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Onkyo TX-8050 Stereo Receiver, Bad Transformer

Discussion in 'Troubleshooting and Repair' started by KilgoreCemetery, Sep 19, 2020.

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  1. KilgoreCemetery


    Apr 12, 2017
    So, I have an Onkyo receiver that will no longer power on. No standby light or anything. Long story short, I've discovered that the primary side of the standby transformer is open. It shows NPT-1520JQ on a sticker on the side, but I can't find much info about it. Luckily, I was able to find a schematic!
    Onkyo TX-8050 Power Schematic.jpg
    I would like to just buy a new replacement for it, but I'm unaccustomed to replacing such things. I'm guessing that the secondary side needs to output about 10-12VAC, but is there any way for me to calculate what amperage it should be rated for?
  2. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir KilgoreCemetery . . . . .

    Examine the two primary windings ends terminating and being soldered to their two thermoplastic lead wires and determine if there might be a hidden thermal fuse in series with that winding, and being hidden under the tape/paper/fishpaper wrappings.
    This minor T-former is just for the units standby linear standby supply and runs 48 hours a day . . .the BIG main T901 transfomrer hints of an internal thermal fuse at its primary.

    Looking at the secondary of the transformer looks like it feeds 3 different power sources FWB rectifiers arrangements.
    Outputting at a 12V AC'ish and declining secondary levels seeming to be in order.
    If another has to be located. It would be less than an amp in current rating.
    And with its primary being across the AC power line CONTINUALLY, its typically being a " high impedance winding ", wherein they will have used more inductive turns for a cooler running unit.

    First see if a thermal fuse is open . . .vice the t-formers actual primary winding .

    73's de Edd . . . . .

    I am an insomniac . . . . . . but I don't worry about, and lose any sleep over it !

    KilgoreCemetery likes this.
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