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Info needed on 2 tough repairs; 1 solved!!!(part 2)

Discussion in 'Electronic Repair' started by Vector Viper, Jan 27, 2004.

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  1. Vector Viper

    Vector Viper Guest

    2) Sony 32" KV32XBR37 Chassis SCCF84VA
    Came in dead, had the classic blown power regs (C4834)+blown output
    Replaced all+the black vdr, found bad connection on 'E' of hor-out,
    thought it fixed
    after soldering everything....
    Horout will now run MAYBE 1 min before blowing; gets hot pretty
    fast....can't see pix
    before this happens. Did sub a D1880 for hor out to get this
    C4927 blows in SECONDS. For each horiz pulse at HOT, the trailing edge
    is lifted off the
    baseline (not sharp) tried swapping flybacks with a known good one with
    no change.
    disabling pincushion by pulling link coil WILL allow set to run with
    bowed picture,
    but HOT still gets too warm....What could the problem possily be?! bad
    The yoke is a 8-451-315-41. The hor winding measures 713uh on mine, if
    someone has a listing
    on specs for this part, let me know? I'm really stumped on this one...

    I feel so stupid....when it came in, it had a huge burn/arc mark on the
    Emitter of the
    Hor out transistor; this was a clue. It turns out the horizontal drive
    transformer was BAD,
    probably a fried secondary. The hor out shorted C to B, sending +135V
    through the
    transformer back to the emitter coil...
    The bad xformer measured 238mh primary, 5.4 uh secondary. (with 1 or 0
    A good one was 1 think 150 mh on the secondary...
    This also proves a D1880 will run with lower drive, a bit higher gain, I'd

    Here's a big hurrah for keeping spare part boards!!! HURRAH!!

    Aaron H.
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