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Laptop Troubleshooting Flowcharts
- Laptop Power Flowchart
- LCD Problem Flowchart
- Laptop Battery Charging
- Troubleshooting Laptop Overheating
- Wireless Internet Connections
- Laptop Hard Drive Failure
- Extending Laptop Battery Life
- Buying a Second Hand Laptop
- Upgrading a Notebook
- Your First Sale
- From Hobby to Self Employed
- Buying and selling hardware
- Selling Service
- Computer Franchises
- Accounting and Taxes
- Hiring Computer Techs
Copyright 2012 by Morris Rosenthal
All Rights Reserved
Laptop Won't Power On
Warning! Before Disassembling Laptop always unplug power and remove the battery.
When your laptop won't turn on with the AC power adapter plugged in, many people assume the adapter has failed and run out to buy a new one. That's an expensive way of troubleshooting a problem that you probably don't have. The flowchart and text below are from the collection of twelve flowcharts in The Laptop Repair Workbook which were specifically designed to help you troubleshoot laptop hardware problems before spending money on parts.
The diamond symbols are linked to text that explains each decision point.
Troubleshooting a AC/DC Adapter Problem and Laptop Power Connector
Note that these steps correspond with decision points on the flowchart and are reached through the interactive diamond symbols. The text below cannot be read sequentially.
Is the laptop power LED lit? Laptops typically feature a row of LED's on the front which report the status of different laptop systems.There's an LED that should light when the AC adapter is plugged in, an LED that should show when the battery is accepting a charge, and an LED that lights when the power is on. Most laptops also include LEDs to show hard drive activity and when the wireless is powered on. Some brands put a light right in the power button to show the unit is powered up. At this step of the troubleshooting process, we're looking for the LED that confirms the battery is charging or that a good power supply is connected. When the laptop isn't turned on, these should be the only two LEDs lit.
Does the LED wink if you wiggle the power cord? Once you've located the LED that monitors the status of the AC adapter or tells you whether or not the battery is getting charged, try wiggling the power cord. If the LED blinks on and off as you wiggle the cord, it means you have an intermittent short or open circuit, and the laptop isn't likely to get the power it need unless the cord is in just the right position and you don't breath on it. So the next step is to troubleshoot whether the problem is frayed conductors in the power cord, a broken solder joint or tab inside the laptop's power port. The common failure point for the cord is right where it enters the injection molded section that holds the metal connector tip. It's the injection molded part that you hold when pushing in or pulling out the connector. If moving the cord very slightly winks the LED, so slightly that there's little chance the movement is transmitted to the connector, then the problem is almost certainly a frayed wire right where it's molded into the connector.
Does the laptop beep multiple times? Laptop computers start up with a Power On Self Test (POST) procedure, just like PCs. The test is carried out by the Basic I/O System (BIOS) which is in sole control of the laptop until the operating system takes over high level operations. If a failure is detected during the POST test, it will normally be reported by the BIOS as a beep code. Make a note of the series of beeps, which will depend on the BIOS and the laptop manufacturer, and then use your favorite Internet search engine to search for your specific laptop model with the key phrase "beep codes."
Will the laptop boot if all external devices are unplugged? Sometimes a laptop will fail to boot because of a short circuit or atypical condition with a peripheral connected to the laptop. You should suspect everything, the printer, your big external LCD, and especially any USB devices that include memory and can be mistaken as bootable by the laptop. I believe that many years ago I saw a USB mouse keep a laptop from finishing the power on cycle. In any case, you can troubleshoot all external problems by simply disconnecting every external device from the laptop. If it turns out the problem was a memory stick, photo memory reader or external drive plugged into a USB port, check the CMOS settings and make sure the laptop hasn't been told to boot from a USB drive if there's one present.
Can you hear a cooling fan or the hard drive? Often times the the power supply section of the laptop is good, but the laptop still doesn't get very far into the boot sequence. The obvious signs of life, beyond the status LEDs, are what you can hear. The laptop hard drive can often be heard chuckling away if it's trying to boot, and even the best hard drive make a steady, quite droning when they are spinning. You should also hear the cooling fan come on, at least at the very start of boot, though it might quiet right down again. If the hard drive LED does blink merrily away for an extended period of time, there's a real good chance the laptop is booting but the display has failed. The easiest way to check is to connect an external LCD display. Sometime the laptop will fail to automatically detect the external display and you'll have to use a function key combination to switch the signal to the external port. The little symbols on the laptop keys along the top of the keyboard usually give you a decent guess, by showing two monitors on a key or something similar.
Does the laptop show momentary signs of life? There's a difference between a laptop that begins to power up in earnest and one that gives it a quick shot and shuts right off. If the hard drive starts and cuts right out again, or if the LEDs flash and go out, there's a good chance the laptop BIOS has decided that something is very wrong and shut itself down for self protection. Even a brief flicker on the LCD counts as a sign of life. Some laptops act this way if the battery is stone dead or is some cells have flipped for an unacceptable voltage. Try powering up without the battery installed unless the laptop manufacturer warns against it. It could also be the power circuit is failing it's own power-good stability test.
Can you feel switch action when you press the switch? Laptop power switches all have different feels, just like keyboards, but there should be some reaction that lets you know you are actually pressing a switch. If you don't feel much of anything, like the switch is merely a bit of plastic that's hinged on the side and hanging loose, there's a good chance that the problem is mechanical switch failure. It's not all that common of a problem, but it can be a big deal to replace the switch depending on how the laptop is put together.
Does redoing the internal connections fix the problem? The main difference between laptops and PCs when it comes to connector problems is that laptops get banged around a lot more. Thanks to travel in cars and airplanes, laptops experience all sorts of vibrations, and that in a piece of equipment that's often encased in plastic!. Engineers have been aware of these issues for nearly three decades now, so laptops are built with latching connectors, special adhesives, and all sorts of shock absorption to let them survive the beating. Still, it's not all that rare for a connector to fail or for a cable to work free. If you haven't taken apart your laptop before and don't have manufacturer instructions, your main resource will by YouTube videos. Do a search on your exact model to start, and if you can't find that, extend it to the basic model family. If you take the laptop apart, press or remake the connections, and everything is peaches when you reassemble, it was likely just a tired connection.
Is the DC voltage good at the output? The purpose of your AC/DC adapter is to create a stable DC voltage without too much ripple for charging your battery and operating your laptop. The DC output ratings depend on your model and are printed on the label of the transformer brick. You might see 16V at 3.5 A or 20V at 2.0A, it's a function of the battery voltage and the power circuitry of the laptop. Don't try using a different AC adapter just because the plug seems to fit. You want the proper voltage and an exact match on the connector so you don't break the power port. If you have access to a voltmeter, check the output DC voltage, but be very careful that you don't short across the end of the barrel connector when you go to probe the inside. Think it through first. You can't really get a good reading on a laptop battery with a meter because a battery will read a higher surface charge when there's no load pulling the voltage down. The voltage you read on the DC adapter should be within a few percent of the label specs, I'd be worried if it was five percent out.
Is the DC connector loose in laptop? There are two parts of the DC port on the laptop motherboard that can fail, and each can fail in two ways. The most common port type is a for a coaxial barrel connector, which requires a conductive pin to be centered in the power port. The pin can fail, literally breaking off, or the bit of metal that connects the pin to the motherboard can fail, often at the solder joint due to overheating. The main culprit for breaking ports is violence done to the cord while it's connected. If you get up and try walking away with the laptop only to find out the power is still connected when you run out of cord, that's a good way to break a connector. So is letting the cord dangle across a floor where people walk by and catch their feet. I've seen power ports where the pin broke off but remained in the connector, and they still worked (sort-of) if it was plugged in tight! In any case, if the center pin is still there but it moves easily if you touch it with something, it needs to be repaired.
The outer conductor, usually the ground contact for the outside of the barrel connector, can also fail, though it's a much less common problem than the center pin. So it's possible for the outer contact to break off or get bent too far out of the way by violence, but it's more common for it to fail at the motherboard solder joints. Replacing the power port on the laptop motherboard isn't much fun, primarily because getting the motherboard out of the laptop to do the job nicely means taking the whole thing apart. You should have a good quality soldering iron with a very fine tip if you want to try this. Figuring out the right connector to buy can be a challenge as well, I once gave up and just soldered the cord to the motherboard and put a connector on the cord, so there was always a tail hanging out of the laptop.
Is the internal power jack loose? I screwed up here when I drew the draft flowchart because I couldn't connect the two points I wanted. I changed it for the book, I'm not sure why I never updated the flowchart here. I was trying to differentiate between a total power failure and an intermittent power failure, and it didn't quite work. The flowchart in the book ended up with one more decision point overall, and no duplication.
Will the laptop power up with battery removed? Remove the battery and see if the laptop will start up. If the laptop starts without the battery, it could be the connector in the battery compartment or the battery itself. Look the battery over carefully, checking for signs of leaking, melting or swelling, and don't plug it back in if there's any evidence of failure. Check the connector that mates the battery to the laptop for looseness, staining or burn marks, bad alignment, signs of plastic melted on the contacts. Some old laptops wouldn't work without a battery installed, but those days are pretty much behind us. I frequently run my laptop for months at a time without the battery installed, and even when I travel, I find myself looking for power outlets in the airport to conserve battery life, so who needs it? If you need it, you can purchase replacement batteries for much cheaper than they used to be, I like Amazon for the selection of third party sellers. Just remember to check if there are any recall notices for your battery before you buy a new one, you could get a freebie.
Does the laptop power up when it's stripped down? I wouldn't advise you try this unless you're a reasonable hand at technician work or absolutely desperate. You can try powering up the laptop in various states of disassembly, though it could involve foiling safety mechanisms that are meant to prevent this, and for good reason. Removing the drives and trying to power up just to see if you can get a live screen is the easiest version, though the DVD drive can be a bear to remove on some models. It's not likely that taking the laptop apart and trying to power it up will get you any further than simply taking it apart, looking for signs of damage, and putting it back together if you don't find any.
Is the DC adapter connected to a live AC power source? Don't waste your afternoon trying to troubleshoot a power problem before you make sure that you have the AC adapter plugged into a live socket. Unplug the power cord and plug in anything you can check, like a radio (without batteries) or a light, into the same socket. Not the other socket in the outlet or power strip, the same socket. Power strips with surge suppressors and lit switches are particularly unreliable. I must have a number of them kicking around with one bad socket out of six.
Can you read the proper DC voltage with the connector cut off? If you can't get a reading off the barrel connector, making sure that you don't short it out while you're trying, then unless you plan to pry open the brick and check the switching power supply, you may as well assume that the connector end is bad. With the adapter unplugged, go ahead and cut the connector off the end of the cord a couple inches up from the injection molded barrel plug. Then you can strip the cord ends (we're talking about the DC output from the transformer brick mind you, not the AC cord from the plug that goes into the wall socket) and spread the two leads out nicely so they don't touch. Then you can plug the brick back in and use your meter to check for a DC voltage on the cord. If it's dead, unless you think you can fix a miniature switching power supply that isn't intended to be opened, it's time to spend $20 and buy a new one. If you do read the right voltage, all you need is a new connector you can splice onto the cord. I've had decent luck taking connectors to Radio Shack or my local electronics store and matching them up, but if you spend enough time searching online, you can usually find the exact connector dimensions on a spec sheet. Use "mm" in your search as the sizes are measured in millimeters.
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