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Pioneer SX 850 Receiver

Discussion in 'Audio' started by [email protected], Sep 3, 2018.

  1. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    I recently purchased a used Pioneer SX850 receiver that was supposed to have a great sound, but when I turn the receiver off I get a really loud popping sound. This is with the volume turned to lowest point. I blew off the dust inside, but that didn't help. Anyone know what the problem is? Thanks for any help.
     
  2. nepow

    nepow

    99
    1
    Jul 18, 2011
    Other than the popping sound does the receiver work ok? and is the noise on both channels or only on one. Have you tried listening with headphones? Lastly is it just a single pop at switch off and do you get a similar noise at switch on.
     
  3. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    Thanks for your response. Only when I turn it off on both speakers. The stereo works fine. The phono worked well at first, but now the sound hardly comes through my speakers. I have not tried headphones.
     
  4. kellys_eye

    kellys_eye

    4,284
    1,145
    Jun 25, 2010
    Sounds as if one side of the output driver stage has failed. Can you get a service manual or schematic for it?
     
  5. shrtrnd

    shrtrnd

    3,666
    453
    Jan 15, 2010
    It's probably the receiver, but I'll mention this just in case:
    My Pioneer used to have the loud popping sound occasionally, and it turned-out to be the cross-over in the speakers. You'll probably end-up troubleshooting the receiver, but if I were you, I'd try the headphones if you can
    get a pair and verify the output of the receiver is the problem, and that you don't have a problem with the speakers.
    Do you have the polarity right on your speaker hook-up for each speaker? You might be getting a feedback pop from that. I try to check the simple stuff first before I tear into something.
     
  6. VenomBallistics

    VenomBallistics

    72
    26
    Aug 30, 2018
    well ... good news is you wont have to train a cockroach to solder in order to deal with any problems in that old beast.
    bad news ... You're going to need a crash course in discrete component amps just won't fit in a forum.
    Dont get all knee jerk under the hood of that baby. the power on her rails can purge the magic smoke out of just about anything if you're working with WAGs
    If you take the time to learn how a class B amp works, how its +/- sides cross over and tune at the bias generator, then work back. not only can you save it, you can build some slammin friends to go with it.
     
  7. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    Hello,
    Thanks for your response. It has taken awhile to answer back. I had to buy a new computer. I found out the popping sound and low quality sound is in the right speaker only ( I am facing the receiver). It doesn't happen, when I only have the left speaker hooked up. The speakers both work fine using another receiver. Does this still sound like an output driver?
     
  8. Ylli

    Ylli

    200
    37
    Jun 19, 2018
    That issue can be hard to troubleshoot. Let's start with the easiest. On the rear of the unit, lower center, there are a couple of jumpers that jumper the preamps to the power amps. Remove these (or at least the right one). Turn the unit power on and off - do you still get the popping?
     
  9. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    Thank you. Do these preamps just plug in, or do I need to remove the screws to remove them?
     
  10. Ylli

    Ylli

    200
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    Jun 19, 2018
    Capture.PNG

    Labelled L & R. These should be simple jumpers that can be unplugged.

    In addition, do you have a voltmeter available? If so, measure the *DC* voltage across the speaker out terminals with the unit on and the volume control set at minimum. Left and Right.
     
  11. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    I removed the right jumper. It still has a loud pop, only when I turn the receiver off. I will try the next step. Thanks.
     
  12. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    I don't know how to use the multimeter to test the voltage on the speaker out terminals. I put the probe in each red speaker slot, and it just blinked -0.00.
     
  13. shrtrnd

    shrtrnd

    3,666
    453
    Jan 15, 2010
    I don't know what Ylli is trying to tell you to check.
    My opinion of the symptoms you've described, is that you have a bad capacitor in that 'right side' speaker circuit.
    Do you have any troubleshooting skills in trying to track this problem down?
    What that means, I guess, is do you feel comfortable opening the chassis cover to check test points, or is that
    something you haven't done before?
    If you don't know how to troubleshoot, don't leave the receiver power plugged-in if you take the cover off, or
    you're liable to hurt yourself or do more damage than you already have.
    If you're not familiar with troubleshooting, I recommend you check with a repair shop to let them have a look at it.
     
  14. Ylli

    Ylli

    200
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    Jun 19, 2018
    [shrtrnd - I'm trying to determine if the amp is outputing a DC voltage that goes away at power off, or if it is outputting an impulse of voltage at power off].

    RDG, make sure speaker 'A' is selectred. Then use the voltmeter to measure the voltage across the speaker output where it says "Speakers/A/R nad Speakers/A/L".
     
  15. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    I talked to a repair shop tech, and he said it was probably the capacitor. He is 61 miles away with a 6 week backlog. Is the capacitor easy to replace? Thanks for your response.
     
  16. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    I made sure is was speaker A. I placed the red probe in the red slot and the black probe in the black slot. The R read -0.03 and the L read _18.34. But I don't know if I have the multimeter set correctly'
     
  17. Ylli

    Ylli

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    37
    Jun 19, 2018
    You indicated earlier that the problem was with the -right- speaker. Please trace the wires from the "L" output and see if they go to the left or right speaker.

    You really should not have 18.34 V across the speaker. This indicates a problem with the power amplifier. If *could* be a bad capacitor, but most likely it is a bit more serious. How deep do you want to get into this? No disrespect intended, but if you had trouble measuring the voltage across the speaker, I'm not sure I can walk you through any more involved troubleshooting. But I'll try if you'd like.
     
  18. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    If you could tell me the settings to use on the multimeter I might get a more accurate reading. Am I doing it right with the probes?
     
  19. Ylli

    Ylli

    200
    37
    Jun 19, 2018
    That's the correct way to do it. What range or setting for your voltmeter will depend on exactly what voltmeter you have. If it allows you to manually set the range, you would want to use the 20 volts DC (VDC) range. It might just have a range marked DC volts and will autorange. If that is the case, just look at the display carefully to determine if it says Volts (v) or Millivolts (mv).

    If you truly have 18 volts across one of the speakers, I'm surprised the speaker did not burn out.
     
  20. RDG@67

    [email protected]

    11
    0
    Sep 3, 2018
    I have a CEN-TECH multimeter. I went online to see how to use it. I followed the instructions, and I still get 18.36 on the L speaker. I tried it on the Speaker B system, and I got the same results for the L speaker. The R speaker was a little less. Maybe I should just let a tech look at it. I already have $400+ invested in this receiver off ebay, and I don't want to spend anymore on it. I think I got screwed. Thanks for trying to help me, but I am just a novice. I may try to sell it as is. Have a nice day.
     
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