Pioneer SA-9100 Rebuilding boards

Discussion in 'Pioneer Audio' started by theoman, Apr 13, 2018.

  1. theoman

    theoman Confused Member Subscriber

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    Just finished rebuilding the AWH-023 Power amp boards, whats the safest way to test the boards before powering them up?

    IMG_9095.JPG
     
    Last edited: Apr 13, 2018

     

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  2. theoman

    theoman Confused Member Subscriber

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    here's the finished boards
    IMG_9106.JPG IMG_9107.JPG
     
  3. theoman

    theoman Confused Member Subscriber

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    anyone?
     
  4. theoman

    theoman Confused Member Subscriber

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    Ok so I just fired them up and one resistor on each board burned up. its the R20. When I was removing the parts the only think I found was Q11 or Q10 was shorted,
    IMG_9111.JPG IMG_9109.JPG
     
  5. petehall347

    petehall347 the brandy coffee man Subscriber

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    check pin outs on replacement transistors
     
  6. rcs16

    rcs16 Super Member

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    Thoroughly ohm out the o/p bjt pins vs the chassis ground.
    Thoroughly ohm out everything less :)
    Always power up on a DBT. Would think you have read enough threads to know this important point.
    Change the bias/offset pots.
    I suggest to only do one channel at a time, that way you can compare them to see if they measure the same on the ohmmeter first. Any node against the other on the other channel unless you are 100% confident in your work.
     
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  7. theoman

    theoman Confused Member Subscriber

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    I'll do this now, the resistor that failed is 120k but it says no wattage in the manual
     
  8. petehall347

    petehall347 the brandy coffee man Subscriber

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    schematic says 180 ohms . for r20
     
  9. petehall347

    petehall347 the brandy coffee man Subscriber

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    what is the board id number ?
     
  10. theoman

    theoman Confused Member Subscriber

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    when I ohm out the the chassis, what am I looking for?
     
  11. theoman

    theoman Confused Member Subscriber

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    IMG_9112.JPG
     

     

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  12. petehall347

    petehall347 the brandy coffee man Subscriber

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    schematic i have is for B version but i dont think for one minute they would have changed R20 to 120k .. it should be 180 ohms 1/4 watt . did it burn up in both channels ?
     
  13. theoman

    theoman Confused Member Subscriber

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    yes
     
  14. petehall347

    petehall347 the brandy coffee man Subscriber

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    what makes you think its 120k ?
     
  15. theoman

    theoman Confused Member Subscriber

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    I have the "E" pin of Q11 and Q10 at 15 and 18 pin
     
  16. theoman

    theoman Confused Member Subscriber

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    your correct its 180 I'm checking if I have all transistors in the correct direction
     

     

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  17. petehall347

    petehall347 the brandy coffee man Subscriber

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    did you manage to mix them up ? like install swapped one for the other ? are B and c to correct posts ? what about other transistors ?
     
  18. petehall347

    petehall347 the brandy coffee man Subscriber

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    q6 q7 may be in wrong . or maybe bias adjust pot was turned full up .
     
  19. AJD1964

    AJD1964 AK Subscriber Subscriber

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    Check transistor orientation.
    In one of the pics in post #4, it looks like the KSA992's? emitter legs are in a hole marked for the collector.
    Facing the front the new KSA992s orientation is ECB, left to right.
     
  20. theoman

    theoman Confused Member Subscriber

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