# Breakin' short circuit protection.

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Hiiii guys!

I've got a free 500W PSU from my old computer. Now i wanna use it for lead soldering. The problem is: it's short circuit protection is soooooooo god enough to make I mad. I just need a +3.3 V (27A max) and GND.

So guys, plz answer me how to break the short circuit protection.

PS:
- Don't say me waste -@- !!!:_)
- Don't tell me about warnings, etc.!!!1

a b ) Power supply

I ussually to tap out by solder the wire to the rail, turn it on by simple switch...
(I used it to power mini vacum cleaner  )

what do u means by "use it for lead soldering"? (my English not so good)

Dunno if "use it for lead soldering" could trigger the short circuit protection...
a b ) Power supply

You must be using a load less than 0.12 ohm to trip the short circuit protection...
Simply put if you were to disable short circuit protection and then attempt to draw more power out of the supply than intended, you'd probably start a fire..
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a c 104 ) Power supply

I believe he wants to use it to power a soldering gun, and as stated, noone with sense is going to assist in this potentially fatal exercise
Moto
a b ) Power supply

Motopsychojdn said:
I believe he wants to use it to power a soldering gun, and as stated, noone with sense is going to assist in this potentially fatal exercise
Moto

Ho, I see now..
well it normal for people who study electrical engineering in my area to temper with fire/electrical hazard circuit, but precaution and right tools is a must, it dangerous...

popatim said:
You must be using a load less than 0.12 ohm to trip the short circuit protection...
Simply put if you were to disable short circuit protection and then attempt to draw more power out of the supply than intended, you'd probably start a fire..

good point, just add simple high power 1 K / 500 ohm resistor could do the trick...

U mean: add a resistor (1K / 500 ohm) in series to the circuit?
didn't u?
a b ) Power supply

yup, but make sure it high power ones....

the heat and power will move to the resistor, if it not adequete, the resistor will POP!! or something like that.

Make sure u had proper equipment for safety reason. (event u said don't tell u about safety, but i had to.... for peace of mind sake  , so if anything goes wrong i'll said "I told u so" wkwkkwk. joking )

edit: are u using it to power soldering gun? as i'm remember the heat is generated by/because AC voltage, the DC voltage need to be inverted so why using the PSU??
a b ) Power supply

rdc85 said:
good point, just add simple high power 1 K / 500 ohm resistor could do the trick...

500 ohms on 12V rail is under 1/2W, nobody is going to be able to solder anything with that.

If the OP's PSU can provide 27A on 3.3V rail and he wants to use that for conduction welding, he could use a 10W 0.12 ohm resistor in series with his welding tips but 20ish amps are not likely to be enough for that.

The simpler and "safer" way to do it would be to take a microwave transformer, remove the HV winding and replace it with 2-3 turns of the heaviest gauge cable that will fit.
a b ) Power supply

InvalidError said:
500 ohms on 12V rail is under 1/2W, nobody is going to be able to solder anything with that.

If the OP's PSU can provide 27A on 3.3V rail and he wants to use that for conduction welding, he could use a 10W 0.12 ohm resistor in series with his welding tips but 20ish amps are not likely to be enough for that.

The simpler and "safer" way to do it would be to take a microwave transformer, remove the HV winding and replace it with 2-3 turns of the heaviest gauge cable that will fit.

I see, good one..

so the best bet is using 0.12 ohm resistor to draw out the psu power....
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