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Old Computer PSU

Chat_Ghosty

Jun 30, 2012
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I have a few Old Computer PSU. Is there internal parts that I can keep for Future projects?
I don't have much money. So I need to cut costs. (Like we have never heard that before)
 

davenn

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Sep 5, 2009
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yup lots of parts in there capacitors, resistors, power transistors and diodes, bridge rectifier to name a few

Dave
 

Chat_Ghosty

Jun 30, 2012
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What would be the best way to remove these without Damaging the Part?

I have a Old De-Soldering Kit from the 70s. Will that work? Or would I need something more Specific?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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If the old power supplies work, they can be used as... power supplies!

If you don't have mains wiring experience, I could not recommend any of the projects on the web that require you to take them apart and rewire them internally, but there is still plenty or scope for using them and keeping them sealed.

Some important points to note:


  1. A supply with its own power switch is probably best to start with
  2. You will almost certainly have to investigate which signal must be used to turn the power supply on (one wire is used for this purpose)
  3. You may have to put a load on the 5V rail to ensure the others are stable. If you can find a PSU that doesn't need this, all the better.
Apart from that, there are some parts inside most switch-mode supplies you can re-use, but frankly, not a huge amount.


There are:

  • Several high current, low voltage rectifier diodes.
  • A high voltage (generally 400V+) MOSFET
  • An optocoupler
  • Some low ESR capacitors (probably near end of life)
  • A mains filter
  • A SMPS controller chip, and a high frequency transformer that you probably will never re-use.
  • Mains rated rectifier
  • 400V (ish) capacitor (that will bite you if the power supply has been plugged in recently -- which can mean in the last week or so)
  • Various assorted components.
 

Chat_Ghosty

Jun 30, 2012
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I know that there is a 12v and 5v Rail. Connecting the Green Wire to Ground always turns on the PSU. As of unstable, I am able to Run Hard Drives and Cd Drives Normal.

Could It be modified it to run at 18V and not 5v and 12v?

I have a old PSU from the Early 90s that has a Switch.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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These power supplies can be modified for a slightly higher output (remember my previous note about mains wiring), but 18V is almost certainly going to be higher than they're capable of.

Note that these power supplies have some negative voltage rails (they may have a -5V and/or -12V. In combination with the +ve rails you'll be able to get voltages in the range your after.

Be aware that the current you can draw from the negative supply rails is often very low. The power supply will normally have the current limits printed on it.
 

Chat_Ghosty

Jun 30, 2012
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I see. Would say 14 Volts be more Possible? If so, I could use something like that in my PSU Project?

I have two extra Computer PSU I can use. I'm going with the least Oldest and less hard to find.

That being said. The side of it reads:

200W

+12V - 6A Max
+5V - 18A Max
+3.3V - 10A Max
-5V - 0.3A Max
-12V - 0.3A Max
+5VSB - 1.7A Max

Unless all PSU have that Specific Volts and Current Ratings. Then it's almost like they are begging me to Mod this, :p

All jokes aside, I see what you mean about not being able to pull much Current from the Negative Rails.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Google for "modifying computer power supplies" and you'll find thinks like this.
 
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