The client grievance of this Sharp LCD LL-T15G2 LCD Monitor was no power within the power adapter and LCD screen. The moment I detached the casing I saw the interior cowl and therefore the power provide board had burnt mark thereon. First i assumed it absolutely was hit by lightning however upon fastidiously examine the board I found that the yellow wire was touching one in every of the bridge rectifier diodes pin.
You could conjointly clearly see that one a part of the track had broken. Surprisingly the fuse didn’t open circuit! The darken board ought to be clean with agent answer before I begin getting down to check on the suspected parts. First check that the filter condenser haven’t any voltage checked with the assistance of your meter, if there’s voltage you’ll discharge it with a two.2 k ohm
10 watt resistor place across the capacitor leads. This is just a normal procedure as I don’t want any of my readers who are new in this field to get discharge through his body from the capacitor charge.
Once I have confirmed that there are no more voltage in the filter capacitor, I will then use my analogue meter set to x1 ohms to test on the power FET (part number is 2sk3114). Place the black probe to the centre pin of power FET and the red probe to the other two pins one at a time. The meter should not register any reading, if there are readings; it could be the power FET has shorted. In order to verify it the simplest means is to get rid of the field-effect transistor from circuit and check it.
If the ability field-effect transistor did not blow, probabilities is incredibly high the heart beat breadth modulation IC (PWM) KA3842B is sweet. The resistors within the primary facet checked to be okay too.
After this take a look at i will be able to use the Dick Smith flyback tester to position across the ability electrical device coil to check if the winding is shorted or not. The readout was eight full bars and this proves that not solely the first winding is okay, the secondary diodes as well.
If either the first winding or the secondary diode shorted, the meter readout would drop to very low or totally goes off. Now, i might simply scan all the electrolytic capacitors with my ESR meter though I knew that the possibilities for the capacitors to travel unhealthy is incredibly slim thanks to the problem was short circuit between the yellow wire and one of the bridge diodes and it definitely would not affect the capacitors.
Okay coming back to the bridge diodes, samsung tv repair london always check the diodes while it still on boards with (your) analogue meter set to x1 ohm. It should not register two similar readings. If you’re undecided concerning the reading you’ll invariably compare with the opposite diodes.
Checking the diodes on board I found one to be defective and that i removed all of them and replaced with four new 1N4007 diodes. For your data, if one of the diodes shorted or opens circuit, one has to replace the other 3 diodes as well. I don’t understand you, but from my years of electronic repair experienced, I do came across problem where after sending back the equipment (after replacing one of the For reliability reason and to prevent the customer from sending back the equipment for warranty claim, the best is to replace all of them if found one diode to be faulty.
This diode isn’t overpriced compare to the time loss associate degreed it should have an effect on your name too as an electronic fixer. After the replacement of the new diodes, you wish to hitch back the broken track with the assistance of a lead cut from a two watt resistance. Before you turn on the ability provide, one should always connect a a hundred watt light-weight bulb to check.
The reason for using the light bulb is to prevent the power supply components that you have just replaced to blow again just in case if there is short circuit somewhere within the power provide that you just have incomprehensible to envision. Simply take away the fuse and connect the 2 wires of the sunshine bulb across it.
Now start the ability provide and observe the sunshine bulb. If the bulb lit brilliantly and stays there for an extended time, this means that there are still problems in the power supply.
When I plug the twelve potential unit jack to the LCD Monitor, there was no power. I presumed the short circuit in the power pack/adapter may have caused the LCD internal fuse to blow as well.
True enough, once gap up the LCD cowl and check on the fuse, it found to be circuit. Solving the internal fuse and the power supply problem put the Sharp LCD Monitor back to life again.
Not solely you gained the satisfaction from repairing the ability provide, you get paid conjointly from your customers too! That’s all for it, take care my friend.