Skip to content

Troubleshoot three common PC problems with a multimeter

  • by

When confronted with a desktop which will not power on, a multimeter could be the ideal instrument for troubleshooting. Learn how to effectively and safely use a multimeter to check an undesirable cable, faulty switch, or maybe smashed energy supply.

Whenever a computer will not power on, you will find a lot of possible reasons, like a terrible cable, faulty switch, or perhaps blown power cord. The best multimeters for computer repair are able to help you find the root cause of your specific problem easily and quickly. With this particular device, you are able to do continuity tests on switches and wires and evaluate the voltage on the power cord.

Follow vendor instructions carefully Remember that dealing with electricity can be really dangerous. The instructions of mine are supposed to as basic guidelines. Every multimeter is different, of course, if the user manual for the unique multimeter of yours varies from virtually any of the pointers of mine, you must stick to the manufacturer’s recommendations. Utilizing a multimeter improperly can damage your multimeter or PC and will result in death or injury.

Continuity tests As I describe in a prior post, a continuity test is an exam of circuit integrity to decide whether a circuit is done between 2 points. When working with a desktop, the most typical continuity assessments include testing cables and tests switches. Keep in mind that the PC must be disconnected from the energy source (not only turned off) prior to performing some sort of continuity test.

To test a cable In order to do a continuity test on a cable, established the multimeter to check probably the lowest possible amount of ohms and also work the way of yours up. Whenever the probes are shut off from the cable, the multimeter will show infinite resistance. On an analog meter, the tip is going to remain on the peg at the left end of the machine. There’ll usually be an infinity sign only at that conclusion of the scale. (On a digital multimeter, infinite resistance is suggested by the numeral one without using a decimal.)

Attach the probes to matching wires inside a cable, moreover the opposition will drop to near zero in case the cable is great.

To test a far more complicated cable, like a drive ribbon, works on the very same idea. You will continue to connect one probe to each end of the cable. The sole strategy is finding out what ports on the cable finishes share a typical wire.

To test a switch Another common use for just a continuity test is testing a switch. Usually, this’s used when evaluating the PC’s on/off switch. If the PC utilizes an ATX power source (which almost all more modern PCs do), the energy supply will keep the motherboard powered even once the PC is switched off. The power button was created so that the circuit is just connected as the button is held to. This’s viewed as a momentary. The basic act of pressing the button trips a logic circuit which starts the capability cycling process.

There’s no regular type of ATX switch. Some switches use 2 wires and some use 4 wires. In a two wire version, you are able to link the multimeter’s probes to the 2 wires (with the PC unplugged) and press the button in to view for a decline in resistance. In case the opposition drops to near zero, the switch is great.

The four wire switch is split into right side and the left. Often wires on the left go well as well as the wires on the proper go well; however, these’re often crossed. Make sure you test all combinations to check out for unintended present paths. When evaluating the switch type, unplug the PC and evaluate the 2 wires on the left followed by the 2 wires on the proper. Just like the two wire switch, the switch is going to show infinite resistance until you press the button in. If the switch is pressed in, the opposition must drop to near zero.

Voltage assessments Probably the most common troubleshooting task that you utilize a multimeter is usually to troubleshoot a power cord. An ATX power supply changes a 120 volt AC power supply into 12 volt, 5 volt, and 3.3 volt DC voltages. Various areas of the method board need different voltages. An ATX power supply continuously supplies a little amount of strength on the system board. Except if the power cord is adequately connected to the system board, the lover will not spin as well as the power cord will seem to be old.

A typical test for a power cord is checking the peripheral connectors, that are used to provide power to hard CD-ROM and drives drives. These connectors have 8 wires arranged into 4 pairs. From left to right, the cables are colored yellow, black, black, and white. In case you connect the multimeter’s red probe on the white cable as well as the black colored probe on the black colored wire that is alongside the red cable, it ought to read +5 volts DC.

Do exactly the same test by putting the multimeter’s red probe on the yellow wire as well as the black colored probe on the black wire that is alongside the yellow wire. This particular test must generate a reading of +12 volts DC.

If whichever measurement is off by a single volt or maybe more, you’ve either a terrible power cord or even way too many peripherals connected. Try disconnecting each peripherals and saying the test to determine if the voltage levels of yours are normal. When the voltage levels go back to normal, use fewer peripherals or even getting a greater wattage power cord. When the voltage levels continue to be very small with every thing disconnected from the power cord, it is time for a brand new power cord.