How to repair laptop power problems
This article is only for the experienced people who know
well, how to assemble and disassemble laptops.I will explain the basic troubleshooting of the motherboard.Because laptops are designed to be portable and function on battery power, they are engineered to run on the DC (Direct Current) power that batteries provide. But all of the power distribution networks in the modern world utilize AC (Alternating Current) because it’s a more efficient and economical way to move electricity long distances.
This means that laptops are shipped with an AC adapter that plugs into a regular outlet and converts that AC power into the proper DC voltage for the laptop. Most modern AC adapters for laptops can function on a power grid ranging from 100 to 240 volts AC. You should take a look at the label on the AC adapter, often called a “brick” before you go traveling around the world. All that’s needed to plug a variable AC adapter into a different power grid is a new end for the plug, purchased at a local hardware store for around a dollar.If your laptop doesn’t turn on when you hit the power button, the power system is a logical place to begin the troubleshooting process. The laptop power system can be viewed as three separate parts: The A/C adapter that gets plugged into a power outlet on one end and into the laptop on the other end, the laptop motherboard or power regulation daughter card that monitors and distributes power to the laptop components, and the battery.
The vast majority of laptops manufactured these days can operate without the battery installed. In some cases, the manufacturers will suggest that you remove the battery and store it somewhere cool if using the laptop in one location for extended periods of time, as in weeks or months. In all instances, it pays to read the owner’s manual on how to best extend the battery life for the particular model.One of the oddities about troubleshooting laptop power failure as opposed to PC power failure is that the battery gives the laptop an independent power system for as long as the charge lasts. If the PC in your home is plugged into a bad power outlet or its power strip is accidentally switched off you’ll quickly figure out why. But if the power strip gets turned off while you are operating your laptop, or a breaker trips, or the local power grid suffers a brown out, you might not even notice until the battery runs down. That’s why it’s important to not jump to conclusions about laptop battery failures, and to try charging the battery under different conditions before giving up and buying a new one.
Just because the battery didn’t charge while the laptop was plugged in doesn’t mean the battery is bad. The power to
the AC adapter may have been interrupted, the AC adapter or cable to the laptop may have failed, the connector tip may have been partially plugged into the laptop, or the battery may have become partially unseated. There could also be something wrong with the laptop charging circuitry or software. Running out and buying a new battery before investigating all the possibilities will often mean a $100 or $150 mistake.New laptops should have a status LED in a visible location on the front or keyboard surface of the laptop that tells you when the power input is good. However, that doesn’t help you determine where the failure is if the LED doesn’t light, or isn’t lit steadily. A simple DC voltage meter can be used to confirm that the AC adapter is putting out the correct voltage, though it will usually read a little high since there’s no load on the output. A harried technician may stick the DC connector on his tongue as a quick test to see if it’s live, but you can’t taste the difference between 12.5 volts and 18.5 volts, and you probably shouldn’t try. Another crude check is whether or not the AC adapter gets warm while it’s plugged into the laptop and a live power outlet. It shouldn’t get hot, just warm to the touch if the battery is charging or the laptop is operating.
Some AC adapters
are equipped with a status LED right on the brick that tells you when the AC adapter believes it’s functioning properly. Don’t forget to make sure that the cord from the wall outlet to the AC adapter is firmly plugged into the brick.Electronic devices often produce high frequency buzzes and whistles under regular operating conditions. Some people can hear these sounds, especially young folks and women, while
older men tend to have very limited high frequency hearing. A high frequency whistling sound may indicate a capacitor in the AC power adapter is beginning to fail, but it will often whistle while it works for years to come. You don’t have to replace the AC power adapter just because you can hear it, unless it gets worse and worse over time or it gives you a headache. Because AC adapters employ switching mode technology, they are more likely to make noise when the battery is fully charged and the laptop is turned off. AC adapter bricks are usually glued shut and aren’t designed for consumer repairs, so unless you have solid electronic troubleshooting skills and a source for parts, it’s a question of living with it or replacing it outright.
The real killer is when the connector inside the laptop
fails. Sometimes the center pin of the connector breaks off,
sometimes the solder joints on the main board fail, sometimes there’s a break between the connector contacts and the motherboard contacts. In all these instances, you or the technician has to gain clear access to the main board in the laptop to make the repair. Even with clear disassembly
instructions, it’s a big job to attempt on your own and requires decent soldering skills. It might be worth the effort if your only cost effective alternative is replacing the laptop outright. The replacement connector usually retails for less than $10 (and wholesales for pennies), but the repair charge can be several hundred dollars for some models if you take it to a local shop.Within the laptop itself, most components receive power by way of direct connection to the motherboard or through very short cables. In this way, laptops are less complicated than PCs, where the drives and some power hungry video cards are connected directly to the power supply by long cables with multiple connectors. Because of this, power failure to the hard drive or DVD player in your laptop is rare, and in most cases would be corrected by reseating the drive in the connector. But power failures can occur if the main board is damaged when the
laptop is dropped or a foreign substance (like beer) is introduced. However, the laptop screen, its supporting hardware and any special features such as a web cam incorporated in the lid, are powered by cables running through the laptop hinge. When troubleshooting possible power failure to the components in the laptop lid, you have to eliminate cable failure in the hinge or at the cable connectors as a cause.
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