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Onkyo AV Receiver repair

Discussion in 'Troubleshooting and Repair' started by mrmarcdee, Jun 25, 2015.

  1. mrmarcdee

    mrmarcdee

    21
    1
    Dec 16, 2014
    We have a Onkyo TX-NR509 AV receiver at work. Apprently somebody was charging their phone from the USB port with a frayed USB cable. They dropped the cable and it shorted out on something metal. I guess there we sparks. Anyways, when you press the power button the front display lights up and you hear two "up" clicks (power relays?) one after another, a 3 second pause, a 3rd "up" click, a half-second pause, and finally a louder, kind of multi-faceted, "down" click that seems to be the powering-back-off. So I took it apart.

    There is obvious burn around the USB port on the backside of the PCB. Seen best in photo #1-4 (4 is a closeup but with flash glare on the burn spot, 1,2,3 put the flash glare somewhere else) , the 4 solder points near the bottom between the two bigger ones are the 4 USB pins. Those 4 and all the stuff above that was burned. I tried to clean it up a little (before the pics) with some flux, but that also included scraping away burnt tiny pieces where you see L7504, L7503, L7502, L7501. Those kind of tiny components scare me. Those tiny ones are gone, what are they?. I don't care about the USB port, it can be removed or rendered useless or whatever, just want the receiver to work again.

    Photo #7 shows the whole front board, where the USB and front controls are. I removed all the screws but can't seem to get the board off. It seems to still be attached to something by where the volume knob is connected (that area is seen in photo #6). Any ideas how to get this off? Desolder the volume knob? Maybe the knob comes off just by pulling straight out which reveals a screw or something else?

    I found 3 fuses, they all look fine, not sure if there are any more.

    The connections in photo #10 look sort of funny/orange-ish to me, but I'm not sure.

    Would it be helpful to try and describe the general areas where I think the clicks are coming from? What should I check at this point? How would you go about diagnosing exactly whats wrong? Is there a schematic I should be looking up somewhere? If so where would be a good place to find it? Need any other pictures, or better pics? I have a multimeter and soldering iron and know how to use them (well...a little).

    Thanks
     

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  2. Martaine2005

    Martaine2005

    2,394
    630
    May 12, 2015
    Hi mrmarcdee,
    It does appear to be powering up, but the third click is going into 'protect mode'.
    Have you read the manual for trouble shooting?
    This may not apply to you but it does have a section for clearing 'protect mode'.

    Manual says..

    "The protection circuit has been activated. Remove
    the power cord from the wall outlet immediately.
    Disconnect all speaker cables and input sources, and
    leave the AV receiver with its power cord
    disconnected for 1 hour. After that, reconnect the
    power cord and set the volu
    me to maximum. If the
    AV receiver stays on, set the volume to minimum,
    disconnect the power co
    rd, and reconnect your
    speakers and input sources.
    If the AV receiver turns
    off when you set the volume to maximum,
    disconnect the power cord, and contact your Onkyo
    dealer".

    Might be worth a go. Nothing to lose.
    Martin
     
  3. Martaine2005

    Martaine2005

    2,394
    630
    May 12, 2015
    Sorry, I forgot the link.
    Page 59 is troubleshooting. Here

    Martin
     
  4. mrmarcdee

    mrmarcdee

    21
    1
    Dec 16, 2014
    That procedure did not work. Nope haven't read the manual, thanks for the link.
     
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