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Sony STR-D650Z Stereo Receiver

Discussion in 'Electronic Repair' started by Michael Fiedler, Dec 11, 2005.

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  1. I am working on this receiver for my son. No sound, except for a
    little bleed through. I do get sound through the preamp and the phono
    amp, so I know that part is working; however, the tuner is not
    working. +12v line is 4.6v going to the tuner (and probably
    everywhere else). I get 4.6v at the output of the positive 12v
    regulator. The -12v regulator output is okay. It seems like there
    are a lot of places the 12v could be shorted in this receiver. Has
    anyone seen this problem, or if not, point me in the right direction?
    I am kind of stumped right now. Thanks in advance for any help.
  2. Guest

    If the 12V line were being loaded down that much the regulator should
    be so hot it will burn the skin off your fingers as soon as you touch

    If there is not excessive load then the regulator will not be so hot
    and there is a problem in the regulator circuit somewhere.
  3. Arfa Daily

    Arfa Daily Guest

    Agreed. On many occasions, I have had these 7812 monolithic regulators, go
    low output. 4 odd volts is about the level you do get out from them when
    they do this. If the regulator is not red hot ie being loaded into thermal
    shutdown by an external fault, just replace it.

  4. gb

    gb Guest

    IF you decide to replace the regulator, check the capacitors on the input
    and output pins (leakage, bulging, etc.) to the regulator -- good time to
    replace these -
    if problematic.

  5. Arfa Daily

    Arfa Daily Guest

    Thanks for adding that gb, I should have said. You tend not to think to say
    these things when you normally do it yourelf as a matter of course.

  6. Thanks for the info. The resistors on the input side of the regulator
    are a lot hotter than those on the input side of the negative
    regulator. All caps (input and output) near regulator look normal,
    although I need to take them out and check them on a checker. When I
    resolve this issue fully, I will repost my findings for others.
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