Hello again my dear friendsWe are back with another video more From electronics Núñez tutorialsAs you can see I have a screen here From the LG brand, this screen is a plasmascreen Which is the model 42PA4500This is the model of this TV And this screen gentlemen is representingThe typical protection failure I will connect it to the electrical networkAnd you can appreciate that I have the stand by activated correctlyBy pressing the power on key we see the stand by ledIt turns off but the TV does not turn on, Very good how you can see that is all thatthe TV does.
This gentlemen this lets us know that thisscreen has a failure of Protection, and in this video tutorial, theyWe will teach step by step how we are going toSolve the fault, on this television LG brand plasma screen, but you have subscribedthe channel I invite you to do it And that you activate the notification belland so you can have a Message every time we upload a new tutorialI also invite you to like my videos and That I can share it in your social networksand so, well let's help the Rest of the technical community in differentcountries of this planet.
Ok, and we're going to make this channel biggerand we We are going to feel much more motivated tocontinue climbing more Information that will be very useful for you, when facing different Failures in the televisions of the new generation.
Very good gentlemen then I will proceed todisarm it Then we continue with the tutorialVery good how can you watch here we have uncovered the TVAnd what we mainly have to analyze in a fault like this, It is to verify if the power source is working correctlyThis is done by checking the output voltages to the MAIN cardAnd in the same way the power voltages for The SUS cards.
If you do not know how to check this powersource There in the channel they left a tutorialwhere he taught the techniques that can be Apply to check them externally, Now in these cases regarding the failure that we have in this TVWhat we have to totally discard is this that thePower source is working and the MAIN card is in good conditionAlright, then there is a very simple technique that can be appliedGiven that in this type of televisions, what most commonly fails are theYsus cards and Xsus card then what we are going to do is, Disconnect the power cable for the SUS cards Here as you can see we have left only thecable Power to the MAIN card, now let's connectit to the network.
Let's press the power on key.
And how can you hear that now when you connectit you can hear audio, Which means that the power source is emittingcorrectly The power voltages for the Main card.
The MAIN card isThen it is working, very well It means then that if we connect the powercable for the SUS cards Then the TV goes into protection and the TVdoes not turn on.
So now what we're going to do is check theoutput voltage For SUS cards, In this part of the book, what are the Voltages that have to go out for those cards.
As you can see hereHere I am indicating the output voltages for these cardsLet's see we have the voltage VS we have here this area where it says it is not emptyHere negative the voltage VA and the voltage of 5 voltsNow to analyze what amount of voltage has to go out? This information is in the stickerWhich is around here, which is indicating the voltage of 5 voltsIt is indicating the VA voltage of 55 volts and the VS voltage of 205 volts.
These are the voltages that we have to checkif they are present in the source, Okay, now let's take a reading of those voltagesWe are going to use our millimeter in DC current and let's take negative groundchassis from anywhere Metallic screen.
Ok here I have 5 volts, Here I have 54.
6 voltsand I have 204.
9 By picking up this reading it means then thatthe source of power is in perfect condition, She is correctly issuing the voltage for theSUS cards, Now what I'm going to do next him next.
I'm going to disconnect the voltage supplyfor the YSUS card I'll connect this again, and I'll check ifthe TV turns on, With this I would be ruling out that thiscard is causing the breakdown.
Very well already press the power on key andif there is audio, Which means that the tv turned on correctly, and this It tells us that this card is not what iscausing the breakdown.
So, in conclusion, it is this YSUS card thatis damaged.
Commonly in this type of cards what is damagedare mosfet, Power, and in this case the type of IGBT mosfet.
We will have to disassemble this card to beable to check The status of these MOSFETs, I will proceed to remove it.
Ok how can you see that we have the YSUS carddisconnected, We have here what is the whole circuit.
This type of cards gentlemen is a little complicated to prepare them, Since, on many occasions, all are burned The mosfet, then also on this side we havesome Rectifier diodes that also burnEven down here we can also save another IGBT mosfet, That also are the ones that are damaged when breakdowns ariseIn some of these components, Ok and here with respect to the protectionresistors, As the case of the resistances of 0.
22 homsHere we have another one of 0.
22 homs These are the ones that are commonly damaged, causing more breakdowns, To the rest of the mosfet, which are in the amplificationsystem.
Now as we talk about they are high power mosfetThen we can check them, but for that it is necessary, Remove them from the card ok.
In addition to this there is much also toknow about this type of cards Since many times we replace the mosfet andit happens that, When we connect again theCard to do the test on the TV and immediately They burn again, ok.
I think that many of us have played like this, So what we have to do also when we replace the mosfet, Or the IGBT that carries this type of card, It is also necessary to check the status ofThe capacitor mainly capacitor this because it many operationsThis is responsible because the mosfet are burning.
Other matters that must be takenIn account at the time of finding damaged IGBT are the oscillators, Since if any of them is not working correctly The mosfet is not going to activate so itis going to burn, Then it is necessary that we check.
the state of the oscillators.
If you do not know how to check these typesof oscillators, then wait later, In a tutorial I will show you some techniquesthat can be applied, for Be assured that oscillators are not the causeof the problem, or at least That the mosfet will not be burned again, because of oscillator problems.
Along with this also remember that it is necessaryto review the status of Protection resistors and check For the fusesof course they are in Good condition Now to check the IGBTs is quitesimple, We will use an analog multimeter, and thiswe will use the scale X1, we are going to verify here, mainly weare going to check if.
OkayNow with regard to checking the status of the mosfet, Well mainly what we have to verify is that there is no unionThat is, they are not crossed.
As you can definitely see this mosfet is crossedor united, We have the rectifier here because it is alsomarking together.
Because of the problem we have in the firstIGBT, We will try the second one, because if youcan appreciate it also because it is marking, That is in short circuit.
It does not necessarily mean that both areburned If not then it will be necessary to raiseone by one to find which of them is damaged.
We have here these other mosfet that are onthis side, observe the measure that I have here.
It is marking as seven homs, by invertingthe tips as it is not I would have to measure, however, if it ismeasuring, the same.
This may also be because these other mosfetcan be short circuited.
We're going to have to get up to get out ofthat doubt.
I have this other mosfet here and it definitelyalso looks like it's crossed And this other one that I have here is alsocrossed.
I have here the diode and how you can seeit is completely crossed On this side it is also necessary to checkthe state of the mosfet, Diodes and the GBT that is on this side isa 30f124, The way to test them is the same as the otherarea that we already checked.
We are going to verify with a tip the leg of the center and we are going to Check the other pins, and if you can appreciatewith just this, be measuring Both sides are telling us why they are shortcircuited.
As you can see on this card all the mosfetare marking that they are in Short circuitWe will start then mainly removing the mosfet that are here.
These are the cargo mosfet these are the onesthat are mainly damaged.
So we are going to raise one by one and thusverify which of them, because they are the That are broken.
And in the same way we are going to checkthe mosfet and the IGBT that is here, Let's check the resistance as I mentioned.
And let's check if the oscillators are notshorted.
Well I will proceed then we continueWith the tutorial.
Very good after having reviewed all the mosfetand the IGBT As I find these are completely short.
I also find this other mosfet that is hereIn the same way in short circuit, Already what is crossed that was here hasalready disappeared, After that, he has also checked the resistances, I have checked the oscillators, And they are in perfect condition.
Apparently, we only replaced these componentsand the card is already Ready to do the corresponding test.
Now to replace that type of mosfet or theseIGBT, This is the RJP30H2A code, I have this otherRJP632K and I have this other one here which is, KF7N60Ok to replace those IGBT and those mosfet, because I'm going to use the ones in thisrecycling card, Since most of the components that we are buyingin the service stores are of low quality And immediately you install the test and reheatand burn, For that reason I prefer to use recyclingtransistors because I know they are of higher quality, Ok then I will proceed to extract here the spare parts to install them, And then do the corresponding test.
On the screen.
Very well how can you observe we have alreadyconnected it, All the cards are connected correctlyand there you can hear apparently the TV already turned on.
I'm going to revolt him here.
Very well how can you appreciate we have rainalready we have video signal Now it was just going to connect with the antenna signal to verify how we Present the image[Music] Very good and it is, let's change channelhere, this is analog signal Okay, that's how you can appreciate the imageIt is excellent, the television gentlemen has been properly repaired.
All right, gentlemen, this is another video from electronics Núñez tutorials Remember to subscribe like and share my videos.
See you until the next tutorial.