Amplifier circuit trouble

Discussion in 'General Electronics Chat' started by misael.mata, Aug 26, 2014.

  1. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    im new here and i know somewhat about how amplifiers work, but im working on one right now and still cant diagnose why one channel of the amp crackles and sometimes dead:confused:
     
  2. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    please help
     
  3. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    I have a memphis amplifier that makes a crackling sound only on one channel, why is this happening, i have already checked everything, and everything looks okay, im new here
     
  4. wayneh

    Expert

    Sep 9, 2010
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    When you say "everything", has that included the speakers; have you tried swapping channels?
     
  5. to3metalcan

    Member

    Jul 20, 2014
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    Specific make and model? Any schematics, etc.?

    Does it make the cracking when the amp is idling, or when you adjust the volume? Does it start immediately, or after warming up?
     
  6. to3metalcan

    Member

    Jul 20, 2014
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    I think you have duplicate threads...
     
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  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Clean and work all the pots/switches/jacks. That will fix it 90% of the time.

    The other 10% is usually some type of dry joint on the PCB or (more rarely) a faulty component. You can often find those by flexing and tapping the PCB.
     
  8. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    yes i have tried swapping channels, ive checkes all transistor out of circuit, ive resoldered, and still nothing, channel a works perfect, but channel b is dead and sometimes when connected you can hear a cracking popping sound. this is a memphis pr400 two channel amp. ive cleaned everything down, the knobs on it i have also cleaned and still nothing
     
  9. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    disregard im new here and did that on accident. thanks
     
  10. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    the channel is sometimes dead and when it works you only hear a popping sound or crackling sound, what do you think the problem is, help would be really helpful
     
  11. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    hello there ive got a pr 400 memphis amplifier im trying to repair, one channel is good, but the other channel is dead and sometime when connected it pops and crackles, sounds nasty, ive cleaned and resoldered everything, ive checked all transistors out of circuit, caps look good, resistors ive switched out even though theres some that look brown put still reads resistance, i need help`. I just jhoined this forum yesterday, all help will be grately appreciated
     
  12. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Show me some good pictures.

    Cracking and popping ( if out put transistors are OK ) is caused mostly by a malfunctioning ( not shorted ) biasing or current mirror stage SS transistor.

    U need to replace them as it is very difficult to figure out, as out of circuit test will show good transistor.
    A method used here is to touch the casing of the small transistors one by one with the iron tip at around 200°C for a few seconds and hear if the crackling sound gets worse.
     
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  13. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    PS...One thread should be enough.
     
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  14. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I merged the three threads, the posts will show in order of the time.

    Bertus
     
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  15. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    well the bad channel when i connect it to a speaker is dead and then suddenly it pops and then goes dead again.
     
  16. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    the current transistors are irf z44...
     
  17. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    wen speaker is connected to bad channel, it sounds dead then suddenly pops and keeps on doing the same thing when it wants to.
     
  18. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    did you compare voltage measurements from the working side.

    Do you hear any thing when you input Audio from the bad side, low level or anything at all ?

    Show me a picture at least.
     
  19. misael.mata

    Thread Starter Member

    Aug 26, 2014
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    idk if ive explaines myself the right way but ok, when i hook a speaker to the bad channel, its dead and then all of a sudden pops and then goes dead again,
    but the other channel is working just fine. and what i also found out is that if i connect my speaker to both negative terminals i get sound......
     
  20. misael.mata

    Thread Starter Member

    Aug 26, 2014
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