say about it.

Thanks for the help