Computer won't switch on!!

[madon37s]

Hi,

 

I have an older computer with Windows 7 on that I wish to give to a friend as he can't afford a new one but I have been having a problem with it!

 

Originally the computer worked fine on it's own but I then connected a KVM switch to it so I could use the same monitor as the new computer I had bought and it seemed to work fine for a while, I then didn't really use the older computer for many months after that and when I came to use it and switched it on nothing happened! no sound of any kind not even the internal fans. I thought it was the PSU so I bought another one for it (exactly the same type etc) but to my surprise and annoyance the computer did the same thing!! NOTHING!!

 

I have opened the computer back up and when I switch it on there is still no sign of anything moving or making a noise but the weird thing is I have noticed that there is a small green indicator type light that is on when the power is put to the computer which seems to suggest that there must be power getting to the computer somehow isn't it?

 

Has anyone got any idea's please as I want to give it to my very needy friend but at the same time don't want to spend a fortune on it either as it is surplus to my requirements anyway.

 

Any help on this matter would be very welcome and I thank you in advance for any help given.

 

Regards. Madon37s.

[Ray1000]

Hi Madon

 

After reading your post I wondered what happens if you simply power a PSU up on the bench ... so I tried it on two spare ones ... and nothing happens ... it is evidently waiting for the computer to do something before even the cooling fan starts.

 

Ray

[Plastic Nev]

Hi to both, the power supply starts with a momentary connection between two of the lines on the big molex plug that fits on the motherboard, it is actually the line from the press button on the tower. Without looking it up I forget which two wires they are.

 

However, providing this new power supply is of the same type as the one you replaced, I am afraid it is sounding a lot like a motherboard fault.

 

You can do a simple test on the power supply if you have a multimeter, there are instructions in the forum magazine pages here :-

 

http://magazine.freepchelp.uk/test-a-power-supply-unit/

 

Some checks you can try if the power supply seems OK, is to remove the RAM modules, the connections to the CD/DVD drive, the connections to the hard drive and all other connections except that big plug I mentioned and the two wires from the start button, then turn on the power and press the start button, if at least the fans start up it may be some other component, if still no fans, it may be the motherboard itself.

 

If possible, completely remove the motherboard and place it on an insulating surface, a plastic table top, or dry card or paper will do, connect the big plug and the connection to the start button again and see if at least the CPU fan spins up then. If the motherboard has a BIOS beep speaker fitted, you should also hear a series of beeps.

If still nothing the motherboard is the main suspect.

 

Nev.

 

Oh and a PS, I still think steam engines are better. :D

[Ray1000]

Thanks Nev,

 

Ray

[madon37s]

Hi Nev,

 

Many thanks for your reply. Quite a bit to take in but I will have a look and see what I find out. Motherboard problem sounds terminal to me! That would be a great shame.

 

Madon37s

[Plastic Nev]

There is just the chance something such as the RAM, Disk drive, or other off board item, may just be a major fault and preventing the rest from starting up, hence why trying the board with everything disconnected.

If the fans spin up, and if a BIOS speaker is fitted you should hear many beeps, the next thing is turn off the power, and reconnect something and try again.

 

Nev.

[steve61]

Hi.

Not sure if you still have the problem.

Here's something to try.

If you can get the motherboard manual, it may make this a bit easier, but its not impossible without one.

Simply, remove the plug with the wires in that run from the board to the power, it is one of the small connectors that you push on when you put a new board in, the others are usually power LED, HDD LED, And reset switch.

When you have pulled it off, short the two pins on the board that it was pushed on to together with something small and metal, I usually use a small screwdriver.

If the PC starts, its a simple power switch fault.

If not then try pulling the reset switch plug, and short the power pins again.

don't worry about doing any damage, as long as you just short the two pins, it will be OK.

[madon37s]

Hi Steve,

 

Thanks for taking the time to reply. I have just recently took it to a local computer shop that built my new computer up for me to have a look at it as they said they would look at it for nothing which is very good of them I must say.

 

Anyway, the upshot of this is that basically the computer could have had a power surge in the past as the motherboard was totally dead and the power supply was fubar as well. They said it wouldn't be financially viable to try to repair it as I could probably buy a decent cheapish one for less!!

 

Thanks to all of you for your input and help. :D

[Plastic Nev]

Thanks for the update, a shame it is that bad, and very good of those guys to offer to look for nothing. A dealer worth using again no doubt.

 

The only thing left for it now is as a good heavy doorstop to keep the door open or shut perhaps. :D

 

If it is of any commiseration the same happened to my old and very first XP machine, a capacitor in the power supply blew which in turn took out the motherboard. KenB will remember that one as he helped in finding that out, which in turn got me into this computer fixing game, now over ten years ago.

 

Nev.

[steve61]

Remember when my first machine gave up the ghost. The modem went pop, and for some strange reason the only thing it took out was a 16mb memory stick.

I can tell you that Windows 98 would boot on 2mb of memory with a 486 cpu, until the desktop came up that is....

Its unfortunate really that, what is in age terms probably not that old a machine can be more expensive to repair than buying a new one.

Unless you want to walk around endless car boot sales in order to get a replacement board, and then take the risk that nothing else has died.