No power on switch on

  tdmoh 13:20 21 Nov 05
Locked

I have a Packard Bell . When I switch on theres no power . The 3 pin must be ok as the 3 pin out to the monitor is ok. I have opened the box but cannot see an internal fuse. Is there one & where is it? Thanks Tom

  Gongoozler 13:30 21 Nov 05

Hi Tom. It's very unusual for there to be a mains power fuse in a computer. If a computer fails to start when you press the power switch the fault could be in the power supply, the mother board or the power switch itself. How old is the computer, how familiar are you with the workings of a computer and how much are you prepared to dismantle yours?

  WhiteTruckMan 13:53 21 Nov 05

but all psu's are fused. they have those glass ones in them. in the good old days you used to be able to dismantle the psu and replace it, but now they are soldered in place. I know its a bit pedantic, but they are there, just not in a replaceable form. One possibility is to smell it. not definitive, i know but if it smells burnt then its probably rogered. I srtongly advise NOT trying to open it up and repair it. (if the fuse blew, it was for a reason)

only suggestion is to locate the 2 pins on the MB that are the power on pins (from the front panel switch) and CAREFULLY short them with a screwdriver, etc. if no power then new psu.

WTM

  ACOLYTE 14:05 21 Nov 05

Best thing to see if the on/off switch is faulty is to swop the headers with the reset switch and use this as an on/off switch if it boots its the on/off switch thats faulty,if not its a good chance the PSU has blown.

  Gongoozler 14:11 21 Nov 05

It's a fair cop WhiteTruckMan, I should have said that there it's very unusual for there to be a user replaceable fuse (except for people like me who are familiar with dismantling electronic equipment). I'm waiting for Tom to reply before giving any advice on diagnosing the problem, or recommending that the computer goes to the local repair shop.

  tdmoh 16:24 21 Nov 05

Thanks for the input guys. There is no reset button just power on. The power unit also holds a fan and looks " sealed"! PC is 3 years old. I have tried just pressing the power on button at the actual black dot switch( cover removed) But if PSU is blown how does the power get to the monitor? And if the motherboard is gone why doesn't the fan start?? I can change a plug & solder wires but is there stored electricity in the disconnected off PSU as in the back of a TV cabinet? ( A little knowledge can be a dangerous thing!!!) If all else fails I may try to just take out the hard disk & get the info that way. Thanks for all your responses so far. Tom

  Gongoozler 17:44 21 Nov 05

Hi Tom.The power to your monitor is a straight in and out of the computer mains. Power to rest of the computer is via the switched mode power supply. In this sort of supply the mains is rectified to produce a dc voltage. This dc is then converted to high frequency oscillations so that smaller transformers can be used to produce the various voltages the computer needs. Regulating circuits control the voltages to the accuracy required. The power switch at the front of the computer works at low voltage to control the power supply. If you have sufficient confidence you can safely short the two contacts of the front panel switch together to see if that works. The most likely part to have failed, however, is the power supply. This is fairly easy to replace - again if you have the ability and confidence to work inside the computer. You can get a new power supply for about £10 upwards click here.
I don't know of any way the average home user can diagnose whether it is the power supply or the motherboard that has failed, but if you want to tackle this yourself, I and other forum members will be happy to advise.

  tdmoh 16:47 23 Nov 05

Thank you for the offer but I'll take the hard disk out & put it in a caddy then get the info that way( the computer has now been replaced anyway. Thanks for all your help - I may be back for advice on hard drives !!!

  Fruit Bat /\0/\ 17:42 23 Nov 05

Any fan noises LEDSor other signs of life?

If not then 90% certainty its the PSU. (not new build)

Leds lit CD or HDD or fan noise then could be video card, memory, motherboard or CPU.

  woodchip 17:47 23 Nov 05

Even with fans and lights going the PSU still may be shot

  tdmoh 23:06 24 Nov 05

Thank you thank you. I'm now sure its the psu!!!
But I've taken out the hard drive put it in a usb caddy & now get access to all the files I needed & eventually an empty 40 gig extra hard drive for my new computer. But if any of you guys need a spare floppy or cd writer drive let me know!

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