Complicatedness Firing Power Supply5520641

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Testing the motherboard power

Depending on whether you have an AT or an ATX motherboard, you?ll either have one or two connectors that attach the power supply to the motherboard. Whichever type you have, you should unplug the system from the electrical outlet before testing the motherboard power.

If you?re using an AT power supply, you?ll have two connectors, called P8 and P9, that connect the power supply to the system board. Detach the P8 and P9 connectors from the system board but make sure to note their positioning. Although both connectors are keyed to prevent you from putting them on backwards, it is possible to accidentally reverse the two connectors. Reversing the connectors will almost certainly destroy the motherboard and will likely destroy the power supply, too. When replacing the P8 and P9 connectors back on the motherboard, remember that the two black ground wires should be next to each other Both the AT and ATX power supplies supply power to the system board at the 12-volt, 5-volt, and 3.3-volt levels. The reason for the different volt levels is that various system-board components require different amounts of electricity.

Using your multimeter on an ATX power supply, pin 9 should have 5 VDC (Volts of DC power) flowing through it anytime the PC is plugged in. This should be the case whether the main power switch is turned on or off. You will notice pin 9 easily because it is typically a purple wire. Checking for a 5-volt DC on pin 9 using the multimeter is a good way to begin testing to see if the system board is receiving any power.

Once you?ve tested pin 9, test the voltage on the various 12-VDC circuits. You might have noticed that there are several black and several yellow wires on the P1 connector. The yellow wires indicate 12-VDC circuits. To test these circuits, set your multimeter to the 15-VDC or 20-VDC range (depending on what your individual multimeter uses). Next, with the PC powered on, place the red probe onto a yellow wire on the P1 connector and then place the black probe onto a black wire. Because the PC must be powered on, the P1 connector must be connected to the system board.

Once the probes are connected, your millimeter should indicate a voltage between 11 and 13 VDC. If a power supply is slowly dying and causing the types of problems that I described earlier, the voltage will be a little below this level. If you read a power level between 10.5 and 11 VDC, then your PC needs a new power supply. If you read anything below 10.5 VDC, there?s a good chance that your PC won?t boot until you replace the power supply. You may also notice voltage drops on the 5-VDC and 3.3-VDC circuits, but these voltage drops are smaller because you?re dealing with less power to begin with. Therefore, I recommend performing the tests on the 12-VDC circuits. Conclusion

A faulty power supply is not the easiest PC component to detect, and it is often overlooked when troubleshooting in favor of the more popular PC hardware problems most IT pros check first. However, armed with a multimeter, you can quickly check the connections for proper current flow. The heart of most power supply problems exist at the power input and motherboard, so by testing these areas as I've described above, you should now be able to rule out the power supply as the culprit.

Know more about: 48 VDC Power supply

Complicatedness Firing Power Supply5520641

De BISAWiki

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