Do I need a new power supply?

[westom]

This may be a dumb question.  But how could the voltages be measured just by
touching them when the wires are insulated?

Obviously touching insulation is not touching the wire. Every wire is
perfectly exposed where it enters the white nylon connector. Simply
push the probe into the back of that connector to be touching the
wire.

Black wire is connected to meter chassis. Clip or attach black
meter probe to the chassis or to the black wire in any unused four
wire, disk drive power connector. Touch with the red meter probe each
wire where it is obviously exposed and available in the nylon
connector. Read numbers (or response when switch is pressed). Report
that here.

Paul has suggested a similar solution.

 

[Frustrated]

Paul wrote:
:: To measure the voltage safely, do the following.
::
:: 1) You need a multimeter, two test leads, and at least one alligator
:: clip. You place the alligator clip on the black lead, then snap
:: the alligator clip onto an I/O screw on the I/O panel on the back
:: of the computer. This ensures you don't get the tips of the
:: probes too close together, and short out the power supply. The
:: chassis is grounded, and that is how you'll be picking up ground.

I have leads but no aligator clips.

:: 2) Now, using the red test lead, with the meter set to 20V full
:: scale or a higher range, you push the test lead tip, into the
:: back of the main ATX power connector, where the wire goes into
:: the plastic shell. There is enough metal exposed in each nylon
:: shell hole, for you to be able to take a reading.
::
:: (slide the tip of the probe, next to where the wire goes in, in the
:: right most picture here. The wires are crimped to metal pins, and
:: he metal will be accessible on each one.)
::
:: http://www.playtool.com/pages/psuconnectors/main20pin.jpg
::
:: I don't know what you're trying to measure, but that is how to do it.
:: You can do that with the computer running. Since you've only got one
:: test lead in your hand, it is pretty difficult to get yourself into
:: trouble. Just make sure the red and black test leads are in the
:: "voltage holes" on the multimeter, and not the "current holes".

Thanks for the pic. However, I'm still confused. I am trying to measure
the orange wires like westom has suggested.
I don't get how I am going to get a full load reading when I disconnect the
ATX power connector and then insert the lead into it.

 

[Frustrated]

westom wrote:

: Obviously touching insulation is not touching the wire. Every wire is
: perfectly exposed where it enters the white nylon connector. Simply
: push the probe into the back of that connector to be touching the
: wire.

Umm. What's the white nylon connector? Do you mean molex connector?
:
: Black wire is connected to meter chassis. Clip or attach black
: meter probe to the chassis or to the black wire in any unused four
: wire, disk drive power connector. Touch with the red meter probe each
: wire where it is obviously exposed and available in the nylon
: connector. Read numbers (or response when switch is pressed). Report
: that here.

What's a a meter chasis? Do you have any pics?

 

[Paul]

Paul wrote:
:: To measure the voltage safely, do the following.
::
:: 1) You need a multimeter, two test leads, and at least one alligator
:: clip. You place the alligator clip on the black lead, then snap
:: the alligator clip onto an I/O screw on the I/O panel on the back
:: of the computer. This ensures you don't get the tips of the
:: probes too close together, and short out the power supply. The
:: chassis is grounded, and that is how you'll be picking up ground.

I have leads but no aligator clips.

:: 2) Now, using the red test lead, with the meter set to 20V full
:: scale or a higher range, you push the test lead tip, into the
:: back of the main ATX power connector, where the wire goes into
:: the plastic shell. There is enough metal exposed in each nylon
:: shell hole, for you to be able to take a reading.
::
:: (slide the tip of the probe, next to where the wire goes in, in the
:: right most picture here. The wires are crimped to metal pins, and
:: he metal will be accessible on each one.)
::
:: http://www.playtool.com/pages/psuconnectors/main20pin.jpg
::
:: I don't know what you're trying to measure, but that is how to do it.
:: You can do that with the computer running. Since you've only got one
:: test lead in your hand, it is pretty difficult to get yourself into
:: trouble. Just make sure the red and black test leads are in the
:: "voltage holes" on the multimeter, and not the "current holes".

Thanks for the pic. However, I'm still confused. I am trying to measure
the orange wires like westom has suggested.
I don't get how I am going to get a full load reading when I disconnect the
ATX power connector and then insert the lead into it.

I guess I wasn't clear. Leave the ATX connector installed on the motherboard.
The computer can be running while you make a measurement, without a problem.
I've done this a few times, on my computers here.

When the connector is installed on the motherboard, you can see the white
nylon shell, and 20 wires coming up from it. Each wire goes into a square
hole. If you look down into that square hole, you can just barely see a
bit of exposed metal, from the pin which is crimped onto that wire. What
you want to do with your red multimeter test lead, is touch that metal
down in the hole.

Since there is a nice nylon square around each piece of metal, there
is no danger of a short circuit. Just stick the probe in the hole,
until you hit metal. Then your meter will show a reading. Make sure
the meter is set up to measure volts, and that you're using the holes
on the meter intended for voltage measurement.

If you don't have an alligator clip for your black test lead, find
some way to hold the test lead secure to some shiny conductive
grounded material on the computer. The reason I've suggested
this method, is to avoid you getting the two test leads close
together, as there is a danger you could short the tips together.
That is why I suggest placing the second test lead, out of
harm's way. Having to handle just the red test lead, is a lot
easier when making measurements.

Paul

 

[westom]

What's a a meter chasis? Do you have any pics?

That was a typo. It should have read "touch the black lead to
chassis". Connection can be held with anything - even duct tape or
scotch tape - as long as the probe touches unpainted metal.

Don't worry about touching only the right thing. Most anything
exposed can be touched with that red probe and not cause damage.
(Disconnecting, removing, or touching hardware with a finger (static
electricity) puts electronics at greater risk.)

Do same measurement for the purple, any red, and any yellow wire.
All are easily exposed inside the white (sometimes it is a Molex)
connector. Read numbers when the computer is multitasking to (all
peripherals - maximize the load).

If confused, get any battery. Touch battery contacts to both meter
leads. Read battery voltage (which also reports how 'good' that
battery is). Measuring any battery voltage is similar to what is read
on the orange, purple, red, and yellow wires.

 

[Mike Tomlinson]

What's a a meter chasis?

There is no such thing. Tom is talking out of his arse as usual. Just
put him in your killfile, his "advice" is a total waste of time.