Don't Miss

Finding Transistor Specification

By on July 24, 2010


Sometimes i really do not understand why the semiconductor manufacturers do not print out the full part number at the transistor front casing and left out few alphabet and give us hard time in locating the data/spec? Many times without the first few alphabet in the part number, you will not be able to locate the datasheet especially from the semiconductor databook. For example, this part number P3NK90Z which is the power FET located in the switch mode power supply actually is STP3NK90Z. You can see the part details here. If you look for P3NK90Z from the databook then you will not be able to locate the spec. However, this part number can be locate from the internet.

My concern is that what if there are other type of part number that you can’t locate from databook or internet just because of some missing alphabet in the part number?  You have to be sensitive about this part number thing otherwise you will be wasting time finding a part number that does not exist in databook or internet. Why is it so difficult for the manufacturers to print the full part number? This has to be answered by the manufacturers itself. If you have the answer, we would like to hear from you.



  1. Russ

    July 24, 2010 at 5:46 pm

    What about IR LED's? They have no letters or numbers or anything that helps you determine what the spec's are. I come across them in my service of redemption and other coin op games. I needed to replace four of them the other day and they wanted $55.00 for it. They wouldn't tell me what part number it was so I am going to try and buy a bunch of them off eBay and swap them in hoping that one will work. Any ideas or suggestions?

  2. beh

    July 25, 2010 at 11:44 pm

    the answer from manufactures:
    this purposely is done on all of our prouducts to stop all repairer
    from thier jobs . and encourage the useres to buy always new sets not
    to repair them.

    TOSHIBA . PANASONIC. SONY.ALL CHINES BRANDS ..SO AND SO......................................................

  3. admin

    July 26, 2010 at 7:53 am

    Hi Beh,

    Thanks for sharing and i hope they don't mean it that way. The manufacturers can always remove the part number as what i have seen on a brand of UPS and there is no way, any repair tech could know what the part numbers were.


  4. admin

    July 27, 2010 at 8:21 am

    HI RUSS,

    Sorry no info on this and i guess the best is to ask the staff from electronics shop on how to see the different especially the part number. Not long ago i opened the remote control and found 3 IR LED and the measurement was different from the normal LED.It does not have reading even using the analog meter.


  5. Shahidan

    May 7, 2013 at 4:08 pm

    It is quite common for manufacturers do not print out the first two alphabets of a transistor. hey assumed that the alphabets are redundant . Transistor C945 is 2sc945. The P in your examples denotes that they are in plastic casing. Those transistors with markings P....are normally recognized as STP...Tell me if I am wrong.

    • Jestine Yong

      May 7, 2013 at 4:21 pm

      Hi Shahidan,

      Not sure if the letter "P' is denotes as plastic casing or insulated but what i know some manufacturers just remove the few front letters making tracing the original parts difficult.



Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.