User Guides Guide to measure the Voltages of your Power Supply

Since information on measuring voltages of a Power Supply was often requested by members, SunMysore was kind enough to bring about a guide.

I'm posting it on Sunny's behalf, please direct all Reps/Comments his way :) (If you like the formatting, you can rep me :p )



Guide to Measure the Voltages of your Power Supply Unit

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Introduction: This is a guide to measure the voltages of your power supply using a Multimeter. The multimeter gives a more accurate measurement of the voltages than the motherboard software that indicates the voltages. This guide tells you how to measure the voltages of the +3.3V, +5V and +12V rails.

Stuff needed:

1. A long AWG16 wire

2. Digital Multimeter

3. Spare Hard disk power connector (Molex Connector)

Instructions:

How to use the multimeter :

1. Set the voltage range on the Multimeter to 20V DC.



2. Put the Black lead of the Multimeter into any of the Black ground wires of the molex connector.





Readying the 3.3V :

1. Take the long wire, and strip both ends as shown - one end with a short length of wire stripped, the other end with a longer length of wire stripped. Make a loop with the end having the longer length :







2. Remove the ATX motherboard connector. Here's a diagram showing the line voltages on various leads on the 20-pin ATX connector (tnx to Eazy)

11154a177d372edbe.jpg


3. Insert the short stripped end into the Pin 1 (Orange) as shown.



Push it firmly into the socket.



4. Replace the connector back to the motherboard.



5. Place the wire in a secure location, out of the reach of any metal.



Measuring the 3.3V :

1. Ready the Multimeter by following the instructions above.

2. Put the Red lead into the wire loop as shown.



3. The real 3.3V voltage will appear on the multimeter.





Measuring the 5V :

1. Ready the Multimeter by following the instructions above.

2. Put the Red lead into the Red pin of the molex connector.



3. The real 5V voltage will appear on the multimeter.





Measuring the 12V :

1. Ready the Multimeter by following the instructions above.

2. Put the Red lead into the Yellow pin of the molex connector.



3. The real 12V voltage will appear on the multimeter.

 
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Reactions: 5 people
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T

TheMask

Skilled
Jan 3, 2005
3,732
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thread rated.. sunny will rep ya once u make a reply here.. and btw, sorry mate.. this guide has been lying with me for over a month now and i cudnt post it..
 
Q

Quad Master

Skilled
Apr 17, 2005
5,301
259
222
Mumbai, IN
Sunny finally you have this guide on TE.
Remember we had a talk about this earlier.

Gr8 Guide will be helpful to many ppl out here.

Eddy Nice formating.

Thread Rated & Repped you
 
U

uknowme007

Disciple
Jun 5, 2005
161
0
0
Hey Matez,

Cud u plz tell me wats the AWG 16 wire...any other name for it ?

Is tht available in any electronic shop ?

Cheerz....

N. B ;

Gr8 piece of artivle and gr piece of editing ...very useful info and easy to read...

Tnx
 
SunnyBoi

SunnyBoi

Branch Manager
Staff member
Patron
Jan 31, 2005
4,853
1,978
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Bangalore
well....i dont know :S

but you can measure how mush AC current ur comp is drawing..r.equires 2 DMMs and one calculator :D

use one DMM as voltmeter, another as an ammeter. multiply the readings to get the total current drawn :)
 
Grease Monk

Grease Monk

Intertoob Ninja & Hamster Hunter Extraordinaire
Adept
May 21, 2005
964
45
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Chennai
your psu SHOUDNT be operating at 450W. If it is then it is at maximum load (and that would be bad for the psu). The psu provides as much power as the computer needs and not at the rated max capacity. The wattage depends on the number of devices connected to the psu. The more components...the higher the wattage. All you really have to worry about is your voltages being within the permissible range, and the sum power consumption of your components being LESS than 450W.
 
Crazy_Eddy

Crazy_Eddy

Staff member
Super Mod
Feb 7, 2005
8,887
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unknowme007 said:
Cud u plz tell me wats the AWG 16 wire...any other name for it ?
Is tht available in any electronic shop ?
Click to expand...
AWG = American Wire Guage . Its a standard for measuring the thickness of a wire.
AWG 16 = Wire which is roughly 1.3mm thick. In other words just look for a wire that is reasonably thick , not necessarily it has to be exactly 1.3 mm thick ;)

Thicker the wire = more current that can flow through it. However, measuring voltages with a multimeter does not need significant current draw through it, hence technically any thickness wire should be fine :)

rock_ya_baby said:
Hey sunny, is this guide incomplete or something? was wondering how do u calculate the watt put out by the PSU.. like my says 450W.. how do i calculate if its giving me 450W?
Click to expand...
The guide isnt incomplete. Its a guide to measure Voltages, not Wattages :)
Basically I guess you want to know if your PSU can output the full stated 450W capacity, right? To actually measure wattages output by a PSU would require pretty expensive high-end equipment - one that has the necessary resistive loads to fully load the PSU upto the rated capacity, and that normally exists only with PSU manufacturers.

Measuring wattage input to your PSU is relatively easier, as Sunny has outlined - though caution is advised in that case since you'll be working with direct AC high voltage. You can then guess-timate the approximate wattage your PSU is outputting to your system by taking into account your PSU efficiency (roughly around 60-70%, but this figure varies widely with PSU's and also varies with the amount it is loaded)
 
Rahul

Rahul

Skilled
Jun 11, 2005
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Chennai
my UPS can measure watt ....... mine runs @ 175-180w on mornal conditions .......@ 165-175 when i start the C&Q and my CPU is running @1Ghz ........@190 on load conditions prime95........@220 when o OC the processor to 250x9 with full load.......minus the 6600GT its running now @ 119w with CPU At 1ghz
 
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