Basic PC Laptop Troubleshooting
Today we are going to look at the basic principles of troubleshooting your non-working or partially working PC laptop. You might be surprised to find out that there isn’t a whole lot to solving some of the most common problems that can potentially arise with your laptop.
We are going to address the following seven conditions, one at a time:
- Laptop powers on, but there is no video display on the LCD
- Laptop powers on, displays boot screen, and then hangs/freezes
- Laptop does not power on, power LED lights up
- Laptop does not power on, power LED does not light up
- Laptop blue screen errors during Windows setup
- Laptop randomly turns off, but turns back on right away
- Laptop LCD displays WHITE screen / Vertical Bars / DIM backlight / or Graphical Distortions
1. If your laptop powers on, but displays NO video, the first thing you should do is hook it up to an external monitor. Boot up the laptop while pressing the appropriate Fn + Fkey toggle for external monitor display. If you receive a video display on the external monitor that means your system board is likely OK. If you still don’t have a signal on the external monitor either, the motherboard may be suspect. You can also remove the RAM and re-seat it or better yet, replace it with different RAM. You would not believe the amount of times a computer has been marked bad, when all that was keeping it from working was a bad stick of RAM. A last ditch measure that has worked on a few units over the years is to turn on the laptop and leave it plugged in for a few hours, sometimes it will eventually POST and start working, booting normally. We have brought a few units back to life doing this over the years!
2. If your laptop powers on, displays boot screen with manufacturer logo, and then hangs; you should re-seat or replace the RAM with a different stick as the first measure, trying BOTH memory slots. Otherwise, some models will take longer to POST if they are missing components like HDD or CD drive. They may appear frozen at first, but will eventually go into the BIOS after a few minutes.
3. If your laptop does not power on, but the power LED lights up (indicating charger connected); you should try removing the RAM and replacing with another stick. Second, remove the battery and try powering the unit up with just the charger connected. Sometimes batteries will develop internal shorts that are insignificant, but enough to keep the laptop from booting. Third, with battery removed and charger disconnected, hold power button down for 5-10 seconds, reconnect charger ONLY and attempt powering on again. Certain model laptops have a separate PCB board for the power button, these can and DO fail. So be sure to do some research on if your model uses such a setup. Sometimes these power board buttons don’t completely fail, but they take a very firm push or a push in a certain direction. So pushing the power button in many different ways is also recommended as last resort. Also if your computer has “media” buttons near the power button, try using those as a power button! We have had laptops with defective power buttons, but the button for sending an email also powers on the unit too!
4. If your laptop does not power on, and the LEDs do not indicate a charger is connected; this is usually the least “curable” of the problems above. Wiggle the charger jack with adapter plugged in to see if its loose or cracked. Try removing the battery and use just the AC adapter to power on. On very rare occasions we have seen a bad stick of RAM causing the unit to not receive any power at all, yes, RAM does account for a LOT of your typical problems, as you can see. Otherwise the system board will need R&R.
5. If your laptop displays blue screen errors, or more loving referred to as BSODs, during Windows setup there is usually only a few things that cause this. Again, RAM is the number one culprit for blue screens during setup. Remove/replace one stick at a time if you have two sticks until it stops blue screening. If you have part of your RAM onboard (as is common with older and portable models), and that is responsible for the errors, you are out of luck. Only a new motherboard will solve your woes. Believe it or not, bad CD drives OR dirty discs are the second leading cause of blue screen faults during setup. Usually replacing/cleaning the disc is the first thing we try. Otherwise the drive needs replacement. Although if you have some rubbing alcohol and a lint-free cloth you can clean the “eye” of your laptops CD drive and that works about 50% of the time in getting it to read discs reliably again.
6. If your laptop randomly turns off, but powers back on there are two possible culprits. The first is heat related issues, and these are almost always associated with P4 laptops, but I’ve seen it in other Intel and AMD models too. Every laptop has built-in monitoring for temperature readings that will kill the laptop if it reaches a pre-determined temperature. These temperature readings typically come straight from the CPU die, which is covered in a small layer of thermal paste or a thermal pad. The problem is that after years and years of dust buildup, heat cycles, and use, that paste/pad turns into a hard, brittle, sometimes chalky substance that isn’t doing much of anything in terms of heat dispersion. It’s actually insulating! Combine that with dust build-up and the fact that most laptops are not really well designed in terms of airflow, and you can have a laptop that will not stay on for more than a few minutes before powering down. Half of the time these thermal protection shutdowns are not occurring because your laptop is actually overheating, its because the heatsink paste is so far degraded that it’s causing max temperature readings to be sent out when actually the CPU is running at normal operating temperature. The other half of the time it actually is overheating, because of excess dust build-up and heatsink paste degradation. Cleaning out the dust and replacing thermal paste will get you running again, use ISO rubbing alcohol and a lint free cloth to clean the old CPU paste off. Place a RICE sized grain of new paste in the center of the CPU die and evenly spread. The second culprit I have seen cause this random shutdown issue is a bad AC adapter; trying another AC adapter is always advisable before junking the system board for another.
7. If your laptop displays any one of these symptoms (White Screen, Vertical Lines or Bars, DIM screen, Graphical Distortions) it can always be confusing as to exactly what causes what. A white screen means NO data is being sent to the LCD, and is ALWAYS the LCD cable, the screen itself is fine. Vertical lines and Bars indicate the actual LCD panel is defective and will need replacement. DIM screen means that the LCD inverter or LCD backlight tube has gone bad. The LCD inverter usually sits directly under the LCD panel and does exactly what its called. It’s a power inverter for the LCD, which means that a lot of current is being run through it at all times. They are relatively easy and cheap to replace. In my experience it’s almost always a coin toss as to which it will be. Of course replacing the LCD inverter first is a wise idea. But there are a few signs that could indicate one way or the other for you. If the LCD displays or has displayed a RED TINT when first turned on, that means the actual backlight tube is at fault. If the LCD will turn on at normal brightness for a few seconds or minutes, and then go dim, the inverter is usually the culprit. I would not recommend replacing the backlight tube yourself, replacing the entire panel is a much safer move. R&R’ing the backlight tube involves heavily disassembling the LCD panel and cautiously removing the fragile g-l-a-s-s backlight tube (which contains mercury, by the way). Lastly, graphical distortions are either caused by the video card or RAM (if shared video memory). If you have shared video memory, try replacing the RAM, if that doesn’t work the video card that is soldered directly to the motherboard is bad and new motherboard will be required. If you don’t have shared graphics, you can just replace the graphics card to fix the issue. If you have distortions on the internal monitor, but NOT the external monitor the LCD panel will need to be replaced.
That covers about all of the most common conditions that we’ve run into consistently. There are a whole host of other issues you can have once the OS is installed, and we’ll be surely covering those at a later date. Soon we will be looking to the other end of the spectrum; Basic Apple Laptop Troubleshooting (G3 to Intel).
Thanks for reading. We hope this information will assist you in your laptop related endeavors!