Pioneer SX-1280 won't power on!!!

Discussion in 'Pioneer Audio' started by Spencer Bell, Sep 13, 2018.

  1. Spencer Bell

    Spencer Bell New Member

    Messages:
    14
    I recently bought a Pioneer SX-1280 from a thrift store, and I bring it home, flip the switch, and nothing happens. The switch doesn't seem to click when flipped, but rather moves smoothly as if it isn't catching anything. I really would prefer to fix this myself rather than ship it off to have it serviced. Hope you all can help!
     

     

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  2. Watthour

    Watthour Electron Rancher - JS3600

    If you feel the switch is a problem, you can unplug the unit, jumper between the switched and unswitched receptacles on the rear, then plug the unit back in. This will effectively eliminate the switch. If the switch is indeed the problem, replacements may be difficult to find, but not impossible.
     
  3. avionic

    avionic " Black Knights " Subscriber

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    The switch is probably OK. The SX-1280 has a soft-start circuit. There is a thermal fuse located under a large ballast resistor. If that fuse is history. Check your output transistors. One or more of them is probably shorted. The ballast resistor could be cooked as well.
     
    Last edited: Sep 13, 2018
  4. avionic

    avionic " Black Knights " Subscriber

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    Location:
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    [​IMG]

    Big ballast resistor is seen on the far left edge of the board, Below the black DEC relay. The thermal fuse is under it, You can see the lead of the fuse sticking out from under the resistor.
     
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  5. Watthour

    Watthour Electron Rancher - JS3600

    Fortunately, jumpering the the receptacles will not bypass the soft-start array.
     
  6. avionic

    avionic " Black Knights " Subscriber

    Messages:
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    Location:
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  7. avionic

    avionic " Black Knights " Subscriber

    Messages:
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  8. IMF_Pioneer

    IMF_Pioneer Active Member

    Messages:
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    Location:
    Australia
    I wish our thrift stores in Australia had such gems in them !
     
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  9. avionic

    avionic " Black Knights " Subscriber

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    Do you have the tools ? Can you follow a schematic ?
     
  10. Spencer Bell

    Spencer Bell New Member

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    Seems a little complicated, but something I would like to do myself! Probably could use a step by step guide.
     
  11. avionic

    avionic " Black Knights " Subscriber

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    Step one..Measure the resistance of the thermal fuse.In circuit will due.
     

     

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  12. KingBubba

    KingBubba "Too Much Stuff" Subscriber

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    I have a 1280 and love it. The output transistors are in an unusual mounting situation. The transistors are truly unobtanium, but there's a workaround here on AK somewhere. I think it was either echowars or markthefixer that pulled that together. avionic has probably done that too. He is a great helper. He was the first person on AK to give me assistance. You are lucky to have his assistance. Do a search and you may just find it if you need it later. Good luck on your challenge. Nice receiver.
     
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  13. avionic

    avionic " Black Knights " Subscriber

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    This is true.I have already located that thread by markthefixer.;) I suspect it will be needed.
     
  14. KingBubba

    KingBubba "Too Much Stuff" Subscriber

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    I knew that you would. You are just that kind of guy.
     
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  15. Spencer Bell

    Spencer Bell New Member

    Messages:
    14
    Ok so I found the problem! The power switch has been disconnected, but there is another problem. There is a white wire that runs from the switch to somewhere that I accidentally pulled out when I was trying to free the slack up on it so it would reach. I ended up pulling it out of somewhere, and I don't know where it came from. Thanks!
     

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  16. avionic

    avionic " Black Knights " Subscriber

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    How are your soldering techniques? The white wire will be easy to figure out. It goes back to Pin 2 on the little circuit board with 4 fuses (AWX-126 or -139 ) whichever board is installed in your unit.
     
    Last edited: Sep 18, 2018 at 7:58 PM

     

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  17. avionic

    avionic " Black Knights " Subscriber

    Messages:
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    The switch may be fixable..
     
  18. avionic

    avionic " Black Knights " Subscriber

    Messages:
    42,091
    Location:
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    You need to go buy a lotto ticket. Lucky man..
     
  19. Spencer Bell

    Spencer Bell New Member

    Messages:
    14
    My soldering techniques are very bad (probably because I have never done it before) HAHA
     
  20. Spencer Bell

    Spencer Bell New Member

    Messages:
    14
    The board on the underside of the receiver?
     

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