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about today's article on repairing the CMV 19 "LCD Monitor problems model CM-922D. The complaint had no power as what the client told me. This power supply has not been built into the circuit so it takes external power adapter to power up. The entrance to the LCD screen is 3.1 amps 19V adapter. Since the complaint had no power, we must be tested to see if the adapter is at fault or the LCD.

The AC power was connected to the adapter and I could see the power light was lit. Checking the output voltage of the adapter I have about 19 volts which is good. Even if the light is on and correct the output voltage, this does not mean that the adapter can maintain when there is a charge (LCD) connected to it. I once came across a Compaq Monitor 17 "LCD with a precise output voltage of the AC adapter, but when connected to the screen, the screen appears for a split second before s extinguish. Usually, in this case, your experience will tell you it could be the inverter circuit are faulty or the lamps have problem. You would be surprised to see that the real cause of the shutdown was due to the adapter. It can not withstand the output voltage when there is a charge on it.

This type of fault is normally due to bad filter capacitors located at the exit of the secondary circuit. If you have ESR meter, you can quickly identify defects electrolytic capacitors. If you do not count, just a direct replacement plugs. As mentioned in my previous repair to confirm whether the adapter is really working or not you need a bulb to act as a burden. Make sure the power light does not flash when the bulb is connected. Even if it flashes once, this proves that regulation is not good and should be verified completely. In China the above is LCD monitor, the adapter work perfectly!

As I have already confirmed that the adapter is good, I'm concentrating now on the LCD boards. Removing this cover was very easy and you can easily access the card when the metal casing was removed. The first thing I checked was the fuse SMD located in the main board. If the fuse opens then there would be no offer to ADC / Scalar and IC and CPU power LED would not light! Checking this SMD fuse was rather simple as the control method is the same as a normal fuse. Use either analog or digital range of a meter value ohms or continuity check. You can check the fuse while it is still in the circuit. Yes, the fuse was found at open circuit.

Now there is a question that must be answered by us. What makes the fuse to go open circuit? Well from what we have known about electronic repair, there are three possibilities that this opens a fuse circuit. First, the fuse can become open circuit due to its life. Some fuses can last for many years while some couple of years. In other words, the life of a fuse depends on the quality of materials used. Secondly, the external factor such as a surge causing the fuse to open circuit to protect the main board. Thirdly, the motherboard itself problem (as a short-circuit IC and other electronic components) which caused the fuse to open circuit.

If the LCD monitor problems lies in the first and second category, then replace the fuse will certainly solve the problem. However, for LCD Monitor, replacing only the fuse does not work at all and the fuse open circuit again. You have only two choices to solve this problem. First, you can use a regulated external power supply, as explained in my previous repair articles and connect the negative output of power to the ground and the positive and the fuse (the line that leads to other circuits) to detect short-circuit. Slowly vary the outpu.