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How do I test this PSU? Answered

I had got this PSU for free from PC world, the guy who gave this to me does not know if it works or not...

This is my first PSU, I never used one before...

So I am asking you how to test this PSU. I hear they have safety wires that must be connected to another wire or something - I don't know...

I hope you can help me... Thanks!

UPDATE
Yay! My PSU works :-)

Thank you all who helped me!

And even better, I do not need to use a power resistor to keep the PSU on!

Discussions

0
Plasmana
Plasmana

11 years ago

Then why does mine work without it?

0
thermoelectric
thermoelectric

Reply 11 years ago

It will work without it but its not good for it, like a car running without oil, it will go for a while and then...

0
Plasmana
Plasmana

Reply 11 years ago

Oh, okay, than I will add a load resistor on the 5v line.

I am going to use an 10Ω 5 watt resistor because:
5V ÷ 10R = 0.5I
so
5V x 0.5I = 2.5W
Using a 10Ω resistor across the 5v line will waste 0.5A or 2.5 watts of electricity.

0
thermoelectric
thermoelectric

Reply 11 years ago

Oh, Then the 10W 100ohm that i scavenged out of a emergency exit sign is too big?

0
Plasmana
Plasmana

Reply 11 years ago

No, the higher wattage is not a problem, it just saves space and money (if you are going to buy one).

0
thermoelectric
thermoelectric

Reply 11 years ago

Oh, When I put it on the 12v line it gets hot, but on the 5 volt, it rarely does anything

0
Plasmana
Plasmana

Reply 11 years ago

Equations...

12V ÷ 10R = 1.2I

then

12V x 1.2I = 14.4W

You were overloading the resistor on the 12 volt line, 14.4 watts was going through the 10 ohm resistor.

0
thermoelectric
thermoelectric

Reply 11 years ago

Okay.... I modded it and now the PSU turns on for a second then turns off, Troubleshooting time :-(

0
Plasmana
Plasmana

Reply 11 years ago

What did you do?

0
thermoelectric
thermoelectric

Reply 11 years ago

I just unsoldered the output wires and put in some other connectors,last time i tried it, it didn't turn on at all ;-(

0
Plasmana
Plasmana

Reply 11 years ago

Dang!

I really hate it when something goes wrong... :-(

0
thermoelectric
thermoelectric

Reply 11 years ago

Yeah ;-(, That was my biggest psu, 400 watt

0
Plasmana
Plasmana

Reply 11 years ago

Try undo your connections.

0
thermoelectric
thermoelectric

Reply 11 years ago

I know why it didn't turn on at all, i must of pulled the main off the power connector, I'll report back when i have done it

0
Plasmana
Plasmana

Reply 11 years ago

Okay.

0
thermoelectric
thermoelectric

Reply 11 years ago

I'll do that tonight.....

0
Plasmana
Plasmana

Reply 11 years ago

good...

0
thermoelectric
thermoelectric

Reply 11 years ago

Okay, I done it, It turns on but I need to keep tapping the signal wire with the ground for it to work, It used to work but now it needs to be pulsed..........

0
Plasmana
Plasmana

Reply 11 years ago

What! That is really weird... I guess you need to add in the 555 timer...

0
thermoelectric
thermoelectric

Reply 11 years ago

Yeah, a lot of my PSU's need to be pulsed, I just wonder what component was/is blown.......

0
Plasmana
Plasmana

Reply 11 years ago

lot of my PSU

I thought most of your PSU's are "blown", they just need to be pulsed to work?

0
thermoelectric
thermoelectric

Reply 11 years ago

Well I have a couple that do that (3 or 4) but i just think there's a blown component in there somewhere....

0
Plasmana
Plasmana

Reply 11 years ago

But witch one??? :-)

0
thermoelectric
thermoelectric

Reply 11 years ago

Yeah, Thats gonna take a day worth of full going troubleshooting

I'm guessing that it might be the LM339N Because that has been in every PSU i have ripped apart

0
NachoMahma
NachoMahma

Reply 11 years ago

. Having a higher W rating than required is not a problem.

0
thermoelectric
thermoelectric

Reply 11 years ago

Okay, The PSU is 400w anyway :-P

0
thermoelectric
thermoelectric

Reply 11 years ago

Yeah, That's good, I think...

0
Derin
Derin

Reply 11 years ago

??? I don't know

0
thermoelectric
thermoelectric

Reply 11 years ago

They will usually all work without it but they don't reach the output voltages until there is a load.....

0
thermoelectric
thermoelectric

11 years ago

Yeah, On the 5 or 12 volt side?

0
Plasmana
Plasmana

Reply 11 years ago

Usually on the 5 volt side.

0
thermoelectric
thermoelectric

11 years ago

The resistor might be a good idea, i think i sorta messed up the circutry inside a 400w one by not having a load

0
Plasmana
Plasmana

Reply 11 years ago

My 200 watts PSU does not need a power resistor, it works just fine.

0
thermoelectric
thermoelectric

Reply 11 years ago

I was saying it might be a good idea to always have a load there because i nearly burnt out my 400w psu by not having a load...

0
Plasmana
Plasmana

Reply 11 years ago

Why did your PSU nearly malfunctioned when there is no load resistor?

0
thermoelectric
thermoelectric

Reply 11 years ago

I don't know, i think just because it was a higher wattage or well i don't know, most people say to have a power resistor to keep a load or....

0
Plasmana
Plasmana

Reply 11 years ago

Yeah, it might be something to do with a higher wattage PSU...

0
Plasmana
Plasmana

11 years ago

Yeah, I did that same thing to my ATX PSU and it works like charm! With out using a power resistor!

0
carrierpilot1357
carrierpilot1357

Reply 11 years ago

same with me! no power resistor!

0
Plasmana
Plasmana

Reply 11 years ago

Thats cool!

0
NachoMahma
NachoMahma

11 years ago

. If it has a 20-pin connector, jumper the green wire to a black wire and it should power up. You may need to have a load on the PSU for it to stay on.

0
Plasmana
Plasmana

Reply 11 years ago

Thanks, and what about the gray wire called (P.G. SIGNAL)?

0
NachoMahma
NachoMahma

Reply 11 years ago

From http://pinouts.ru/Power/atxpower_pinout.shtml :
8 - PWR_OK - Gray - Power Ok is a status signal generated by the power supply to notify the computer that the DC operating voltages are within the ranges required for proper computer operation (+5 VDC when power is Ok)
. Shouldn't be needed for the PSU to run. It's to tell the mobo that the PSU is operating properly. If you don't have 5V on that line, the PSU thinks something is wrong with itself.

0
Plasmana
Plasmana

Reply 11 years ago

Wow, thank you for all of this helpful information, I am going to test my PSU tomorrow...

0
NachoMahma
NachoMahma

Reply 11 years ago

. Bookmark the Pinouts site - VERY handy.

0
Plasmana
Plasmana

Reply 11 years ago

Yes, I will.. Thanks! :-)

And my free PSU works! And I don't need a power resistor to keep it on! :-)

0
thermoelectric
thermoelectric

Reply 11 years ago

Yeah, That should work

0
guyfrom7up
guyfrom7up

Reply 11 years ago

yep, get a big fat 8 or 10 ohm resistor from radioshack (somethingg reater than 10 watts) and put it between +5 volts and ground.

0
Plasmana
Plasmana

Reply 11 years ago

Thanks!