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Zenith DVD Combo Home Stereo System

Discussion in 'Electronic Repair' started by [email protected], May 15, 2007.

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  1. Guest

    I have a Zenith DVD/Stereo Combo home theatre system. I bought it
    about 3 years ago. It worked very well until recently. It made a pop
    noise while operating and the unit powered off. Now if you try and
    power up the reciever, it will emit a high pitch frequency for about
    half second and completely shut down. If you try and power it up
    again, nothing happens but if you unplug the unit, wait 2-3 minutes
    and plug it back in, the unit will enter standby mode and the red
    indicator light will be on. Then if you hit the power button to turn
    the unit into active mode it will emit the high freq. noise again and
    shut off. Any advice you can give me on what the problem could be and
    how to fix it would be greatly appreciated.

    Thanks,
    Craig
     
  2. Arfa Daily

    Arfa Daily Guest

    Almost certainly caps in the power supply. Look for any with domed tops.
    They are very common as failures on the secondary side. If none look
    obviously bad, it will be necessary to check them with an ESR meter. Another
    possibility, if you heard a pop initially, is that one of the output ICs has
    failed, and is now loading up the power supply, causing it to go into
    shutdown. Often, the output IC's are on a separate board, with its own 3 or
    4 pin power connector coming straight from the power supply. You can usually
    just unplug this, which will isolate any output IC problems from the supply
    board. If you are not used to working with switch mode power supplies, be
    very careful as they are not isolated from the line voltage, and are thus
    potentially very dangerous. Also, the main primary side resevoir cap can
    stay charged to a very high voltage on a non-functioning supply, for several
    hours - or even days in some cases.

    Arfa
     
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