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Pioneer SX-1250 Keeps blowing speakers right channel, Ideas Help?

Discussion in 'Pioneer Audio' started by electrocuted, Oct 9, 2018.

  1. Harvestor

    Harvestor Super Member

    IMG_20170723_182624993_HDR.jpg
    My D9'S
    And them next to my 380SE
    IMG_20170904_154950991_HDR.jpg
     

     

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  2. rcs16

    rcs16 Super Member

    Messages:
    3,891
    Location:
    Baldwin, Ontario, Canada
    Is there something wrong with your 1250? test the heck out of it on the bench with R loads, full power
    I think it more a case of methods, setup, expectations
    Some/many of these old speakers use low power drivers. I have blown my share of them. that is why I replace with something like a Morel, ones that are rated for much higher powers than OEM.
    I have yet to blow a Morel, still have the replacement tweeter diaphragm if I do blow one. They are not cheap but worth every penny
    I said to my friends I am sick of blowing drivers, I am going buy the next ones so that your ears blow this time :)
    If you are clipping your amp, you are in danger of blowing up higher freq drivers, hook a scope up to the o/p and you will be surprised how much your 1250 clips with vol set at 12 o'clock
    With multiple speakers, it is best to use more amps, that way they are driven at lower powers,less clipping, which actually results in lower speaker distortions and fatigue.
     
  3. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

    Messages:
    2,704
    Location:
    Calgary, Alberta
    Has the OP checked the DC offset??
     
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  4. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    I think I am still learning here. I only run one set of speakers at a time however. I
    I am going to try and check the DC offset once I figure out the actual process. It sounds simple enough but I just am not quite sure on how to do it. If one of you guys could explain it in dummy terms I'd appreciate it.
     
  5. spark1

    spark1 Super Member

    Messages:
    1,285
    Location:
    The Great Midwest
    Volume to zero, input to aux, nothing connected to aux, tone controls flat. Speaker selector to A. Connect one lead to A positive and one lead to A negative. Multimeter to DC voltage (mV setting). To avoid chances of shorting across the speaker terminals (NOT a good thing), connect meter with 1250 turned off. Once meter is connected, power up the 1250.
     
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  6. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    Excellent! thanks. I will try it tonight.
     
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  7. spark1

    spark1 Super Member

    Messages:
    1,285
    Location:
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    https://en.wikipedia.org/wiki/Parasitic_oscillation

    You really need an oscilloscope to determine if this is an issue with your amp, but even then it can be difficult to identify unless you are experienced. Some good pics of the power amp boards would be helpful, as incorrect outputs can result in oscillation, which in turn can damage speakers (and the amp).
     
  8. kevzep

    kevzep Its all about the Music

    If the amplifier has had a hard life, I would be checking all the emitter resistors. I notice these Pioneer SX poweramps love to take out emitters when run hard, or have had an output transistor failure.
    This would be a good start.
     
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  9. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    I loaded a couple pics of my DC offset readings. The channel in question is the highest one which seems double the amount. 20181010_210202.jpg 20181010_205026.jpg
     
  10. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    I loaded a couple pics of the MV offset at speaker outputs.
     
  11. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    One thing that has popped into my mind, I do remember now that on occasion I have heard a semi loud quick pop through the speakers which sounded like it may pr could have been a stray voltage spike. However nothing happened at that moment and things sounded normal. Obviously that is not something we want but I thought it worth mentioning.
     

     

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  12. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
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    What is the general opinion from you all on a meter like this for troubleshooting my 1250?
     

    Attached Files:

  13. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    I checked it tonight.
     
  14. kevzep

    kevzep Its all about the Music

    The entire amplifier needs recapping, suspect and known transistors replaced, certain resistors, relays replaced etc etc, if you don't, you'll be chasing your tail and pulling the amp out of service every other week to repair it.
    Get one of the BOM's off here, Mattsd has the best ones, hit it, order up and get the work done, and it will then give you years of trouble free service.
     
  15. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    https://www.ebay.com/itm/362267536415?ul_noapp=true

    I bought this kit to install. What do you think?
    https://www.ebay.com/itm/362267536415?ul_noapp=true

    I bought this kit to install. What do you think?
     
  16. redk9258

    redk9258 Super Member

    Messages:
    1,530
    Location:
    Illinois, close to St. Louis.
    I would have sourced parts from Mouser and / or DigiKey. People here have gone through the trouble of making BOMs and posting them. How do you know the quality of the parts or source from eBay? From a distributor, you get fresh, authorized, genuine parts.
     
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  17. electrocuted

    electrocuted New Member

    Messages:
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    Location:
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    I hear what you are saying but I didn't know at the time. I am going through the same issues trying to find quality parts trying to restore a vintage car right now also. I have learned more in the past few days just talking with you guys and am greatfull to have found this site.
     
  18. rcs16

    rcs16 Super Member

    Messages:
    3,891
    Location:
    Baldwin, Ontario, Canada
    I wish people would do more of this project BOM linking, it makes it so much easier for everyone.
    These BOMs need periodic maintenance as parts go in/out of stock & obsolete/discontinuances
    as i see there are a few parts on back order, i can suggest subs for them if you want to use this list.
    I guess the best is to have a thread for each assembly that way it can be managed and we can post info for each one.

    Pioneer SX-1250 Voltage Stabilizer (AWR-106)
    https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=0713019803
     
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  19. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

    Messages:
    2,704
    Location:
    Calgary, Alberta
    That doesn't look bad, good actually!!
    Good luck on the refurb!
     
  20. electrocuted

    electrocuted New Member

    Messages:
    37
    Location:
    South Florida
    Yes it does according to most peoples experiences. So now I'm thinking when it gets warmed up after a few hours of use something is giving way inside and causing damage to speakers.
     

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