Method that can be useful for troubleshooting a malfunctioning laptop is the bootstrap approach, which is especially good for what seems to be a dead system. This approach involves taking the system apart, stripping it down to the bare-minimum necessary functional components, and testing it to see if it works. Because laptops have fewer removable components, this approach can be a little trickier than when using it on a desktop PC. However, even with portables, the bootstrap troubleshooting approach is still viable. For example, to prep a laptop for testing, you would disconnect or remove the following items:
- Network cable.
- External mouse and keyboard.
- External modem.
- USB devices.
- Port replicator.
- Main battery.
- Hard disk.
- SO-DIMMs (except for one; note that many laptops have nonremovable memory along with one or more sockets for removable memory; in such cases, you should take out all removable memory).
- Bay devices (drives, battery, and so on).
Once you've removed these components, you power up the system to see if it works. If any of the removed components are defective, removing them should enable the system to start up, at least to the point where the Power On Self Test or splash (logo) screen is visible on the display. If the system displays this information, you know that the motherboard, CPU, RAM, video circuits, and LCD display are functional. If you don't see this information, turn off the system and plug an external monitor into the laptop computer and try starting it again. If the external display shows the startup information, but the internal display does not, the system might be misconfiguration.
If you can get the system to a minimum of components that are functional and the system starts, you reinstall or add one part at a time, testing the system each time you make a change to verify that it still works and that the part you added or changed was not the cause of a problem. For example, add an external harddisk drive and try booting from a bootable harddisk disk. If that works, then try adding a swappable hard drive. Essentially you are rebuilding the system, using the existing parts, but doing it one step at a time. If the system fails to start up properly after adding a component it's likely you've found the source of your problems.
Note : Removing the main battery and running the laptop from AC power is the single most important step to follow when you run a laptop in bootstrap mode. Defective batteries can cause laptops to crash, get stuck in suspend or sleep modes, and other problems.
Many times problems can be caused by corrosion on contacts or connectors, so often the mere act of disassembling and reassembling accessible components on a laptop "magically" repairs it.(I often use this method and 70% successful)
. Over the years I've disassembled, tested, and reassembled many systems only to find no problems after the reassembly. How can merely taking a system apart and reassembling it repair a problem? Although it may seem that nothing was changed and everything is installed exactly like it was before, in reality the mere act of unplugging and replugging renews all the slot and cable connections between devices, which is often all the system needs. Here are some useful troubleshooting tips:
- Eliminate unnecessary variables or components that are not pertinent to the problem.
- Reinstall, reconfigure, or replace only one component at a time.
- Test after each change you make.
- Keep a detailed record (write it down) of each step you take.
- Don't give up! Every problem has a solution.
- If you hit a roadblock, take a break and work on another problem. A fresh approach the next day often reveals things you overlooked.
- Don't overlook the simple or obvious. Double- and triple-check the installation and configuration of each component.
Keep in mind that batteries and power adapters are two of the most failure-prone parts in a laptop computer, as well as some of the most overlooked components. A "known-good" spare power adapter is highly recommended to use for testing suspect systems. If a system runs without the battery, but fails when the battery is installed, the battery is defective and should be replaced.
Cables and connections are also a major cause of problems. Keep replacements of all types on hand.
Before starting any system troubleshooting
, you should perform a few basic steps to ensure a consistent starting point and to enable isolating the failed component:
Turn off the system and any peripheral devices. Disconnect all external peripherals from the system.
Make sure the system is plugged in to a properly grounded power outlet.
If the LCD panel has a brightness control, make sure the display is set to at least two-thirds of the maximum. The brightness or brightness/contrast control might use a sliding switch or keyboard controls. Consult the display documentation for more information on how to adjust these settings. If you can't get any video display on the built-in LCD panel but the system seems to be working, plug in an external monitor and press the key combination needed to send video output to an external display.
To enable the system to boot from a hard disk, make sure no media is in a removable storage drive. In the case of laptops, this usually is either the external disk drive or CD/DVD-ROM drive (or both). Alternatively, put a known-good bootable external harddisk or CD with DOS or diagnostics on it in the drive for testing.
Turn on the system. Check the chassis fan (if any) and the lights on the system front panel. If the fan doesn't spin and the lights don't light, the power supply or motherboard might be defective.Note
The exhaust fan on a given laptop computer model might be located on the left or right side or the rear of the system. Laptop computers use very small and quiet fans, so use your hand to determine whether the fan is blowing air; you probably won't be able to hear it.