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Something zapped it

Discussion in 'Troubleshooting and Repair' started by TerryD, Nov 19, 2018.

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  1. TerryD

    TerryD

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    Nov 19, 2018
    I have a Sony STR D 1015 receiver that went kaput somehow while we were away...had it hooked up in my garage with a pair of basic speakers....worked fine..went away and came back to find the speakers blown , and only one side of the front amp works...
    so I am hoping there are some accessible fuses that blew...anyone know if and where they are located...
    Thanks,
    Terry
     
  2. Ylli

    Ylli

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    Jun 19, 2018
    I see 6 fuses in the power supply section, but nothing in the audio channels. the outputs do have protection circuitry that may be causing problems, but that would take some pretty deep troubleshooting.

    Do you get both channels if you use headphones?
     
  3. dave9

    dave9

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    Mar 5, 2017
    I doubt it's just fuse(s). With one side still working, I would suspect the output transistor(s) for the other channel are blown.

    It is curious that the speakers are blown unless someone was using it while you were away.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I'd it possible that the cause of the fault also cleaned the beer out of your fridge and filled your bin with empties?
     
    Dougnsalem and dave9 like this.
  5. TerryD

    TerryD

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    Nov 19, 2018
    yes, and thanks for your responses....all well with headphones...

    Yes, both channels work with headphones.....are those 6 fuses in the power supply section accessible? Could it be something as simple as blown fuses?
     
    Last edited by a moderator: Nov 22, 2018
  6. Ylli

    Ylli

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    Jun 19, 2018
    If it is working with headphones, that points to the speakers. You said one of the speakers was blown out, and then said only one side was working. How did you make that diagnosis? If you have one working speaker left, connect it to the left channel output - do you get sound? Now connect it to the right channel output - do you get sound?

    There is very little circuitry between the headphone jack and the speaker output connection in the receiver. There is a speaker switch and some wiring.....
     
  7. dave9

    dave9

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    Mar 5, 2017
    ^ While I don't have the schematic for this, it is possible there is a significant difference between the headphone jack and the speaker output.

    Some cheap/simple amps may just use a resistor divider for the headphone output, especially if the amp is based on a single IC, but in this case there may be one or more opamps and possibly a buffer too, then the headphone output is taken from there before getting to the speaker output transistors.
     
    Last edited: Nov 22, 2018
  8. Ylli

    Ylli

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    Jun 19, 2018
    Schematic snippet:
    Capture.PNG

    These are the main left and right channels, and I assumed one of these has the failure. Or is it in the 'surround sound' or 'back channel' output?
     
    Last edited: Nov 22, 2018
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    @TerryD, swapping the speakers over to see if the problem stays the same or swaps with the speakers is a simple first step.

    However it is possible that the amplifier has damages one of the speakers, and doing this will damage the other one. Ideally we would test the speakers first by connecting them to a known good source -- even a radio or an MP3 player might be fine.
     
  10. Ylli

    Ylli

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    Jun 19, 2018
    Good point *steve*. In addition, the TS might want to disconnect both speakers, turn the unit on, and use a voltmeter to confirm no (or minimal) DC voltage is present on the speaker outputs.
     
    (*steve*) likes this.
  11. TerryD

    TerryD

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    Nov 19, 2018
    thanks all for your feedback...I went out and checked today, and now all is good....I don't know what to say, except that maybe some circuitry requires a period of time where all power stays off for a while...nevertheless , I went side by side, L and R or Front and Back and got sound on all sides, and could not get it the other day...
    ....thanks once again for all your feedback, and Happy Holidays....now I can listen to Christmas music while working in garage.
    Terry
     
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