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Using A Multimeter| Category | | | Summary | | Ever wanted to find out how to muse a Multimeter? Click 'Read More' to find out. |
| | Body | On a computer, a multimeter is used to measure voltage (volts) and resistance (ohms) between two points. Volts and ohms are always measured between two points. Typically, current (amps) is not measured on a computer because the circuit must be altered to do so. If you really need to know the amps of a circuit, it's easier to measure the volts and amps and then calculate the amps using Ohm's law (a = b/c), where a is the amps (current), b is the volts, and c is the ohms.
You can make four different measurements on a computer using a multimeter:
1. Amps: Measures strength of an electrical current.
2. Farads: Measures the capacitance of an electrical device.
3. Ohms: Measures the resistance in an electrical medium.
4. Voltage: Measures the electrical potential of a circuit.
When preparing to use a multimeter, you need to set three things:
1. The type of current you're measuring: AC or DC.
2. What you're measuring: Set the appropriate indicator or dial to voltage, current, or resistance or continuity.
3. The range of values expected: If you're measuring voltage from the power supply, the voltage range is 3V to 12V, and for the AC wall plug's output, the range is around 105V to 125V.
Measuring Volts
Voltage is the easiest measurement. Here are some general steps:
1. Set the dial to measure DC voltage.
2. Choose the voltage range. Usually 20V or lower.
3. Hold the black probe to a grounding point.
4. Touch the red probe to a hot point.
That should keep you from killing yourself.
Measuring Volts on a Power Supply Connector
1. Turn off the computer, but leave it plugged in.
2. Turn on the multimeter and set it to measure DC current voltages less than 20V.
3. Open the case and remove cover.
4. Locate an unused power supply connector or remove one from a disk drive.
5. Turn on the computer.
6. Touch the black probe to one of the black wires on the power controller.
7. While holding the black probe on the black wire, touch the red probe to the connector's yellow wire. You should see a reading between 11.5V to 12.5V. If you get something around 5V you probably have the probes reversed.
8. Touch the red probe to the power connector's red wire while still holding the black probe to the black wire. You should now have a reading between 4.8V and 5.2V.
For most computer repair technicians, a multimeter is a very useful tool. You can find a good multimeter at Radio Shack or some other electronics store for around $20 USD. You really don't need to pay any more than that for one. |
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This article was imported from zZine. (original author: biggytek)
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