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General electronics => Beginners => Topic started by: NOOBPASTE51 on December 01, 2020, 12:02:19 PM

Title: transistor markings question
Post by: NOOBPASTE51 on December 01, 2020, 12:02:19 PM
Hello to all of you in this forum. I have found so many useful things here, 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   :-[ )
Title: Re: transistor markings question
Post by: davekni on December 01, 2020, 07:39:48 PM
If you've found a part "F20LC30", then the other numbers may just be lot numbers and/or date codes.
Title: Re: transistor markings question
Post by: Arcatarter on December 24, 2020, 12:17:37 AM
I have come across this issue many times while scavenging parts from plasma TVs, many of them have parts which I have been unable to find datasheets for. However I do know that all of the plasma TVs I've seen use IGBTs and rectifiers, and those are typically the components which I am unable to find datasheets for.

The majority of the plasma TV circuit boards I have use IGBTs that are rated for 300 volts and around 80 amps, and the rectifiers are usually around 400 volts and 10 amps. I feel pretty certain that the part number you gave is an IGBT. If pin 1 has a smaller trace than pin 2 and 3, you can be almost certain that it is an IGBT as the gate (pin 1) will almost always have a small trace due to the much lower current required. If you can take pictures of the board, I could tell you almost for sure whether they are IGBTs or rectifiers.

The numbers around the f20lc30 aren't important, as davekni said they are likely lot numbers and date codes.
Title: Re: transistor markings question
Post by: Mads Barnkob on December 24, 2020, 10:01:17 AM
When searching for part numbers from power silicon components, I find it useful to only search for the two numbers and the letters in-between. They are almost always structured as current first, some letter and then voltage rating. 20LC30 would be 20A 300V and LC is manufacturer specific.

As seen here: https://www.alldatasheet.net/view_datasheet.jsp?Searchword=20LC30&sField=3

The prefix of S, DF or SF makes a difference if its a diode or MOSFET, so that is how Shindengen chose to name their devices with a common current/voltage part of the name across different types.
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