Quick Guide to Fixing Computer Hardware
by Howard Fosdick
Originally published in OSNews in 2012
Even those with no training -- like me -- can identify and fix the
most common computer hardware problems. This is your quick guide to
doing exactly that.
Here's the outline --
- Before you open up your computer, remember to unplug it. Unplug everything.
- Ground yourself! A
small shock you won't even notice can kill circuitry. Buy a $5
USD anti-static wrist
- Enter error messages to Google to see how others fixed your
problem. Why reinvent the wheel?
- Download your computer's User
Guide and Field
Service Manual if you don't have them. Most companies
offer free downloads.
- A 2" long Swiss
Knife includes a tapered screwdriver that fits nearly all
PC screws for about $15 USD.
Step 0: Identify the Problem
The first step in fixing any problem is to identify it. Don't jump to conclusions. Run
free diagnostic software for problem identification:
Don't know if your problem is hardware or software? Run a different
operating system. If the problem disappears, it's software. If you're using Windows, boot a live Linux
from USB or DVD to determine whether your problem is Windows or a
Here are the most common hardware problems and their solutions:
Laptop Unexpectedly Shuts Down
There could be many causes for this one -- a short circuit,
damaged electronics, and more. Most random shutdowns are caused
by overheating. Laptops are
prone to this because they cram so much circuitry into too small a
package for easy cooling. But it can happen to desktops, too.
Every computer has internal sensors that immediately shut down the
system to prevent electronics damage if the temperature gets too
high. Since you can not relate the timing of the shutdowns to your
actions, they appear random.
View your laptop's internal temperatures by running a free
other free monitors for Windows or use lm-sensors for
To fix overheating, ensure all fan(s) are spinning when they
should. Unclog the air vents. Make
sure you aren't blocking the vents by placing the laptop on your
lap or pushing your desktop up against a flush surface.
Don't pre-heat a laptop by leaving it in the direct sunlight or in a
car window. Use the computer in an air-conditioned room.
Open the computer and remove dust, especially that coating
circuitry. Since static
electricity kills electronics, don't rub circuitry with a dust
rag. Blow out dust with an inexpensive canister of compressed
If this doesn't fix your problem, you may need to replace the
fan(s). Fans burn out as their ball bearings fail. Here's
how to replace a case fan. If the computer has a CPU heat sink (a
metal flange that draws heat away from the CPU), you may need to
re-seat it. Here's
how to re-seat a CPU heat sink and the
Anyone who's downloaded their computer's service manual can perform
these procedures so long as they exercise care.
Computer Turns On But Won't Boot
You flip the power switch on and your computer appears to start up.
The power light goes on, the fans spin, maybe the disks kick -- but
nothing further happens. You can't get into the computer's
configuration (UEFI/BIOS) panels to perform problem determination.
That means you have a hardware problem.
Some computers will give you "beep codes" or
flash panel lights to tell you what's wrong. Look in your machine's
doc to decode them. Or visit this webpage.
Without beep codes or other indicators, this one's tough to
diagnose. You need a methodology to identify the problem. Here is
one that is time-consuming but effective in isolating a defective
component. It identifies these problems:
To start, turn off and disconnect the computer from power, open it
up, and write down where every wire, insertable adapter card, and
connector attaches to the motherboard and the devices. Record this
so you can reattach everything later. Then disconnect every wire or
plug from the motherboard, except for the power connectors from
the power supply. Detach all devices. Remove all adapter cards and
- Improperly seated or burned out adapter cards
- Faulty devices
- Loose or bad connector cables to devices
- Wires that aren't properly connected to the motherboard
- Improperly seated or defective memory sticks
Now you're down to a naked motherboard with its CPU, attached to the
power supply. Insert one good memory stick into the first slot
nearest the CPU, attach a working display (with a video card you
know works, if necessary), and turn on the computer. If you can't
access the configuration or UEFI/BIOS panels now, the motherboard or
CPU circuitry may be bad. Visually inspect the motherboard for
leakage, especially near the capacitors and battery. You might
succeed in cleaning up leakage, but most of these boards are goners.
If the system does display the UEFI/BIOS panels, the motherboard and
its embedded circuitry is good. One at a time, reattach each
connector or cable or insertable adapter card. After reconnecting an
item, turn on the computer. If you can still get into the UEFI/BIOS
panels, you know that whatever you just attached is
not causing the freeze-up or failure. As soon as you attach an
item and the computer dies, you know that that component was the
Here's an example. My friend's year-old computer completely baffled
him. It would start up, display the "HP Welcome" panel, and freeze.
He couldn't get into the configuration panels. I stripped the system
down to the Motherboard+CPU+OneMemoryStick+Display+PowerSupply. Then
I powered on and got into the UEFI/BIOS panels, so I knew the
motherboard and CPU were good. Then I attached each item, one at a
time, and booted after each, and got into the UEFI/BIOS panels.
Until I attached the SATA disk drive! Then the symptom
re-appeared. We replaced the defective disk and the system has
worked fine since.
Computer Won't Turn On
What if your computer won't turn on at all? Check the power supply
and ensure it's getting electricity. Was it plugged into a live wall
socket with a good power cord? Test the socket with a lamp. Don't assume that one socket in a
power strip is working just because the other sockets in the
strip work. If you just upgraded memory verify the secure
seating of the ram sticks.
Check the wire that goes from the Power On button to the
motherboard. If this doesn't connect you're not turning on the
computer at all. Is the power supply (PS) working? Did its fan spin
when powered on? Is the PS properly connected to the
motherboard? If you have a spare try the motherboard with
another power supply to see if a burnt out PS is the problem. Find
how to diagnose PS problems here. If you have a
volt-ohm meter (VOM) verify the current.
If these procedures don't work, try the disassembly/reassembly
procedure above. Sometimes you'll find a short caused by improper
connection this way.
Computer Boots into Windows But
Fails Somewhere Along the Way
computer boots and gets into the Windows start-up process, then
freezes or fails, nearly always you have a Windows software issue
rather than a hardware problem. To find out for sure, boot a live Linux
from USB or DVD. If everything works you have a Windows
problem. This is a hardware article so I won't address how to fix
Loses the Date or Time
If your computer loses the date or time across sessions, you
probably have a dead battery. This is the little round watch-type
battery that keeps configuration information across sessions, the CMOS battery.
Before you replace the battery, write it down any unique
configuration information you've entered into your UEFI/BIOS panels.
Because this procedure will erase it.
Now, pry out the battery and replace it. They cost only a few bucks.
After you install the new battery, update the date and time and
re-enter any unique configuration info into the UEFI/BIOS. Here's
how the battery might look on a desktop's motherboard:
Courtesy: www.PCTechNotes.com and www.TechNibble.com
With optical mice, the only cleaning you need to do is to ensure
that no lint is clogging the optical opening beneath the mouse. Sometimes
optical mice don't track well on glossy or transparent surfaces,
including some mouse pads.
If your plug-in mouse doesn't work at all, ensure the
connection is secure. Verify the operating system is using a valid
mouse driver. Test your questionable mouse on another computer or
plug in a different mouse to your computer. Reboot and test. This
shows whether you have a dead mouse rather than a software issue.
If your mouse is wireless, the most common problems are: (1) a dead
battery (2) a wireless connection problem (3) device drivers that
are not correctly installed, or (4) a dead mouse. Check the
batteries first. Ensure the wireless adapter or USB linking device
is securely plugged in. Verify the drivers. Use the wireless control
program to diagnose and resync the mouse. Try resyncing the
mouse by powering everything down, then rebooting.
Keyboard and Display Problems
If you prevent food, hair and other debris from falling inside your
keyboard, you've avoided 90% of all problems. To clean a keyboard,
detach it, turn it upside down and vigorously shake it. If this
doesn't work, carefully pry off sticky keys and eliminate the gunk
Desktop keyboards are so cheap you might as well buy a new one for
all but the simplest repairs. Laptops are another matter, with their
embedded keyboards. Here's
a good article on repairing laptop keyboards. And here
are several instructional Youtube videos. Hiren's Boot CD
includes keyboard testing programs.
What if you spill water or a drink onto your keyboard? Turn
everything off immediately.
Pull the power cord or push the Off button. Do not take the time to perform a
graceful shutdown! The longer electricity goes through the
electronics the greater the chance for permanent damage.
Do not touch or move the keyboard.
Wait a full day to ensure everything has dried out. Then, turn on
the system. If you're lucky it will work.
Cleaning the keyboard with rubbing alcohol or electronics
cleaner may be in order if you spilled a drink that will
become sticky after it dries. If you spilled water, don't bother.
Just let it all evaporate.
The principle about wet keyboards applies generally to computer
electronics. I've picked up computers left out in the rain or snow,
let them dry out, and used them without any ill effects. Just dry them out completely before powering on!
Desktop displays are black boxes. The usual remedy is replacement.
But verify you don't have a device driver or software issue before
junking your display. With laptops you have to buy a replacement
screen for your specific laptop model and install it. Here are some
Youtube videos showing how to replace laptop screens. Anyone
can successfully replace laptop screens and keyboards -- if they download model-specific
documentation and follow it carefully.
Sometimes you'll get a stuck
pixel on a LCD screen, a pixel that inaccurately remains an
out-of-place color like green or red. Use a felt cloth to
gently rub around the bad pixel in a circular motion. If you can
get the pixel to light properly, hold the pressure there for a
minute or two, and this often fixes it.
Optical Disc Problems
If your optical drive doesn't work, new
ones are cheap. But first check all connectors, ensure the OS
recognizes the device, and that you have a working driver installed.
What if the problem is sporadic? Try cleaning the drive with these
simple cleaning techniques.
Another possible cause is differing calibration between drives. It's
possible to write a disc on one system and find another unable to
read it. Determine if you have a calibration difference by testing
multiple discs on several different drives.
You might find that your drive works well with certain brands of
disc media but not with others. Media
differences can cause sporadic problems even with healthy optical
drives. Remember that there are many optical media
standards and that you have to match them properly to the drives
that use them. While current drives support multiple media
standards, you can't always mix all media in all drives (DVD+R,
DVD-R, DVD+-R, DVD-RAM, Blu-ray, CD-RW, CD-ROM, etc).
What if your problem is a particular disc? Clean the disc by gently
rubbing it from the inside
towards the outer edge. Remove any fingerprints. Sometimes
wiping with a dab of distilled water will work. Other times, more
aggressive techniques are necessary. This article has
a progressive list of steps you can work through to restore a
disc to a readable state. It includes my favorite -- cleaning the
disc with toothpaste. It often works! But read the entire article
before you try it.
What if a DVD gets stuck in the drive? Look closely at the drive
face and you'll see tiny hole. Stick a straight pin in there
and push a lever that will mechanically push out the tray. Do
this with the computer powered off since it is solely a mechanical
Memory errors are easy to fix. Simply remove and replace the bad
memory stick. The problem is identifying that you have a memory
error, since many are transient
(they occur sporadically). If you suspect a memory problem, run
an intensive memory checker utility like Linux's Memtest86 or Hiren's Boot CD.
Take the time to run the long or extended test (not the short or
quick test). Run it overnight if necessary.
You can also set the UEFI/BIOS configuration to test the memory upon
startup at the expense of a longer boot. This test will not
be as thorough as Memtest86 or Hiren's.
When you add memory into your computer, ensure it's seated
correctly before booting. If the memory is not inserted
properly most computers will beep and refuse to boot, telling you to
re-seat. Hopefully no damage resulted. After adding memory, enter
your UEFI/BIOS configuration panels to ensure it's properly
recognized before booting
all the way into your operating system.
A million things can go wrong with disks. If it's a software
problem, you can fix it. If it's a hardware problem, buy a new disk.
Messing with faulty disk hardware is not worth your time -- with two
- You need data only available from that disk (you don't have a
data good backup)
- You need to save your copy of Windows and the installed
applications (you don't have a backup of Windows and the apps,
and have no way to recreate them)
The best insurance against disk failure -- by far -- is good
To test if your disk is working, most computers' configuration
panels (the UEFI/BIOS startup panels) have drive diagnostic and test
procedures. You can also download the disk drive manufacturer's free
drive-specific diagnostic program, which is often more effective
than the computer's own tests.
Here are common disk symptoms and how to fix their underlying
"Operating System Not Found" Error
When booting your computer, you might get an error message like one
These are all software errors.
computer is telling you that the boot record and/or partitioning
data stored on the disk are either missing or corrupted. You can
often fix this issue using tools like free TestDisk
utility. Here and here
are tutorials for Windows users.
- "Operating System Not Found"
- "No Operating System on Disk"
- "Missing Operating System"
- "Invalid Partition Table"
OS Detects the Drive But You Can't
Access Your Data
Sometimes Windows knows a drive is present but won't let you use it.
Or it tells you the drive needs to be formatted. Or maybe it just
shows a blank drive that doesn't contain any data. Or it won't show
you the drive properties or let you format it. Usually this means a
You can fix a filesystem to recover all or nearly all of your
data. Here is a quick list of fix/recovery tools (with more here):
Disk Digger, PCInspector
Recovery, Linux dosfsck
||Lots of free and shareware tools here,
DTIDATA's tool, TestDisk
|ext2, ext3, ext4
|Use built-in Linux utilities like fsck, e2fsck, ddrescue, etc., TestDisk, DiskInternals
It's possible to have a hardware problem that shows the same
symptoms. Dirty contacts between drive and cable are one possible
cause. Just clean the contacts with a Q-tip, toothbrush, or pencil
eraser. Many use isopropyl alcohol (90% grade or better) with their
cleaning tool. Just use don't drip the alcohol anywhere and make
sure you leave no Q-tip fibers or eraser crumbs behind!
Drive is Not Detected At All
Make sure that drives have fully connected power and data cables.
You could get a variety of errors from this but "drive not detected"
is common. Check the data cable connection to the motherboard as
well as the side that connects to the back of the drive.
Hard Disk Problems
If you're still using old hard disks (HDDs), they have their own set
of issues. They have mechanical features that newer solid state
disks (SSDs) lack, such as spinning platters and movable read arms.
Rules of thumb for fixing hard drives:
- Download the disk drive manufacturer's free drive-specific
diagnostic program. Some can fix disk errors.
- Most UEFI/BIOS's have drive diagnostic and test procedures.
These may not be as thorough as those you download from the
- Never open a hard drive enclosure (it is sealed to remain dust
free and you can't fix anything in there anyway)
- As long as a hard drive still spins you can recover all or
nearly all of your data.
- You can get your data back by spending money instead of
time by sending the drive to an expensive data recovery service.
If the drive is truly dead, this is your best option.
Hard Drive Makes Clicking Noises
This is the so-called Click Of Death.
Drives make clicking noises when they have to move the disk arm
multiple times to retrieve data. The drive is not functioning
properly and this is its error correction procedure. Your drive may fail very soon!
Copy any data you need off there immediately.
You may have limited time so copy files in priority order.
If you can not get in to copy data off by normal means, here
is a procedure that extracts data from even the most recalcitrant
drives. It's more detailed than I can describe here but the key
ddrescue tries every trick
in the book to read the data off the target drive, bit-by-bit,
regardless of what filesystems or partitions the drive contains. It
will even try to read the data backwards. It's very effective. But
it might take many hours or even days to get your data back. Like
all the software in this article it is free.
- Hook up a second target drive to the controller (or you can
use a USB thumb drive as the target)
- Use the ddrescue command to
copy the raw drive image from the failing drive (instructions here)
- Make the target partition active so you can access your
Drive is Not Detected At All
First, always make sure that the cabling connecting the drive
to the motherboard is fully seated at both ends. This is the most
Another possible cause of "drive not detected" problems is a failed
logic card on the drive. This is the circuit board attached to the
underside of the drive. The board circuitry may fail over time due
to the heat coming off the drive and the temperature differential
from the powered-off state.
Take off the drive's circuit board and replace it with another. You
can buy one on the web or take one from another drive. The key to
success is that the logic board must be for the exact same drive.
If not, it will not work. Obviously, you'll only go to this trouble
if you really need the data on the drive and have no backup!
Hard Drive is Not Spinning
If the drive is not spinning, most people assume it is dead.
Usually, but not always. I've read about supposed home remedies like
freezing or hitting the drive. But if you really must retrieve
your data from that drive, don't mess with it! Instead, pay a
professional data recovery service, like Data Savers or Ontrack. They often succeed
because they ignore the drive hardware and instead directly analyze
its storage media.
Your computer has many different kinds of "ports" (or plug
receptables). These include ports for USB devices, SD and similar
memory cards, monitors, sound and speakers, microphones, and so on.
From the hardware perspective, the most common problem is dust
getting into ports that aren't frequently used. Make sure your
computer is turned Off, then clean the port by a Q-tip or
toothbrush, if necessary enhanced with a small drop of isopropyl
alcohol (90% grade or better). Check inside the computer to ensure
that no connecting wires from these ports have become disconnected.
Lastly, verify that your operating system detects the port and has
installed a suitable driver for it (if needed).
There's much more to fixing computer hardware than any one article
can cover. Yet this quick overview solves perhaps 90% of all
hardware problems. Yes, you can fix it!
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Howard Fosdick is an independent consultant who supports databases
and operating systems. He fixes old computers for fun and charity.
Read more how-to's and tutorials here.
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