Repairing a bad power supply?

All the computer repair books that iv read, say that if the power supply is bad just to "Buy a new one". I want to know if there is a way to fix them

Our computers power supply went dead on us about 6 months ago, and we just ordered a new one from Emachines. So I still have it, and am thinking about opening it up. I know your never supposed to open a power supply. but will the capacitors still hold electricity after 6 months? If I discharge the power it should be ok then right?

I asked my computer repair teacher about it and he said the "A fuse in the power supply probibly burned out".

Has anyone ever fixed one? Or is it posible...

thanks

 

wanna kill yourself.

 

It's far safer to buy a new one.

 

By now im assumeing I probibly shouldent try..

 

and ur assuming correct. repairing a power supply

 

lol, that about sums it up right there

 

My kid's Emachine used a standard off the shelf PSU, not sure why you needed to order one from them specifically. The last one I replaced for a friend was $10 after rebate. You can't replace too many individual components at that price. I usually open them up just to check for a simple fix like a fuse or wire. HOWEVER I'm an Electronics Technician in the Navy with over 20 years experience. AND I have access to a shorting probe to discharge the caps.

 

oh lol
well I dident realize it was that serious.

Project dropped.


thanks

 

Come on guys some basic electronics here, a computer power supply converts common household voltage of 110/220 AC to -/+ 12 v DC and less, the ripple caps are just that, with self bleed circuits thrown in. Now the power supply to your CRT Monitor is another story as it produces extremely HIGH VOLTAGE and the Capacitors can indeed take months to “Air Discharge”, they should never be touched by anyone except a qualified technician. THAT SAID 110/220 AC WILL KILL. A computer power supply off line and removed is a great electronic project to explore; after shorting the capacitors with an insulated screwdriver, you can follow the electron path with a simply Multi-meter and start to realize some basic principals of electronics.

THAT SAID, DO NOT POWER UP THE POWER SUPPLY OR PLUG IT INTO A WALL SOCKET, OR REINSTALL BACK INTO YOUR COMPUTER (That can ONLY be done by a certified electrician)

I miss the days when there were numerous Build your Own Electronic Magazines around, to explain the principals of Electronics to our youth, now it’s just Plug & Play, with know understanding of the basic principals.

 

lol I learned the hardway. I opened up a monitor to see if I could fix it. almost killed myself. had know idea about this thing called a capcitator till I touched it with a screwdriver. melted the plastic handle thing that saved my like and then the screen blew out. needless to say I nearly shit myself.

 

While I earnestly endorse the recommendations to NOT attempt to service your PSU yourself, I also agree with BCGray: information never hurts. If you're interested, you can download schematics for various PSUs' from this link.

 

Great link Mada Milty. Knowledge is Power, sorry just could not resist the pun

 

PSUs are just switched mode power supplies that convert AC mains voltage into a number of convenient smaller DC voltages for your motherboard; i.e. 3.3V, 5V and 12V.

What you've got to realise is that one side (generally (and should be) covered)) takes in the mains, and the other deals with distributing the smaller voltages by means of a transformer.

Basically the signal is retified (the negative parts of the sine wave made positive) and smoothed (made into a steady-ish line rather than a set of humps).

If you're interested you can always look at How Stuff Works for an easy explaination (http://computer.howstuffworks.com/power-supply.htm)

They can be fixed (it's generaly just a capacitor that's gone) but it's so unnecessary as you can pick them up from about £6-10 ($10-15).

The main things to realise are:

• NEVER WORK ON A PIECE OF EQUIPMENT LIVE (especially if it is faulty)

• Capacitors can hold charge for years.)

• Read about it if you're interested or get someone who knows what they're doing to show you which bit does what.)

Oh and never open up a CRT monitor like one of the guys did! There are serious voltages in the scan coils and EHT: we're talking up to 25,000 volts. Also the tubes are vacuums at very high pressures and so should be treated with a great deal of respect!