transistor markings question

[NOOBNOOB37]

Hello to all of you in this forum. I have found so many useful things here, from various info to excellent tutorials that helped a newbie like me to fix some simple electronics..
So,  first of all, let me express my gratitude to this forum and all its members.

I am in NO WAY an electronics expert (not even studied any stuff like this). But many times i have stumbled upon "broken" electronics that need fixing (like replacing some tact-switches in my synthesizer, replacing capacitors, resistors, or constructing a pcb with various components based on other peoples' instructions etc..)
So, now, a new problem arised : my plasma tv has gone black, and based on various stuff i read in the web, it would probably be the YSUS boards' fault.. So i tried to check some electronics components with a multimeter, and found some transistors shorted to ground, and maybe a PP capacitor is leaking ...

Unfortunately, the transistors have some markings i cannot translate to actual specification, and i really need your help in this. There you go:
(transistors with 3 legs THROUGH-HOLE, probably TO-220 or TO-220F packaging, if i say this correctly..):
1)  (1rst line)  0944 /  (2nd line)  F20LC30
2)  1942  /  F20LC30
3)  0544/  F20LC30
4)  0644/  F20LC30

(Transistor SMD with 3 legs (one not to be soldered) and a tab on the opposite side) :
N 4C / 61FC4

I really do NOT have a clue if these are MOSFETs or diodes or regulators. I only found datasheets for the F20LC30 but i cannot identify the numbers before this code, so i am not sure if i should buy any F20LC30 with different numbers..

I would greatly appreciate your help with this.. (please note that my electronics knowledge is quite limited, so be gentle    )

Greetings from Greece!
   
     

[magic]

The TO220 thing may be a dual diode

https://ae01.alicdn.com/kf/HTB199sTw7CWBuNjy0Faq6xUlXXa5.jpg

[TimFox]

For numbers 1) to 4), the four-digit codes are probably date codes:  0944 is 44th week of 2009, 1942 is 42nd week of 2019, 0544 is 44th week of 2005, and 0644 is 44th week of 2006.  That company is busy in the 42nd and 44th weeks!
Datasheet  for F20LC30 dual diode:  https://datasheetspdf.com/pdf-file/808038/Shindengen/F20LC30/1
There are several websites that link to datasheets:  I usually google the part number and "datasheet" to find them.

[NOOBNOOB37]

The TO220 thing may be a dual diode

https://ae01.alicdn.com/kf/HTB199sTw7CWBuNjy0Faq6xUlXXa5.jpg

Thanks magic for the info. And yes, the transistor is like this but with different numbers in the 1rst line of coding... I already found some in ebay, from China. But i can't figure out what the 1rst line numbers stand for..

[TimFox]

See my reply above about date codes on the first line.

[NOOBNOOB37]

For numbers 1) to 4), the four-digit codes are probably date codes:  0944 is 44th week of 2009, 1942 is 42nd week of 2019, 0544 is 44th week of 2005, and 0644 is 44th week of 2006.  That company is busy in the 42nd and 44th weeks!
Datasheet  for F20LC30 dual diode:  https://datasheetspdf.com/pdf-file/808038/Shindengen/F20LC30/1
There are several websites that link to datasheets:  I usually google the part number and "datasheet" to find them.

Thanks TimFox for the information. So it adds up this way, that the manufacturer uses the same part x-times in the same board (the 0944 & 1942 are a apir , and so are the 0544 & 0644. Thanks also for the datsheet link , this is exactly what i found by typing the part nr in google..
So, as magic said, these seem to be diodes, right? Is it safe to say that the only important code that describes the transistor is the F20LC30, and i should use this for the new replacement, correct?

[NOOBNOOB37]

And what about the N 4C / 61FC4 ? Looks like a N-MOSFET ??

[TimFox]

Yes, if your physical part is that shown in the data sheet to which I posted the link.

[NOOBNOOB37]

I actually do understand you as I have registered here just in order to find out many new info available here, maybe sharing some feedback))

Oh yes, i agree, sharing knowledge is the best offer people make in these forums. And sharing makes a world a better place.

[NOOBNOOB37]

Yes, if your physical part is that shown in the data sheet to which I posted the link.

Yes, the physical part is exactly like the one in the datasheet you posted.

[TimFox]

If you Google “61FC4 transistor datasheet”, you will find the manufacturer and distribution.
The date code is from the semiconductor manufacturer, and the system manufacturer does not specify the date code, only the part number (61FC4 or F20LC30).

[NOOBNOOB37]

If you Google “61FC4 transistor datasheet”, you will find the manufacturer and distribution.
The date code is from the semiconductor manufacturer, and the system manufacturer does not specify the date code, only the part number (61FC4 or F20LC30).

Found this https://www.veswin.com/product-61FC4.html .
Also this ebay post https://www.ebay.com/itm/10PCS-61FC4-TO-252/302979565611?hash=item468afd482b:g:ApMAAOSwTxJcAnpt .
So, you say that the same applies here : the N4C is the manufacturer coding (date etc) and the chip description is 61FC4, correct?

[NOOBNOOB37]

Oh, and something i noted in your explanation of the date codes, TimFox : the dates of the chips don't add up : the PCB was manufactured before 2004, how is it possible that the transistors have a later date (p.e. 1942 = 42nd week of 2019 ...). Perhaps the fIrst line coding is something different than the mfg date ??

[TimFox]

That is a common format for date code, but it could mean something else.
Are you sure of the manufacturing date for the TV?

[NOOBNOOB37]

The tv is LG RZ-42PX11, and it was purchased by my father in law in 2004 and i got it  in 2015. So perhaps it's not a date code? It would make sense, though (would be easier for me, so i would go and buy those chips in ebay right away!). But, now i am curious and wanna know what that code means !!  

[NOOBNOOB37]

Any updated information, please ?

[m3vuv]

why not buy a cheap chinese component tester,i have one,its great for this sort of thing,falls over at 78 seriries voltage regulators tho,but for most thru hole transistors,diodes caps etg,its a must have,gives you the hfe pinouts etc,just get yourself one,you will never look back!!

[NOOBNOOB37]

why not buy a cheap chinese component tester,i have one,its great for this sort of thing,falls over at 78 seriries voltage regulators tho,but for most thru hole transistors,diodes caps etg,its a must have,gives you the hfe pinouts etc,just get yourself one,you will never look back!!

Thanks for your suggestion. You mean a tester like this :  https://www.ebay.com/itm/Multifunction-Tester-Transistor-Diodes-Decoder-Electronic-Component-Household/224112379958?hash=item342e238836%3Ag%3AU3IAAOSwq%7EBdr-e3&LH_ItemCondition=3
or this https://www.ebay.com/itm/LCR-TC1-Transistor-Tester-ESR-Capacitance-Meter-Electronic-Component-NPN-PNP/402282387770?hash=item5da9e6193a%3Ag%3A4ZUAAOSw5BNeeaux&LH_ItemCondition=3
?
i assume that the components must be removed from the board in order to test them, right? I only used a multimeter to check for shorts, that is my knowledge limit...

But should i know first the specs of the components (p.e. transistor), before i get the tester? I guess the datasheets are useful here, correct? So, i think that first i should identify the component and then proceed, is this right?

Sorry if my questions might sound naïve to you, but my knowledge is quite limited.. (please don't  )