Sharp VCR VC-M331SM(SS) repair, doesn’t turn on (in cold state)

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  • Chungalin
    Badcaps Veteran
    • Jul 2014
    • 422
    • Spain
    #1

    Sharp VCR VC-M331SM(SS) repair, doesn’t turn on (in cold state)

    This old Sharp VHS VCR didn’t start after being unplugged for some months. It turned on after warming up naturally (long time) or shortly after forced warming with hot air on primary side of Switching Power Supply.

    Primary controller is IC902, a Panasonic AN8027, and switching mosfet is a SanKen 2SK2848. When SPS starts working you can clearly hear a subtle and characteristic *click* coming from the IC (or the mosfet? I’m not sure) and fluorescend display shows "SHARP".

    Just replace primary small caps C913 (22uF/50V) ) and C914 (10uF/50V), both related to feeding IC902. Now it powers on at once, even in cold state. BTW, both show a normal ESR of 1,1Ω and only capacitance is slightly degraded.

    Everything else is fine (tape mechanism, belt, roller, video output, secondary caps...).
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