Introduction: Repair an LCD Monitor With Back Light Issues

Picture of Repair an LCD Monitor With Back Light Issues

This Instructable will show you how to disassemble a monitor for repair, as well as the repair itself. In this Instructable, I will be working with an HP F1703 monitor which has developed cold solder joints and has caused an issue where the back light of the lcd monitor will only be be on for (more or less) 3 seconds. This solution can be applied to most monitors which have this issue. However, every monitor will be slightly different due to different design ideas. This will only be used as a guide and not a step by step instruction unless the monitor you have is an HP F1703 monitor.

Please note: Only proceed after contacting the manufacturer. There are many situations where there still may be a warranty or they may still be able to help. 

Materials list:
 - The broken monitor
 - Screw Driver set which includes both phillips and flat head screw drivers.
 - Soldering iron (can be purchased at your local electronics store for around $10-$15)
 - Solder - .022" lead-free solder is recommended. Possibly one size smaller because the parts that you will be working will be VERY small
 - Solder sucker or solder wick
 - Towel
 - Container to place screws and other misc. small parts
 - Knowledge about how to solder - I will not be instructing you on how to solder. It is up to you to learn how. There are many YouTube videos instructing on the basics of soldering. 

Caution:
 - The soldering iron will be VERY HOT!!! Soldering irons heat up to 500+ degrees F and will burn you instantly
 - Make sure you have a soft surface to place parts on. The LCD screen itself will need to be placed on something that will not scratch it.
 - You will need to take note of where everything goes so you can reassemble the monitor. Because this Instructable will not apply to all monitors, you cannot simply follow this exactly step by step.

Step 1: Detatching the Base

Picture of Detatching the Base

On the back of the monitor, there will be at least 2-4 screws which will be holding on the base/stand of the monitor. In many cases, these screws will be covered for aesthetic appeal by the company. In this case, HP used rubber plugs to fill in the holes where the screws were. To remove these, simply take a tiny screw driver and wedge it between the rubber plug and the sidewall. After removing the plugs, continue to remove the screws. Be aware, the LCD panel may fall forward after removing the screws.  

-Sidenote: For other brands, I have encountered a complete plastic cover which covers these screws. This cover is usually attached with clips and will detach with some outward force from one corner. An example of this will be shown in the next step. 

Step 2: Removing the Front

Picture of Removing the Front

To begin opening up the monitor, we must first remove the front covering. Typically, the front covering is attached via clips which surround the edge. To unclip the front, we must first begin in a corner. I recommend one of the lower corners as shown in the photograph. Starting is always the hardest step. You may need a flat screwdriver to pry apart the front and back coverings. This is why starting at a lower corner is a good idea. If damage does occur, it will be on the bottom of the monitor and very hard to see. 

-Side note: The front panel buttons may be attached to the front covering. In this case, the buttons were mounted to the back covering. But if they are attached to the front, remove the buttons from the front to make the process easier.

Step 3: Removing LCD Panel From Frame

Picture of Removing LCD Panel From Frame

For this step, you will want to remove the LCD panel from the back covering to access the circuit boards. To do this, you must first remove all of the screws which secure the panel in place. The screws will be located around the edge of the monitor. To prevent the panel from falling out and breaking, I recommend that you set the panel on its' backside so it cannot fall out when the last screw is taken out. 

-Optional: You may unscrew the buttons from the back panel, but it is not necessary. However, this will make the panel easier to handle and will prevent the wires, which connect them, from breaking.

Step 4: Removing Shields

Picture of Removing Shields

After removing all of the plastic surroundings, you will be left with the bare bones of your LCD monitor. However, there will still be some protective coverings. These are used to protect the important circuit boards. One of which that has a problem. To remove these coverings, simply remove any tamper evident tape and or screw which is holding it in place. In this case, the only thing that was holding the shield in place was the tape. After removing the tape, slide out the shield to expose the circuit boards.

Side note: The shield was also held on by the screws which hold the video cable in place. You may need to remove these to remove the metal shield. 

Step 5: Disconnecting Back Light Cords

Picture of Disconnecting Back Light Cords

Every monitor will have some sort of back light which allows the user to see the images displayed on the LCD screen. You will need to unplug these cables to remove one of the two circuit boards. Make sure to document which cable is plugged into which port. There may not be a discrepancy between the cables so make a note by either taking a picture, or marking the cables with a sharpie.

Step 6: Identifying Circuit Board Purposes

Picture of Identifying Circuit Board Purposes

Let us continue by determining which circuit board we will need to focus on. It is very simple to determine what the job is for each board. The easiest way to determine what the boards do is to look at the plugs on the board. The arrow on the left is pointing to the connector which provides power to the system. The arrow on the right is pointing to the VGA connector which is used to input the video from the computer. 

Now because because the issue is that the monitor will not stay powered on, we know that it is an issue with the power board because the monitor is either not getting enough power, or it is failing. 

From here, we will remove the power board. It will be attached with approximately 4 screws. Since we have already unplugged the back lighting cables, we can remove the screws and safely remove the power board. 

Key points:
     Left arrow: power board
     Right arrow: video board

Step 7: Removing Protective Coverings

Picture of Removing Protective Coverings

There may be another protective covering on the circuit boards. These plastic protective coverings are used to prevent the components from short circuiting on any other metal surface. 

Step 8: Identification of Issues

Picture of Identification of Issues

Because I was not able to get a clear image of the real problem due to my camera lacking the ability to take close-up pictures, I was forced to resort to non-original photos that I found on the internet; Wikipedia to be specific. Shown in the image are examples of different cold or broken solder joints. These can be found by simple observation. The most common failure is the cold solder joint. The solder will appear to have a dull appearance. A good solder joint has a bright shine to it. Another failure that may occur is broken solder joint. These joints will appear to have cracks. Both of these solder joints will reduce conductivity between the different components on the board, to the board itself. This explains why the monitor will only turn on for a few seconds. 


The image used for this step was taken from http://en.wikipedia.org/wiki/Soldering to be used as an example. 
This page will also be very useful for learning more about the different types of soldering.

Step 9: The Repair

Picture of The Repair

Now that we know the issue which we are trying to fix, you can now take your soldering iron and proceed to repair. This step cannot be very detailed because cold solder joints can by found anywhere there is solder and it is impossible to point yours out with a picture. Since I have identified how to find the problem, from here, it is up to you to find the cold solder joints on the circuit board and repair them. To fix the cold solder joints, I recommend that you remove as much solder from the joint with your solder sucker/wick and replace it with new fresh solder. This way, it will ensure that the solder that is on the board is not bad. 

Side Note: It will not hurt if you resolder connections which you think are still good. It is better to resolder and make sure you did it right than only fixing a few and hoping that it works. 

Step 10: Testing

Picture of Testing

If you believe that you have fixed all of the cold solder joints, you can now proceed to replacing the core components and testing the monitor. To do this, you must follow your notes that you took while disassembling the monitor, to reassemble it. To make the tests, all you need to replace is the plastic part which prevents short circuiting components, re-install the power board, and plug the back light cables back in to their correct spot. From here, you can plug the power cable into the monitor to see if it powers up and stays on. 

If the test fails: repeat step 9. If step 10 does not bring positive results after performing step 9, 3 times, chances are, there is a different problem which is not being covered by this Instructable.

Helpful tips:
 - Remember to replace the protective coverings which prevent short circuiting and damage to components
 - You do not need to completely reassemble your monitor to make tests
 

Step 11: Putting the Monitor Back Together

Picture of Putting the Monitor Back Together

If step 10 is successful, you can now begin to put back your now working monitor back together. To do this, simply follow the notes that you took in reverse order. Make sure that you replace all the components and shields. These are essential to the safety and work-ability of the monitor. Every component that was pried/snapped off, can be easily re-snapped in place. 

Step 12: Conclusion

Picture of Conclusion

Congratulations!!! You have successfully repaired your monitor on your own and saved yourself a lot of money! I hope that these instructions successfully led you to a working monitor. Additionally, I hope that you have gained knowledge about how a monitor is made and what components allow you to see what you are doing on your computer. Please leave any comments so I can actively improve upon this Instructable. 

Thank you

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