I am searching one model transistor from monitor "keys board"

Discussion in 'General Electronics Chat' started by UnnamedUser159, Jun 30, 2016.

  1. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
    The LCD is l17mp-p

    the board is lxx30 key

    i am searching the model of Q2 because it`s missing.

    Transistor x for replacement also is fine.
     
  2. EM Fields

    Member

    Jun 8, 2016
    167
    28
    That's like searching for a needle in a haystack when there's no needle there...
     
  3. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    A picture of the board might help us guess. One thing to keep in mind is that just because a component has a footprint (a place) on the board, doesn't mean that it should be there. Sometimes there are things that are intentionally not loaded, and would mess up the board if they were just put in.

    If you know that the transistor was supposed to be there, like it burned in service, then there will a much larger debugging problem. Generally not worth fixing that situation, but some folks on this forum have done it.
     
  4. UnnamedUser159

    Thread Starter Member

    May 3, 2016
    130
    0
  5. ElectronicMotor

    Member

    May 1, 2016
    53
    6
    It is very common for manufacturers to design a circuit that will function differently when certain components are removed, depending on the market and the system it is designed to go into.
     
  6. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    Looking at the picture, the transistor may be for driving the LED(s). If you can read the markings on Q1, then Q2 is almost certainly the same thing. If you can't read the markings try testing Q1 with an ohmmeter to determine whether it is NPN. If it is, a good guess would be MMBT3904. An LED driver is not very sensitive to transistor type - any general purpose NPN transistor would do, as long as the pinout matches.
     
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