Testing Your Power Supply With a Multimeter - Page 2

**TheMatt** · 09-29-2007, 03:51 PM

Added testing AC outlets. I will need help with the wording on distinguishing the power holes on the outlet from the ground hole.

Also, I have decided to divide the testing section up into these sections:

Testing AC voltage from the wall
Testing the power cord for resistance
Testing +3.3v/+5v rails from the PSU
Testing the various +12v rails from the PSU
Testing the Power_Good signal from the PSU
Testing the Power Switch for resistance

**mattlock** · 09-29-2007, 04:30 PM

Matt, nice article so far.

On standard grounded outlets in the US, if wired properly, the hot side of the circuit is the shorter slot and neutral (or grounded side) of the circuit is the longer slot. You may want to add how to test if the outlet is properly grounded and polarized correctly.

This is simple test. Insert the black probe into the round ground port and the red probe into the short slot. If you the reading is 115v then the outlet is grounded and polarized correctly.

Although, since this is an international website maybe you shouldn't include this info, since electrical outlet configurations vary widely throughout the world.

**TheMatt** · 09-29-2007, 05:02 PM

Matt - don't you usually insert it into the ground to test voltage, you use the hot and cold holes.

**mattlock** · 09-29-2007, 05:47 PM

Yes. Going across the hot and ground well give you the voltage reading, just as if you were going hot to neutral. The neutral and gruond are connect at the main panel. To test if the outlet is properly wired, you would perform the test as listed in my post. Anytime I'm testing an outlet, I go across all three, hot to ground and then hot to neutral for voltage, then ground to neutral for continuity.

The shorter slot of the outlet is supposed to be the hot side of the circuit. The longer slot is the neutral. If you go ground to the short slot and get a reading then outlet is wired and grounded properly. If you get no reading between the ground and the short slot but get a reading between the ground and longer slot the outlet is ground but not polarized properly.

This test isn't that important in relationship to testing the PSU however, it's just some added info for piece of mind.

Alot of homeowners simply install the pronged outlet so they don't have to use adapters but don't actually ground the outlet. Again, this info may not be relevant to your article, but thought I would throw it out there anyway.

**sandman55** · 09-30-2007, 01:16 AM

Hi Matt thats a very good tutorial

As an Electrician can I tell you the way electricity was explained to me and I have passed this on to apprentices under me.

A lot of people become confused with voltage and amperage and they cant see it. I tell them to think of electricity the way you would think of water going through pipes.

As the water pressure is the force pushing the water through the pipes example increase the pressure and you will push more water through the pipe.
Likewise the Voltage (EMF electromotive force) is the pushing force that pushes the current through the wires. Increase the voltage and you will push more current through the circuit.

Electrical resistance can be compared to partly closing a valve in the water circuit and that controls the amount of water that will flow. Likewise the resistor in an electrical circuit controls the amount of current flowing for a given voltage. You can have a fixed resistor or a variable one which is just like using a valve.

A diode can be compared to a check valve (non return valve) in a water circuit.

The diameter and also the length of a pipe have a bearing on the amount of resistance to the flow of water. But thats not so much of an issue in a computer case other than the cabling and any pins being of sufficient diameter to carry the current.

I hope you don't mind me giving my two bobs worth and if you can use any of it you may be able to word it better than I have, also you may not want to go into this sort of explanation thats ok too.

JohnthePilot · 09-30-2007, 02:59 AM

That's the analogy I was given as well.

**sandman55** · 09-30-2007, 03:38 AM

Great minds think alike

I won't say the second half of the quote

JohnthePilot · 09-30-2007, 04:11 AM

Quote:

Originally Posted by sandman55

Great minds think alike

I won't say the second half of the quote

"Fools...etc." LOL

**TheMatt** · 09-30-2007, 12:19 PM

Quote:

Originally Posted by sandman55

Hi Matt thats a very good tutorial

As an Electrician can I tell you the way electricity was explained to me and I have passed this on to apprentices under me.

A lot of people become confused with voltage and amperage and they cant see it. I tell them to think of electricity the way you would think of water going through pipes.

As the water pressure is the force pushing the water through the pipes example increase the pressure and you will push more water through the pipe.
Likewise the Voltage (EMF electromotive force) is the pushing force that pushes the current through the wires. Increase the voltage and you will push more current through the circuit.

Electrical resistance can be compared to partly closing a valve in the water circuit and that controls the amount of water that will flow. Likewise the resistor in an electrical circuit controls the amount of current flowing for a given voltage. You can have a fixed resistor or a variable one which is just like using a valve.

A diode can be compared to a check valve (non return valve) in a water circuit.

The diameter and also the length of a pipe have a bearing on the amount of resistance to the flow of water. But thats not so much of an issue in a computer case other than the cabling and any pins being of sufficient diameter to carry the current.

I hope you don't mind me giving my two bobs worth and if you can use any of it you may be able to word it better than I have, also you may not want to go into this sort of explanation thats ok too.

Thanks Sandman

That is an analogy I have heard many times. Now I would like your input as well as others' as to whether the intro is too wordy or complex for less experienced. I have a tendency to expect people to understand things I understand which is why I talk geek more often than I should.

Oh BTW: I actually don't know what a check valve is.

But I do know what a diode is of course.

**mattlock** · 09-30-2007, 05:20 PM

A check valve is design to prevent backflow.

JohnthePilot · 09-30-2007, 05:29 PM

Just think of it as a non-return valve Matt, which is basically what a diode is.

**TheMatt** · 09-30-2007, 05:30 PM

Now I get it.

09-29-2007, 03:51 PM	#21 (permalink)
TheMatt Moderator, Hardware Team Join Date: May 2006 Location: Boston Posts: 13,693 OS: Win 3.1, 98, NT 4.0, XP Debian 4.0, Kubuntu 6.06 My System Blog Entries: 3	Re: Testing Your Power Supply With a Multimeter Added testing AC outlets. I will need help with the wording on distinguishing the power holes on the outlet from the ground hole. Also, I have decided to divide the testing section up into these sections: Testing AC voltage from the wall Testing the power cord for resistance Testing +3.3v/+5v rails from the PSU Testing the various +12v rails from the PSU Testing the Power_Good signal from the PSU Testing the Power Switch for resistance __________________ - Matt M - KB1OSC - Folding@Home 85015 If TSF has helped you, please consider donating. If I have stopped responding to a thread, feel free to send me a PM with a link to the thread. It is advisable to subscribe to threads so you will receive updates when replies are posted. You can subscribe to threads from the "Thread Tools" Menu. »Memtest86 »Prime95 »UBCD »SpeedFan »NHC Personal »Everest »Sandra »PC Wizard »RivaTuner »ATi Tool Click here for Useful Articles and Guides

09-29-2007, 04:30 PM	#22 (permalink)
mattlock moderator hardware team Join Date: Dec 2005 Location: Ohio Posts: 3,803 OS: XP SP2, Ubuntu Gutsy Gibbon My System	Re: Testing Your Power Supply With a Multimeter Matt, nice article so far. On standard grounded outlets in the US, if wired properly, the hot side of the circuit is the shorter slot and neutral (or grounded side) of the circuit is the longer slot. You may want to add how to test if the outlet is properly grounded and polarized correctly. This is simple test. Insert the black probe into the round ground port and the red probe into the short slot. If you the reading is 115v then the outlet is grounded and polarized correctly. Although, since this is an international website maybe you shouldn't include this info, since electrical outlet configurations vary widely throughout the world. __________________ Matt Everest-Thermal Paste Instruction-Power Supply Info-Sensorview PSU Calculator-Speedfan-Bench Test Help TSF Fight Disease. It's Free!

09-29-2007, 05:02 PM	#23 (permalink)
TheMatt Moderator, Hardware Team Join Date: May 2006 Location: Boston Posts: 13,693 OS: Win 3.1, 98, NT 4.0, XP Debian 4.0, Kubuntu 6.06 My System Blog Entries: 3	Re: Testing Your Power Supply With a Multimeter Matt - don't you usually insert it into the ground to test voltage, you use the hot and cold holes. __________________ - Matt M - KB1OSC - Folding@Home 85015 If TSF has helped you, please consider donating. If I have stopped responding to a thread, feel free to send me a PM with a link to the thread. It is advisable to subscribe to threads so you will receive updates when replies are posted. You can subscribe to threads from the "Thread Tools" Menu. »Memtest86 »Prime95 »UBCD »SpeedFan »NHC Personal »Everest »Sandra »PC Wizard »RivaTuner »ATi Tool Click here for Useful Articles and Guides

09-29-2007, 05:47 PM	#24 (permalink)
mattlock moderator hardware team Join Date: Dec 2005 Location: Ohio Posts: 3,803 OS: XP SP2, Ubuntu Gutsy Gibbon My System	Re: Testing Your Power Supply With a Multimeter Yes. Going across the hot and ground well give you the voltage reading, just as if you were going hot to neutral. The neutral and gruond are connect at the main panel. To test if the outlet is properly wired, you would perform the test as listed in my post. Anytime I'm testing an outlet, I go across all three, hot to ground and then hot to neutral for voltage, then ground to neutral for continuity. The shorter slot of the outlet is supposed to be the hot side of the circuit. The longer slot is the neutral. If you go ground to the short slot and get a reading then outlet is wired and grounded properly. If you get no reading between the ground and the short slot but get a reading between the ground and longer slot the outlet is ground but not polarized properly. This test isn't that important in relationship to testing the PSU however, it's just some added info for piece of mind. Alot of homeowners simply install the pronged outlet so they don't have to use adapters but don't actually ground the outlet. Again, this info may not be relevant to your article, but thought I would throw it out there anyway. __________________ Matt Everest-Thermal Paste Instruction-Power Supply Info-Sensorview PSU Calculator-Speedfan-Bench Test Help TSF Fight Disease. It's Free! Last edited by mattlock : 09-29-2007 at 05:50 PM.

09-30-2007, 01:16 AM	#25 (permalink)
sandman55 TSF Enthusiast Join Date: May 2005 Location: Australia Posts: 3,809 OS: WinXP Pro SP2	Re: Testing Your Power Supply With a Multimeter Hi Matt thats a very good tutorial As an Electrician can I tell you the way electricity was explained to me and I have passed this on to apprentices under me. A lot of people become confused with voltage and amperage and they cant see it. I tell them to think of electricity the way you would think of water going through pipes. As the water pressure is the force pushing the water through the pipes example increase the pressure and you will push more water through the pipe. Likewise the Voltage (EMF electromotive force) is the pushing force that pushes the current through the wires. Increase the voltage and you will push more current through the circuit. Electrical resistance can be compared to partly closing a valve in the water circuit and that controls the amount of water that will flow. Likewise the resistor in an electrical circuit controls the amount of current flowing for a given voltage. You can have a fixed resistor or a variable one which is just like using a valve. A diode can be compared to a check valve (non return valve) in a water circuit. The diameter and also the length of a pipe have a bearing on the amount of resistance to the flow of water. But thats not so much of an issue in a computer case other than the cabling and any pins being of sufficient diameter to carry the current. I hope you don't mind me giving my two bobs worth and if you can use any of it you may be able to word it better than I have, also you may not want to go into this sort of explanation thats ok too.

09-30-2007, 02:59 AM	#26 (permalink)
JohnthePilot Asst Manager, TSF Articles Join Date: Mar 2006 Location: Cheltenham, near Wales. Posts: 26,729 OS: XP Home SP3, PCLinux, Vista Home Premium SP1 My System Blog Entries: 1	Re: Testing Your Power Supply With a Multimeter That's the analogy I was given as well. __________________ Submit New Articles Here If you feel that TSF has helped you please make a donationand help to keep the forum free Cenedl heb iaith, cenedl heb galon Folding@Home - Team 85015

09-30-2007, 03:38 AM	#27 (permalink)
sandman55 TSF Enthusiast Join Date: May 2005 Location: Australia Posts: 3,809 OS: WinXP Pro SP2	Re: Testing Your Power Supply With a Multimeter Great minds think alike I won't say the second half of the quote

09-30-2007, 05:20 PM	#30 (permalink)
mattlock moderator hardware team Join Date: Dec 2005 Location: Ohio Posts: 3,803 OS: XP SP2, Ubuntu Gutsy Gibbon My System	Re: Testing Your Power Supply With a Multimeter A check valve is design to prevent backflow. __________________ Matt Everest-Thermal Paste Instruction-Power Supply Info-Sensorview PSU Calculator-Speedfan-Bench Test Help TSF Fight Disease. It's Free!

09-30-2007, 05:29 PM	#31 (permalink)
JohnthePilot Asst Manager, TSF Articles Join Date: Mar 2006 Location: Cheltenham, near Wales. Posts: 26,729 OS: XP Home SP3, PCLinux, Vista Home Premium SP1 My System Blog Entries: 1	Re: Testing Your Power Supply With a Multimeter Just think of it as a non-return valve Matt, which is basically what a diode is. __________________ Submit New Articles Here If you feel that TSF has helped you please make a donationand help to keep the forum free Cenedl heb iaith, cenedl heb galon Folding@Home - Team 85015

09-30-2007, 05:30 PM	#32 (permalink)
TheMatt Moderator, Hardware Team Join Date: May 2006 Location: Boston Posts: 13,693 OS: Win 3.1, 98, NT 4.0, XP Debian 4.0, Kubuntu 6.06 My System Blog Entries: 3	Re: Testing Your Power Supply With a Multimeter Now I get it. __________________ - Matt M - KB1OSC - Folding@Home 85015 If TSF has helped you, please consider donating. If I have stopped responding to a thread, feel free to send me a PM with a link to the thread. It is advisable to subscribe to threads so you will receive updates when replies are posted. You can subscribe to threads from the "Thread Tools" Menu. »Memtest86 »Prime95 »UBCD »SpeedFan »NHC Personal »Everest »Sandra »PC Wizard »RivaTuner »ATi Tool Click here for Useful Articles and Guides

09-30-2007, 05:33 PM	#33 (permalink)
JohnthePilot Asst Manager, TSF Articles Join Date: Mar 2006 Location: Cheltenham, near Wales. Posts: 26,729 OS: XP Home SP3, PCLinux, Vista Home Premium SP1 My System Blog Entries: 1