Question about MOSFET replacment

Discussion in 'General Electronics Chat' started by rthexton, Dec 4, 2008.

  1. rthexton

    Thread Starter New Member

    Sep 8, 2008
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    Hi guys, im new to electronics and i am attempting my first repair job, I have a car amplifier with a blown tranisistor in it. My question is do you need to use exactly the same brand transistor in the circuit or can i use another brand. I am guessing if the specs are the same this should be OK but i am not really sure what key specs to look out for. The tranisitor that is blown is a Fairchild FQP50N06, unfourtantley i cannot purchase this part locally, i had found one that seems similar but i would like verfication if they are the same. Please find attached the data sheets for the Fairchild and the other one that seems similiar. Cheers
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    From a quick look at the datasheets it seems you can replace it. I noticed they have a bit different transfer graph (how Id changes with Vgs) but it will be ok if it is used as a switch (class D amplifier). Also, if it is used in its linear region as in an analogue amplifier then it will fine due to the negative feedback amplifier implement.
     
  3. rthexton

    Thread Starter New Member

    Sep 8, 2008
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    mik3 thank you very much for your help, it is a class D amplifier. Its a monoblock power amp ,You have saved me allot of time. Cheers!
     
  4. rthexton

    Thread Starter New Member

    Sep 8, 2008
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    Can someone advise if this is the same as the two above the Rds is lower 0.018, and it has a different lower power rating. Will this make any difference??

    Cheers!
     
  5. mik3

    Senior Member

    Feb 4, 2008
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    If you are talking about the STPB55NF06, its on the limit. If you are talking about STPB55NF06FP no. Its power rating is much below of the previous ones. Maybe it will be ok because its a switching application and it consumes little power but I don't think the designers were so stupid to put transistors with such a higher power rating.
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    One thing I forgot to mention is that if the MOS to be replaced is in parallel with another one then this may cause problems. To parallel two MOS they have to be identical.
     
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