Author Topic: Power switch / reset Switch Problem (Read 359 times)

Sparks · « **on:** September 11, 2005, 03:40:04 PM »

Looking for help as usual. My mums machine has developed an interesting fault. When I turn the PC on using the power switch I can hear the drive spin up and the fans start but no boot occurs (the monitor stays dark and the HD activity light stays on). If I then hit the reset switch the PC boots fine.

I know the Power switch is a soft switch but is it likely to be the power supply or the switch or the motherboard ?? Any ideas or ideas where I can faultfind (eg palces to look for grounds etc.

Any help appreciated.

Sparks

Sparks · « **Reply #1 on:** September 14, 2005, 04:37:40 AM »

Anyone ??

Schutt · « **Reply #2 on:** September 14, 2005, 10:28:39 AM »

With PC you really cant say sometimes.

I think this could be power supply but it could also be the hard drive.

Try it with the harddrive unplugged, do you get to the bios then?
Try with harddrive plugged but switched off in bios, does it boot from floppy then?

Try in the bios to switch boot up floppy seek on and put a in the list of bootable drives to front, does he seek on the floppy for a system?

Sorry i cant be of more help.

Skuzzy · « **Reply #3 on:** September 14, 2005, 10:41:37 AM »

It could be the power supply. The behavior suggests the initial load from a cold start is too high for the power supply to handle.

A capacitor in the power supply could be going bad.

Tricky one to catch though. If the HD is spinning up, it would suggest the 12V rail is healthy as the motor spinup normally hits the 12V rail (although on some of the newer drivers, they have started using the 5V rail).
If the power supply does not have individual support for each rail, unplugging the HD and powering it up might do the trick. If the BIOS post happens, then you can be pretty sure the power supply is about to go out.

If the power supply has individual rail support, it gets a bit trickier as removing power from the HD would not neccessarily allow the BIOS to post. You would need to remove any PCI cards, for example, and hope it is enough.

The fact the HD is spinning up says the motherboard relay is working as the power supply is definately kicking off.

If it were mine, I would think power supply is going bad, first.

Sparks · « **Reply #4 on:** September 14, 2005, 02:17:48 PM »

Thanks guys. Thats exactly the clues I was looking for to go hunting. It is an older machine so capacitors may be going on the Power supply. Really appreciate the info.

Sparks

Balsy · « **Reply #5 on:** September 14, 2005, 02:55:50 PM »

Check the flux capacitor first... shove some garbage (rotten apples etc... in there) and it'll power right up.

I saw it in a movie so I know it works.

Balsy

OOZ662 · « **Reply #6 on:** September 17, 2005, 06:44:29 PM »

Quote

Originally posted by Balsy
Check the flux capacitor first... shove some garbage (rotten apples etc... in there) and it'll power right up.

I saw it in a movie so I know it works.

Balsy

I always wanted to know why they had to call it "Back to the Future." That's an oxymoron...

MrRiplEy[H] · « **Reply #7 on:** September 18, 2005, 03:28:23 AM »

Maybe because they went to the past from the 'future' that was present time.

Anyways I had a similar problem with my PC once when I had more harddrives installed than my box could really take. One of the hd's was sitting on a plastic sheet at the bottom of the case. If any part of the hd contacted with the metal of the case the pc wouldn't boot untill after several resets.

My guess is that it got somehow short circuited enough to drain the voltage levels down.

SKurj · « **Reply #8 on:** September 18, 2005, 10:45:04 AM »

check mobo isn't shorted to chassis as well..

JTs · « **Reply #9 on:** September 19, 2005, 04:44:06 PM »

mr fusion replaced the flux capacitor so make sure the garbage goes there

Sparks · « **Reply #10 on:** September 20, 2005, 01:53:06 PM »

Found the problem. The motherboard was hosed. finally died totally and when I went to put the new LVPS in I noticed three blown capacitors on the Main board (leaking electrolyte).

I think it had been caused by a surge during a thunderstorm some time ago and it had taken a while for the caps to dry out completely as the machine isn#t used that much.

Oh well new machine time

Thanks for all the help guys.

Balsy · « **Reply #11 on:** September 20, 2005, 02:02:45 PM »

Thats not electrolyte thats tomato juice from the tomatos you through in the Flux Capacitor.

I specifically said rotten apples.

Balsy

x0847Marine · « **Reply #12 on:** September 20, 2005, 06:00:43 PM »

Quote

Originally posted by Sparks
Anyone ??

So it will not boot into Windows by pressing the power on button, but will boot when you press the 'reset' button as it's in the process of not booting..

Did I get that right?

Are you ok with going into the BIOS?, there's one way to test the power buttons on your tower... if your keyboard has a "power" button, you can set the BIOS to turn the system on via the keyboard.

Or if your BIOS supports it (mine does) you can disable all the "power" buttons and start Windows by typing a password...

I would also open the case and look for dust on the video card, fans etc... some mobos are smart and will not start to protect itself. A $2 can of compressed air can do wonders.

Also make sure the BIOS is up to date, many a time a problem like this is known and a fix released.
Something like this could have hundreds of causes depending on the brand of motherboard and BIOS, but ill bet ya it's a hardware problem for sure.