How to fix hardware problems

In this guide I show how to work around some common laptop hardware problems without taking it apart.
1. Network port failure.
Most motherboards have the network port permanently attached. If the network port fails (I’m talking about hardware, not software failure), the whole motherboard has to be replaced.
Instead of replacing the motherboard, you can use a PCMCIA network card. You plug this card into the available PC slot in your laptop and you are back in business.

If you computer doesn’t have a PC slot, you can use a USB Ethernet adapter instead.

2. USB ports failure.
Most laptops have a few USB ports available. If one of them stops working, usually it’s not a big deal because you still have two or three more working ports left.
But what if all of them stopped working at once? Let’s say the USB controller on the motherboard went bad and the laptop stopped recognizing any device plugged into any USB port. Again, I’m talking about hardware, not software failure. In order to fix this problem you’ll have to replace the motherboard.
Alternatively, you can use a PCMCIA USB card. You plug this card into the PC slot and get two or four USB ports instead. It depends on the type of your PCMCIA card.

3. Internal wireless (Wi-Fi) card failure.
What can you do if the internal wireless card failed?
You can replace the failed wireless card with another one or use a PCMCIA wireless card instead.

4. Internal flash memory card reader failure.
Most newer laptops come with a flash memory card reader. Usually the card reader is soldered directly to the motherboard and if it fails, you have to replace the whole motherboard.
Alternatively, you can use an external USB flash memory card reader. All you have to do is plug the card reader into the available USB port and it’s ready to go.

5. Internal CD/DVD drive failure.
You’ll find an internal CD/DVD optical drive in most computers. If the optical drive failed and stopped reading discs, it has to be replaced with a new one.
Instead of replacing the failed drive, you can use an external USB drive. Simply plug this drive into the USB port, let your computer detect the drive and it’s ready for you.
Also, you can use this optical drive with any other computer which is very convenient.

How to test screen inverter

In this post I explain how I test the inverter board in a laptop.
The inverter failure is very similar to the backlight lamp failure. In both cases the screen gets very dark and the image becomes very faint, barely visible under a bright light.

There is only one reliable way to test the inverter – replacing it with another one and see if the screen lights up after that.
Alternatively, you can connect a new backlight lamp and see if your presumably bad inverter lights it up.

In most cases I go with the second method – using my test backlight lamp. Why? Because the same backlight lamp will work with many different inverters as long as they have matching connectors.
Usually the inverter is mounted inside the display panel below the screen. In most cases you can access it after you remove the display bezel. The inverter has connectors on both ends. The left side connects to the LCD cable. The right side connects to the backlight lamp which is mounted inside the screen. Check out this display diagram.
To make sure that inverter gets power from the motherboard (via the LCD cable), you can test it with a voltmeter. In my case I connected the “+” lead of the voltmeter to the pin 1 and the “-” lead to the ground trace around the screw hole. I got about 19.4V DC on that side of the board, so it’s getting power from the motherboard.
WARNING! If you accidentally short something on the inverter while testing, you can damage it. Proceed on your own risk! Not sure? Don’t do that!

So far we know the inverter is getting power from the motherboard, but the screen still has no light. Apparently, it’s either bad inverter or failed backlight lamp.
Now let’s test it with a known good backlight lamp.
1. Unplug the screen backlight cable from the right side of the inverter.
2. Connect a known good backlight lamp.
Turn on the laptop.
1. If the test backlight turns on, the lamp inside the screen is bad. In this case you’ll have to replace the screen. Also, you can replace the backligth lamp which is not easy and not recommended.
2. If the test backlight doesn’t turn on, most likely we have inverter failure. Replace it and test the laptop again.

There are two different types of backlight connector, you can see them on the picture below. The top one (big) is not as common as the bottom one (small). I mostly use lamps with a small connector.
IMPORTANT! When you buy a new lamp for test, make sure the connector fits your inverter.

On the following picture you see how I’m testing the laptop with a new lamp.

Related articles:
Troubleshooting backlight failure.
Screen shows strange colors.
Troubleshooting video problems.

How to modify damaged DC jack

In this guide I explain how to modify damaged DC jack. While replacing the DC jack a few days ago I accidentally damaged one of the thermals on the motherboard.
I pulled out the internal copper coating (I name it a sleeve) from the inside of the “+” terminal as it shown on the picture below.


The the sleeve removed, it cannot be installed back. If you solder the DC jack back in place without this sleeve, it might work but the connection between the “+” lead and motherboard will not be reliable.
The following guide will help you to modify damaged DC jack terminal. This modification should work for most motherboards with soldered power jack.

Remove the copper sleeve from the “+” terminal on the jack.

Find a small resistor or capacitor with thin leads. Cut off one of the leads. I’m going to use it to modify the motherboard terminal.
Shape the lead as it shown on the picture below.

Put the lead on the “+” connector on the power jack.

Solder the lead to the power jack.

Now I’m going to modify the “+” terminal on the motherboard.

Carefully scrape off green varnish around the whole on the “+” terminal on the motherboard. You can use a small flathead screwdriver.

If the whole is not big enough for your modified DC jack, you can widen it with an awl.

As you see, the hole on the terminal is now larger. Apply a fresh coat of solder on the clear area of the trace.

Install the power jack on the motherboard. Make sure there is no gap between the jack and motherboard.

Here’s a view from the top side of the PCB.
Solder all pins except the modified “+” pin.

Now, when the power jack is secured, you can shape the lead as it shown on the picture below.

Solder the lead to the terminal. Remove excessive flux with an old tooth brush soaked in 99% alcohol.

Here’s a view from the bottom side of the motherboard.

Be very careful. Doing this modification you can damage the motherboard and make it unusable. Proceed on your own risk.

Installing USB Bluetooth adapter inside

Here’s how I installed an external USB Bluetooth adapter inside my laptop case.
My old computer wasn’t Bluetooth ready, it didn’t have the internal connector and antenna for it. I decided to modify my USB dongle and move it inside the case.

I didn’t want to use my laptop with an adapter sticking out from the side.


First of all, I installed Bluetooth adapter software on my computer to make sure everything is working fine while it’s connected to the USB port.

For this modification you’ll need:
1. Laptop disassembly experience.
2. Soldering skills and tools.
3. Inexpensive USB Bluetooth adapter.
This modification is only for experienced users.  You can damage your computer. Proceed on your own risk!
This guide should works for most computers as long as you have enough space to mount the Bluetooth module inside the case.
First of all, I disassembled the case and found a place for the adapter.
In this guide I’m modifying a Toshiba Satellite A105.

My idea was simple. Remove the Bluetooth adapter circuit board and solder it directly to one of the USB ports.
NOTE: after this modification one of the USB ports will not work.

I found some thin wires laying around.
Make sure that wires are long enough for your project.

Disassembled the adapter and remove the circuit board.

Unsolder the USB connector.

The circuit board easily fits into the empty place inside the laptop.

I soldered four wires to the circuit board. I used terminals for the USB connector.

After that I soldered wires to the back of the USB port.

At the last step I installed the Bluetooth circuit board into the case and routed wires to the USB port.
I secured wires to the motherboard with electrical tape.

Finally, assembled the laptop and tested it. There is no on/off hardware switch for the Bluetooth module but I can turn it on and off through software.

Later I found that the reception range wasn’t as good as for external adapter but it was enough for me.

New screen installed but not working

If you installed a new screen into the laptop and for some reason it doesn’t work, there may be a few  things you could have done wrong.
Lets figure out step-by-step how to troubleshoot and  and fix the problem.
First of all, I assume that your new LCD is compatible with the original one. If the screen looks identical, it doesn’t exactly mean it’s compatible. Double check the compatibility between the original and new LCDs.


Troubleshooting LCDs with CCFL (backlight lamp)

The old style screens have a backlight lamp inside and require an inverter board which is usually mounted on the lower part of the display assembly, as you can see on the following picture.

On the following picture you can see how the screen connected to the laptop. Also, check out this display diagram.
The video cable routed from the motherboard to the display through one of the hinges. Somewhere close to the hinge, the cable splits. The wider end connects to the screen (supplies data signal) and another one to the inverter board (supplies power for inverter).

If your new screen lights up but has no image make sure the video cable plugged correctly. It’s possible that during the reassembly process you accidentally pulled the cable from the connector.
Reconnect the cable, secure the connection with sticky tape and test the laptop. There is a chance that now the screen will work properly.

The video cable has to be seated properly, all the way down into the connector.

Some older LCDs have very thin pins inside the video connector as it shown on the following picture.
Take a look inside, make sure there are no damaged (bent) pins. It’s possible that you accidentally bent them while trying to plug in the cable.
You can straighten bent pins with a very small screwdriver. Be careful, they are very fragile.
Fortunately, most newer LCDs have a different type of connector, without any pins inside.

OK, you have reseated all cables but it still doesn’t work. What’s next?
If your original screen was cracked but undamaged areas still work and show some image, you can use it to test the laptop.
Disconnect the new LCD and install the old damaged one back in place. If the old screen still works but the new one doesn’t, your new screen is defective. Send it back to the seller for a replacement.
Here’s another scenario. The new screen kind of works. You can see a very faint image but there is no backlight.
Disconnect the new screen from the inverter board and plug in the old screen instead (I assume it has working CCFL), as it shown on the picture below. If the original screen lights up, apparently the new screen has defective backlight lamp.

 

Troubleshooting LED-backlit LCDs

Newer LED-backlit LCDs have only one cable connected to it. This cable supplies data signal and power for LED backlight.

If your new screen doesn’t work, check the connection first. Make sure the cable seated properly, all the way down into the connector.
You can test the computer with the old, partially working screen, as we did earlier. If the old one still works, but the new doesn’t, your new screen is defective or not compatible.
Also, you might be interested in how to troubleshoot bad video.

Battery not charging if connector moved

This laptop has a power problem. The battery stops charging when I move the AC adapter connector inside the jack. When the connector or power cord moved, the battery charge LED light on the front goes on and off.
Let’s troubleshoot this problem and figure out if this is DC jack related failure or the AC adapter is defective.

First of all, I tested the laptop with the battery removed. It turns on and runs properly from the AC adapter but as soon as I start moving the connector inside the jack the laptop shuts off and it loses power immediately.
If you have a problem like that, most likely it’s related to the AC power adapter or the DC jack.

First of all, I tested the adapter with a voltmeter. The power didn’t cut off no matter how badly I wiggled the cord. I was reading 15.45VDC all the time. It helped me to make a conlcusion that there is nothing wrong with the adapter connector or cord and most likely there is a problem with with the power socket inside the laptop.
The next step was the DC jack inside the laptop.

In order to access the jack I had to disassemble the laptop and remove the top cover assembly with the display.
You can find disassembly instructions for most laptops in their service manuals.

In my case the DC jack was attached to a cable and I easily disconnected it from the motherboard. I tested it with the voltmeter as it shown on the following picture.
When the adapter cord didn’t move, I was reading 15.45VDC.
But as soon as I started wiggle it, the voltage dropped to 0VDC.

The DC jack harness is defective and had to be replaced and the new one fixed the problem.

In some models the DC jack is soldered to the motherboard.
If the battery stops charging when you move the adapter plug, test the AC adapter first. If it pass test, replace the jack.

Laptop is dead. How to troubleshoot.

In this post I’ll explain how to troubleshoot a dead laptop and find the problem. The following troubleshooting tips are not model and brand specific.
Let’s take a look at different failure scenarios.
Example 1. The computer is absolutely dead. 
When you plug in the AC adapter and press on the power button, there are no signs of life at all. It appears to be dead.
What you can do ?
1. Make sure the wall outlet is working and the AC adapter is getting power from the outlet. Try another wall outlet.
2. Test the AC adapter, make sure the voltage output is correct. You can test the adapter with a voltmeter.
3. If the adapter is good, try reconnecting the battery. Remove the battery, wait for 1-2 minutes, plug in the adapter and try turning it on again.

If the adapter doesn’t pass the test with a voltmeter, replace it with a new one and test the computer. I always recommend buying an original replacement adapter from the manufacturer, not a generic one.
There could be more than one adapter available for your model.
The voltage output on your new adapter must be exactly the same as on the old one. The amperage, on the other hand, can be the same or higher.
If previous troubleshooting steps didn’t help, it’s possible your computer has a problem with the motherboard or DC power jack. In this case it’s necessary to disassemble the laptop and test the DC jack.
Example 2. The computer turns on and makes normal startup noises, the LED lights turn on but noting appears on the screen.

First of all, take a closer look at the screen under bright light. It’s possible the screen shows the image but it’s very faint. In this case you’ll have to troubleshoot the backlight failure.
On the other hand, if the screen shows no image at all, test the laptop with an external monitor (or TV) connected to the VGA port or DVI port or HDMI port.
You can toggle video output between internal and external modes by using Fn keys:
– Fn and F4 keys simultaneously on HP laptops
– Fn and F5 keys on Toshiba laptops
– Fn and F7 keys on IBM laptops.
Other laptops may use different key combinations.

If the external monitor works fine but the internal screen has no image at all, the problem can be related to:
– Poor connection between the video cable and screen or motherboard. Try reconnecting the video cable on both ends and check out if this helps.
– The screen failed. Replace it with a new one.
– The video cable failed. Replace it with a new one.
– The motherboard failed.

If both, the internal and external monitors show no image, the problem can be related to:
– Failed memory (RAM).
– Failed motherboard.

– Try reconnecting the memory module, maybe it’s not making good connection with the slot.
– Try cleaning contacts on the memory module.
– Try moving the memory module into another slot.
– Try replacing the memory module with another one.
If you have two modules installed you can try removing them one by one, it’s possible that one of the modules failed. Try moving modules from one slot to another.
If changing or reseating memory doesn’t help, you can try this:
Removing the battery, hard drive, DVD drive and other components you can easily access. Try turning on the laptop without these components installed.
It’s possible one of them failed and it’s preventing the entire computer from starting up properly.

Also, try turning on the laptop with an external monitor while the video cable is unplugged from the motherboard.
If external image appears after you disconnected the video cable, apparently there is something wrong with the cable. Replace it with a new one.

If the computer is still dead, try removing other internal components (wireless card, modem, keyboard, etc…) and test it with an external monitor after each removed part.

The last step is testing the laptop as a barebone system.

On this picture you see my final test. The motherboard has been removed from the base and I assembled a basic barebone system on my bench.
The bare bone system includes:
1. Motherboard (like in most cases it has onboard graphics chip).
2. CPU with the cooling module.
3. Known good memory module.
4. The power button board.
5. Known good AC adapter.
If the system still doesn’t turn on, it’s either bad motherboard or failed CPU.
If you computer shows garbled or distorted image, check out this post.