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Pioneer SX-850 Snap, Crackle and Pop

Discussion in 'Pioneer Audio' started by joe4fun, Jul 5, 2011.

  1. pjf610

    pjf610 Active Member

    Messages:
    207
    So My next question is do I need a heat sink??
     

     

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  2. QSilver

    QSilver Super Member

    Messages:
    1,201
    Is the transistor getting very hot?
     
  3. pjf610

    pjf610 Active Member

    Messages:
    207
    I have not changed it yet because I did not know whether I need a heat sink or not
     
  4. QSilver

    QSilver Super Member

    Messages:
    1,201
    If your replacing a smaller case size transistor to a larger case style then a heat sink may not be needed. If you are unsure, carefully run it and keep very close eye on temperature and make a judgement.
     
  5. pjf610

    pjf610 Active Member

    Messages:
    207
    Thanks QSilver will give that a go
     
  6. Juicer

    Juicer New Member

    Messages:
    18
    OK ... first off - thank you all for the replies - the popping and cracking was only present in PHONO - FM and AUX work well - I hardly ever use the FM and AUX only use this for playing records - last week a pop and crackle and lost my LEFT channel - from reading posts on here I replaced all the transistors on the AWF 011 bd - same situation - No Left Channel - looking at the schematic the -19V is -48V ??? Has anyone ever seen this?? I followed the signal that back to the Power Supply Bd.- please see the attached file ... any help would be greatly appreciated - please note I know just enough to get myself in trouble - :)
     

    Attached Files:

    • PS.JPG
      PS.JPG
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  7. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,910
    Location:
    Las Vegas Nevada
    Q6 shorted?
    The EQ issues probably took it out.
    You should replace the EQ transistors again.
    And recap it.

    C1 and 2. 80-MMK5104M50J01TR18
    C7 and C8, 647-UPW1A331MPD1TD
    C17, 647-UPW1V101MPD1TD
    C11 and C12, 647-UKL1H3R3MDDANA
     
    Last edited: Oct 5, 2018
    Juicer likes this.
  8. Juicer

    Juicer New Member

    Messages:
    18
    Thank you very much for the input ...I ordered the transistors for the PS board and should have them Monday or Tuesday. If that does not do the trick will reorder the transistors and caps - again, thanks for the help / suggestion ...have a great day !!!
     
  9. pjf610

    pjf610 Active Member

    Messages:
    207
    Hi all, what would be a suitable replacement for the 2SB536
     
  10. Juicer

    Juicer New Member

    Messages:
    18
    I would call Mouser ... their Tech Support is not only very knowledgeable, but very helpful.
     
  11. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    21,124
    Location:
    Bensenville,Illinois
    It would help if you detailed the model number (SX-850?), board number(AWH-059) and part number (Q11?Q12?) because there is never a simple answer.
    If the above assumptions are correct, you need 512-KSA940TU for q11,q12 and 512-KSC2073TU for Q9,Q10.

    Sometimes the factory part used and a replacement will not directly correspond.
     

     

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  12. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    21,124
    Location:
    Bensenville,Illinois
    When the phono amp tanks, if it's the power supply, it will kill BOTH channels, not one.

    Once new caps and transistors are installed, you should really do the FIRST thing and verify that the phono jacks
    in the back are actually connected to the phono inputs and the signal is making it through the switches AND
    in the case of PHONO 2 also the left and rightr channels are making it through the MIC jack!!

    Use the ohmmeter function of the DMM from the center contact of each of the 4 phono plugs, to pins 19 & 20 of the AWF-011 board. It should show 100 ohms on the switched-to input.

    Be aware that an unused (NOT switched to) phono input is connected to ground through each jack's 100 ohm resistor series resistor. Check the resistors as well, in case some schmuck blew them up.

    phono 1 left R2
    phono 1 right R1
    phono 2 left R3
    phono 2 right R4


    BTW Juicer and especially pjf610 - both should have started their own threads.... :bigok:
     
    Last edited: Oct 8, 2018
  13. Juicer

    Juicer New Member

    Messages:
    18
    Very sorry ... I was unaware - I made a comment a while back on this thread thanking everyone for their input when I first got my Pioneer - the info was very helpful - then - BANG - stuff hit the fan - please except my apologies
     
  14. pjf610

    pjf610 Active Member

    Messages:
    207
    Sorry
     
  15. Juicer

    Juicer New Member

    Messages:
    18
    I replaced Q6 and the -48V is now -19V and I have left channel in phono ... many thanks for the input !
     
    Last edited: Oct 10, 2018

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