LCD TV/Monitor Repair Do-it-Yourself Guide

LCD Monitor Power Supply Repair Tip

Diagnosing and troubleshooting the LCD monitor power supply pack is quite easier than diagnosing and troubleshooting that of the CRT monitor. They are more compact and are smaller and they generally have just one output which is 12 volt and range between 2 to 4 amperes. There are some designs that uses 18 and 24 volts. Today, most LCD monitor power packs are built right onto the main board like in the Dell E151FP LCD monitor. Older LCD monitors have their power supplies as separate power pack modules.

The power pack module type is simpler to troubleshoot because you can just replace it working unit isolate if it is really the power pack that is faulty. You could likewise use a DC external power supply to power up the monitor to diagnose if it is really the power pack.

Now, If you do not have an external DC power supply to use, you can just use the following method to ascertain the problem especially for cases of no power, low power and power blinks: Connect a 12-volt light bulb (like the bulbs used in rear lights of cars), to the power pack output jack. If the bulb is lit up brightly then there is nothing wrong with the power pack. If it blinks or dims up, then the power pack has a problem.

From previous experience, most LCD monitor power supply problems, whether in the power pack or built into main board, are usually due to the failure of electrolytic capacitors (most probably caused by overheating) in the primary and secondary sections of the board. Most of the capacitors will have a high ESR readings which produce low power supply output, cause power blinks or complete power outage. The typical values of electrolytic capacitors in the primary side are 47 and 100 micro farad 50 Volt. The secondary sides are about 1000 to 2200 micro farad 25 volt. On occasions you will see the capacitor’s top casing bulge out and the sleeve that covers the capacitor casing would be brownish. The capacitors are busted.

The power supply section in some LCD monitors still use the UC3842 pulse width modulation (pwm) IC. Replacement for this kind of IC’s are easier to find than other power IC’s. One example would be the Samsung 153V LCD monitor which uses the TOP247F power IC which is easy to diagnose when it is not powering up properly.

Diagnosing and the LCD monitor power pack/supply is not that hard if you have a little understanding of how the power supply works.

Guest author of this article is an electronic repair guru by the name Jestine Yong. He has an lcd monitor repair training e-book which you may want to check out to learn more about electronics repair. To find out more, please go to this lcd monitor repair course website.

Related site that you might be interested in: lcd tv repair course

LCD TV Repair Tips

Samsung LCD TV

This LCD TV troubleshooting article was written by Steve Faber of What is the Best LCD TV Guide

There are a ton of reasons why you could be having technical problems with your LCD flat screen TV. The important thing to remember is that these contraptions are microprocessor based, much like your laptop or your desktop PC. That means that at the first sign of abnormal function or operation you should do exactly as you do with your PC: Reboot!

If your LCD television is being non-responsive, switch it off properly (with the power button), count to 10, unplug it from the wall socket, then after about 60 seconds, plug it back into the power socket and turn the TV back on again. With a lot of luck, your TV is now back to normal!

The next possible cause of problems that you should look into when experiencing problems is the High-Definition Multimedia Interface (HDMI) connection. HDMI is a great way to get high definition video fidelity, but it is so good that the content providers were worried their stuff would end up out on the internet, easy to copy and distribute. To prevent such piracy, they created this copy protection plan called High Density Copy Protection (HDCP); which is much like an electronic data handshake system wherein the source and display devices (the televisions) have to recognize each other and agree that it is okay to send video. If there is no handshake, or the process gets corrupted in some way, then there you go: No video. This problem, although revalent in the younger days of HDMI, has been steadily improving in very recent years due to better technology.

If you are having LCD TV problems, there is a chance that it may be an HDMI related issue. Here are some of the problems you might encounter and what you need to do:

Problem #1: No Picture

If there’s absolutely nothing on the screen then shut the television down and then restart it. Make sure all the connections are properly placed and where they should be. Look at the screen. If you see a resolution notice or indication then chances are that the Display Data Channel (DDC) line has communicated between source and sink. This means that the problem is likely video related.

Problem #2: No Audio, Flashes, Pink Screen

If there is no audio output accompanied by a pink screen, it might be a DDC communication error or problem. To diagnose this, turn the system on while all the HDMI cables are plugged and properly connected. When possible, try using shorter cables. If the system still fails to come on when you power up, try using different inputs. You might find that your cable box will work but your DVD may not or vice versa. This can happen because of stray capacitance on the DDC line inside the HDMI cable. This may actually be hardware related. Try getting a DDC line conditioner. These types of problems completely go away after conditioning.

Problem #3: Sparkles on the screen/picture

This is usually data transmission-related problem. Data transmission problems with HDMI are usually cable-related. There is a possibility that the cable is underperforming due to excessive length. This is especially common problem with cheap, sub-standard cables. Remember the HDMI specification indicates that the cable length should not be more than 10 meters. Shortening the cable should improve the signal integrity. Another possible scenario in this situation is a bad connector. HDMI connectors are famous for this very common.Try a new cable at each position along the signal path.

Problem #4: Picture on the Screen Comes On, Then Goes Off

This is usually caused by a couple of things. First is when one or more of the video Transition Minimized Differential Signaling (TMDS) channels has a high bit error rate or is not working at all. Second is when the DDC line does not quite make it. In that case, the High-Bandwidth Digital Content Protection (HDCP) is not getting a new refresh key. Buy a better quality cable with larger wires. When it comes to wire gauge, smaller gauge equals bigger wire diameter. Hence 20 gauge is larger in diameter than 24 gauge.

If you are having some LCD TV issues, check these things before you call the expensive TV repair guys. In many cases you can easily repair LCD TV yourself without spending a fortune.

More info about how you can troubleshoot and diagnose your TV at LCD Television Repair