TRANSISTOR OVERHEATING

Discussion in 'General Electronics Chat' started by misael.mata, Sep 11, 2014.

  1. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    0
    IM HAVING ISSUES WITH MY AUDIO AMPLIFIER, TRANSISTORS HEAT UP WITH NO LOAD, WHAT COULD CAUSE THIS, ANY HELP IS APRECIATED, THANK YOU
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
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    Hello,

    Post your schematic, sso we can see how things are done in your circuit.

    Bertus
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,973
    3,219
    If the output bias current for a class AB is too high (for whatever reason), then the output transistors will overheat.
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    if the amp seems to work, check the bypass caps on the emitters of the output stage. if leaky or shorted that will mess up the bias and increase the current.
     
  5. flat5

    Active Member

    Nov 13, 2008
    403
    17
    There may be an oscillation.
    Do you have a voltmeter to connect to the speakers one channel at a time?
    Check for DC AND AC voltage.
    With the volume at minimum the meter should measure very close to zero volts.
    Checking with a 'scope would be even better.
     
  6. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    0
    I allready replaced the bad caps, voltage is good on channel, i also replaced bad transistor fets, and they still heat up, i cant find a schematic for this amplifier but its a memphis 16 pb1kd
     
  7. misael.mata

    Thread Starter Member

    Aug 26, 2014
    55
    0
    what else could cause this so i can keep checking them one by one. i appreciate all help.
     
  8. bertus

    Administrator

    Apr 5, 2008
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  9. ScottWang

    Moderator

    Aug 23, 2012
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    You have to take some photos for different angels and attach them.
     
  10. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    0
  11. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    this is before i replaces the parts, the gate resistors are the big green ones? they should read .1 ohms, (black brown silver gold) some read 0.0 ohms, is this bad..... thank yall
     
  12. bertus

    Administrator

    Apr 5, 2008
    15,638
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    Hello,

    On that DIY forum they are talking about SMD resistors.
    These are small black or gray looking rectangular blocks.

    Bertus
     
  13. misael.mata

    Thread Starter Member

    Aug 26, 2014
    55
    0
    Is there a specific website where I can look up amplifier schematics, I can't seem to find any. Thanks for responding
     
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