- Troubleshooting Motherboards
- Troubleshooting CPUs
- Troubleshooting RAM
- Troubleshooting Power Supply Issues
- Heating and Cooling
- Cram Quiz
- Cram Quiz Answers
This chapter is from the book
This chapter is from the book
This chapter is from the book
Troubleshooting Power Supply Issues
Many types of power problems can happen. We discuss power in general in Chapter 18, “Power,” and Chapter 60, “Environmental Controls,” but for now let’s focus on power issues related to the power supply within a computer.
Many issues that occur with power supplies are intermittent. This makes the troubleshooting process a little tougher. Your best friends when troubleshooting power supplies are a power supply tester and your eyes and ears.
Of course, always make sure that the power supply cable connects from the power supply to a properly wired AC outlet before troubleshooting further. Next, check all of the internal power connections. Make sure they are connected firmly. To test these connections, use a power supply tester.
A power supply tester (or PSU tester) is a tool every computer tech should have in their toolkit. Figure 23.1 shows an example of a PSU tester. These testing devices normally test for 12 V, 5 V, and 3.3 V for most of the connections within the computer, including the main 24-pin ATX power connector, 8- and 4-pin CPU connectors, PCI Express 8-pin and 6-pin connectors, SATA power connector, and Molex power connector. If there are error readings, error lights, no lights, or missing lights for specific voltages on the tester, you should consider replacing the power supply; or if it is modular, you should replace that particular power cable. If all the lights and indicators are normal, then the issue resides somewhere else.
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FIGURE 23.1 PSU Tester Testing a 24-Pin ATX Power Connector
Here are several of the issues you might encounter with power supplies:
Fan failure
Fuse failure
Quick death
Slow death
Fan failure can be due to the fact that the power supply is old, the fan is extremely clogged with dirt, or the fan is of a cheaper design (without ball bearings). However, for the A+ exam, the reason doesn’t make a difference. As far as the A+ exam is concerned, if the fan fails, the power supply needs to be replaced (and that strategy makes sense). Chances are, if the fan has failed, other components of the power supply are on their way out also. It is more cost-effective to a company to simply replace the power supply than to have a technician spend time opening it and trying to repair it. More importantly, although it is possible to remove and replace the fan by opening the power supply, this can be a dangerous venture because the power supply holds an electric charge. So, the A+ rule is to never open the power supply.
Fan failure can sometimes cause a loud noise to emanate from the power supply; it might even sound as though the noise is coming from inside the computer. Any fan in the computer (power supply fan, case fan, or CPU fan) can make unusual noises over time. If a customer reports a loud noise coming from the inside of a PC, consider the power supply fan as a suspect.
On the other hand, sometimes the fans spin but no other devices receive power, and the computer doesn’t boot. This could be due to improper installation (or failure) of the motherboard, CPU, or RAM.
Fuse failure can occur due to an overload or due to the power supply malfunctioning. Either way, the proper course of action is to replace the power supply. Do not attempt to replace the fuse. If the fuse is blown, chances are that the power supply is faulty.
If the power supply dies a quick death and provides no power, the reason might be several issues, ranging from an electrical spike to hardware malfunction. First, make sure that the IEC power cable is connected properly to the power supply and to the AC outlet. Sometimes it can be difficult to tell whether the power supply has failed or whether the problem is something else inside or outside the computer system. You should check the AC outlet with your trusty receptacle tester, make sure that a circuit hasn’t tripped, and verify that any surge protectors and/or UPS devices work properly. Depending on what you sense about the problem, you might decide to just swap out the power supply with a known good one.
A power supply that is dying a slow death may cause intermittent errors or frequent failure of hard drives and other devices, and this can be tough to troubleshoot. If you suspect intermittent issues, first make sure the power cord is connected securely and then try swapping out the power supply with a known good one. Boot the computer and watch it for a while to see if the same errors continue to occur.
Remember that connections sometimes can be jarred loose inside and outside a computer. Check the IEC cord on both ends and all power connections inside the computer, including the main motherboard connector as well as the CPU, Molex, SATA, and PCIe connectors. Any single loose connector can have “interesting” results on the computer!
