Power supply troubleshooting pdf

The power supply is the most important component in a desktop PC. It is responsible for providing constant and stable power to the motherboard, processor, video, storage devices and every other component in the system. A bad or poor power supply can cause numerous problems for a PC. A bad power supply can cause lockups, reboots, and generate excessive heat, not to mention shortening the life span of other components. An under powered power supply can also limit system expansion.

Sometimes the problem may appear to be from a different component when in fact it is the power supply. Another example of misdirection in troubleshooting is a memory error.

If a parity check message appears frequently, but not at the same memory location, or is described as random by the end-user, then suspect a power problem. American Power Conversion has spent millions of dollars advertising the importance of power.

Ironically, the power supply is rarely discussed in technical publications and books. In fact, out of 13 computer books offered for sale in a local Barnes and Noble, only two devoted more than a paragraph or two to the topic of power. The picture and text discuss the AT power supply, and in fact, the book devotes two pages to installing and troubleshooting the AT power supply.

With such a dichotomy between the importance of the power supply and publications, it is no wonder that technicians rarely look toward the power supply as a cause for problems. Can you email TheKanter and he can let you know? Registration is strictly optional.The PC power supply is probably the most failure-prone item in a personal computer. It heats and cools each time it is used and receives the first in-rush of AC current when the PC is switched on.

Typically, a stalled cooling fan is a predictor of a power supply failure due to subsequent overheated components. All devices in a PC receive their DC power via the power supply. A typical failure of a PC power supply is often noticed as a burning smell just before the computer shuts down. Another problem could be the failure of the vital cooling fan, which allows components in the power supply to overheat.

Failure symptoms include random rebooting or failure in Windows for no apparent reason. For any problems you suspect to be the fault of the power supply, use the documentation that came with your computer. If you have ever removed the case from your personal computer to add an adapter card or memoryyou can change a power supply.

Make sure you remove the power cord firstsince voltages are present even though your computer is off. Prev NEXT. Power Supply Problems.Home Troubleshooting. Dolphin Download PDF. Download PDF. Download Quick Start Guide.

power supply troubleshooting pdf

Alternative power supply types. If the suggest solutions do not solve the problem contact your dealer Problem Solution Pool Cleaner does not move Check that the power supply cable is plugged properly into the power supply socket. Check power to the socket and reconnect Pool Cleaner Ensure the power outlet is functioning properly and that it has not tripped the breaker in the fuse box Turn the power supply off.

Wait 30 seconds then turn it back on Unplug the power supply. Open the impeller cover and check that nothing is trapped in the impeller The Pool Cleaner moves but does not clean the pool Clean the filters of the cartridges After the Pool Cleaner starts moving observe it for several minutes and make sure that it keeps moving.

power supply troubleshooting pdf

Improper levels may allow the growth of algae making the walls slippery. Full Manual.

power supply troubleshooting pdf

Quick start guide. Warranty registration. Customer care Contact customer support Find a distributor. Check that the power supply cable is plugged properly into the power supply socket. Open the impeller cover and check that nothing is trapped in the impeller. The Pool Cleaner moves but does not clean the pool. Clean the filters of the cartridges After the Pool Cleaner starts moving observe it for several minutes and make sure that it keeps moving.

If it stops moving check the impeller and the drive system to see if any debris is stuck there. The Pool Cleaner floats instead of sitting on the floor of the pool. To remove the kinks stretch the cable out completely and let it sit for at least a day in the sun push in the float on the non-cable side see figure B.Modern power supplies are known as "switching regulator power supplies. This creates two high- voltage sources; one positive and the other negative. A pair of transistors is then used to switch these high voltage supplies across the primary winding of a transformer.

This switching action is very fast. A typical switching speed is around 40, cycles per second or 40KHz. An integrated circuit is commonly used to control the transistors.

This IC not only controls the speed at which the transistors are switched, but also controls the amount of time that each transistor is energized. The output voltage of the power supply is determined by the "on" time of the transistors. If the transistors are keep on for a longer period of time, the output voltage of the supply will rise, while shorter times lower the output voltage.

This is known as "pulse-width modulation. All Rights Reserved. ATX power supply interior Legend: A - bridge rectifier B - input filter capacitors between B and C - Heatsink of high-voltage transistors C - transformer between C and D - Heatsink of low-voltage, high-current rectifiers D - output filter coil E - output filter capacitors The output of the transformer which is now alternating current is then rectified by special high-speed diodes to change it back to direct current.

This output is not pure DC however, and requires extensive filtering to remove the high-frequency "noise" that is generated by the rapid switching action of the transistors.

Filtering is accomplished by using a combination of coils also known as "chokes" and capacitors. The output voltage of the power supply is regulated by feeding some of the output back to the integrated circuit that controls the switching transistors.

If the output voltage is too low, the IC allows the transistors to remain energized for a longer period of time, raising the voltage. An output voltage that is too high signals the IC to cut back on the transistors, lowering the output voltage. Power Supply Failures I have found that there are only a small handful of components that fail in switching regulator power supplies. The most common failure is the switching transistors themselves.

The transistors short-circuit, causing massive amounts of current to be drawn across the transformer and blowing the fuse. Transistor failure is often caused by bad capacitors. It is extremely common to find output filter capacitors that are swollen or leaking.

Any capacitor that appears to be bad should be replaced. To prevent a recurrence of this all-to-common failure, output filter capacitors should be replaced with special "low ESR" Equivalent Series Resistance capacitors.

These capacitors are specifically designed to handle the rigors of filtering in a switching supply. Most power supply manufacturers do not install low ESR capacitors as original equipment because they are somewhat more expensive that conventional capacitors. However, it is well worth the money to use them as replacement components as they will greatly extend the life of the power supply in the field.

When I work on a power supply, I replace all the output filter capacitors with low ESR caps regardless of whether they appear to be good or bad. Since a service call costs far more than the capacitors, it's a prudent thing to do. Diode failure is another common problem. There are quite a few diodes in a switching supply and failure of any one of them will cause the supply to blow the fuse or shut down.

Failure of these diodes will not blow the fuse. The supply simply detects the short and shuts itself down. The -5 volt output is not over- current protected in all power supplies. A shorted lamp socket may blow the diode by drawing too much current from the supply.During these challenging times, we guarantee we will work tirelessly to support you.

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Thank you to our community and to all of our readers who are working to aid others in this time of crisis, and to all of those who are making personal sacrifices for the good of their communities. We will get through this together. When a PC power supply dies or begins to wear out, it must be replaced. With a few simple tools and the help of this guide, you can do this job yourself and save on expensive repair fees. Log in Facebook Loading Google Loading Civic Loading No account yet?

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Power Supply Troubleshooting and Repair Tips

Method 1 of Make sure that everything is plugged in. It's entirely possible that a cord could just slip out from the outlet while you're working. If power is present to the monitor and other peripherals, yet there is no power to your computer, there is likely something wrong with your power supply. Hit the power button.


The most obvious clue is that the system will do absolutely nothing when you hit the power button. If there is no sound and no monitor activity of any kind, the power supply has probably died. While this can also be caused by a faulty switch, it is usually the result of a burned-out power supply.You must unplug your ATX power supply from the wall before working inside the case.

The power supply troubleshooting chapter below is from my book, "Computer Repair with Diagnostic Flowcharts, Third Edition. ATX Power Supply Failure Diagnostics Note that these steps correspond with decision points on the flowchart and are reached directly by clicking on the diamond symbols.

The text below cannot be read sequentially. The first step in the troubleshooting process is simply determining if the power supply is coming on.

You can usually hear the mechanical components in PCs that make rotational noise when they are powered up. Noise makers include the hard drive, as its electric motor spins up the platters, and plenty of fan noise is normal for PCs without PWM Pulse Width Modulation fans.

Your PC should also give a single beep if it passes its internal start-up diagnostic, and there are always status LED's to tell you the system is on, though some home PC builders don't bother connecting them. If your hearing isn't good, you can check to see if the power supply fan is creating a breeze.

Monitors are powered independently, so unless you're looking at a notebook PC, a live screen doesn't indicate a working power supply. Return to Diagnostic Chart If your computer has a display connected, can you get a live screen, whether it's a simple text message or a colorful splash screen?

If the display shows a message like "No video signal detected," that's the monitor telling you the video port isn't communicating, so you should follow the "No" path for this decision.

Sometimes a CRT or older LCD may show a multiplicity of images or endless scrolling, which means the video adapter is alive and trying to transmit an image but the monitor can't interpret the signals.

This doesn't happen as often with modern LCDs or expensive CRTs that can match a large range of inputs for higher screen resolutions set in Windows. If you are using a high definition TV for your primary display, do yourself a favor and use a standard monitor for troubleshooting until you eliminate the power supply as an issue.

The primary culprits are multi-core CPUs that can consume anywhere from 10W to 50W or more per core, for a total CPU consumption as high as W in a single processor system. Meanwhile, PCI Express graphics cards for gaming can pull as much as Watts by themselves, or double that in a dual card configuration.

While PC power supply manufacturers boast about their power rating since it's their main selling point, manufacturers of video cards and other components don't trumpet their power consumption. You may have to do a little math to work it out.

Sometimes they give the peak current requirement in Amps A at the supply voltage, usually 12V, so you multiply the two numbers for the power consumption in Watts. All of the high end video cards require more power than can be supplied through the PCI Express slot on the motherboard, so they are fed directly from the power supply with one or two 6-pin PCI Express supplementary connectors.

Older video adapters employed the 4-pin Molex drive connectors. A quick search online will help you find a number of calculators for determining your power supply requirement based on the components installed. If the power supply boasts of a peak power rating, don't use that as your guide. Peak power is not sustainable, it's only a meaningful metric for electrical devices with transient demands, like electric car motors that can safely exceed their maximum power rating for short periods during acceleration.

Return to Diagnostic Chart If the power comes on but the screen never goes live, try switching back off again and retrying.In the case of the power supply example illustrated in Figure bthe symptom is that the output voltage is not a constant regulated dc voltage.

Understanding and Troubleshooting the PC Power Supply

Something as simple as this is sometimes the cause of a problem. However, in this case, there must be power because there is an output voltage. Beyond the power check, use your senses to detect obvious defects, such as a burned resistor,broken wire, loose connection, or an open fuse. In this phase, you must consider how you will attack the problem. Therefore, begin tracing the voltage from the test point toward the input.

An open filter capacitor is indicated. Fig b : Measurements starting at the regulator output. Save my name, email, and website in this browser for the next time I comment. This website uses cookies to improve your experience.

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