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Sony RA-1 KP-46S25 "horizontal blinds" but NOT scrolling-help!

Discussion in 'Electronic Repair' started by 427Cobra, Apr 28, 2004.

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  1. 427Cobra

    427Cobra Guest

    Hi all. Hope someone out there can help me out a bit. First the
    Sound is perfect and colors are fair. The distortion does NOT "roll"
    and if you look hard there are visible scan lines in an arc at the
    bottom of the screen. All colors are equally affected. I checked the
    horizontal drive on the "A" board and base signal looks good (manual
    calls for 2.3Vpp) and 64Vpp out (manual calls for 144Vpp?). The
    service manual I have is for "V" series (KP-46V25)but has the same
    chassis layout (RA-1). The picture looks like this with or without
    video signal (AUX, ANT, RCA, etc.) so I'm ruling out this area. The
    manual I have is missing the "M" board waveforms so I'm not sure what
    to look for there. Any ideas? Thanks,
  2. David

    David Guest

    Troubleshoot the Vcc 15v and Vdd-15v supplies to the vertical output and
    convergence circuits first, then the vertical output ic, then the jungle ic.
    Then there is a possibliity eeprom data is corrupted going to the vertical
    section of the jungle ic.

  3. 427Cobra

    427Cobra Guest

    Thanks for your input. I just learned this thing uses a "switched
    mode" power supply that has electolytics that go bad. It could very
    well be one the +/-15VDC lines. I sure hope it is caps! I'll post an
    update. Thanks for the quick response!
  4. Is the ripple on the +/-15v supplies to IC501? Likely a bad cap on one of
    those supplies.

  5. 427Cobra

    427Cobra Guest

    Finally got back to work on this unit.
    I scoped all the DC voltages and they are clean and ripple-free. I
    started checking the parabolic and convergence (V) ckts and found some
    odd waveforms. Referring to the diagram here: (please,
    please excuse my "artistry") the waveform (FIG 1) is found at the
    V-Wave GEN IC1806 pin 6 (V-para) and convergence correction IC's
    1801,1805, and 1809 pins 6 and 12. The figure depicts incomplete
    arches in the waveform. The waveform in FIG 2 (should be a nice sine
    wave) is found at IC1806 pin 7 (V-sin). Vout on pin 30 of the Jungle
    IC301 looks like FIG 3 waveform. Defined sawtooth with barely visible
    ripple. I've swapped IC1806 with a known good one with the same
    results. I just ordered the DS ESR meter kit, so I can tackle these
    caps easier. Please forgive my ignorance. I'm self teaching myself
    all this (along with the help of wonderful folks like yourself!) and
    this has been the toughest one yet! What is a good source for parts,
    should I need to replace IC301 (CXA1477AS)? Thanks,
  6. Bill Jr

    Bill Jr Guest

    You should definitely replace that CXA1477AS

    Good Luck,
    Bill Jr
  7. 427Cobra

    427Cobra Guest

    Well, it sure was the Jungle ic. Put a new one in and it works great!
    Just need to focus it and will be good as new. Many thanks to all
    who put up with all my questions and guided me on my first rear
    projection TV set repair.
  8. remix

    remix Guest

    I just get a trouble with this TV , is just working an half of the screen
    (only on the bottom) the top is blank, the picture seems like encoded,
    only line of 2 is just display .

    Do you have any idea where the problem is ?
    Thank you to help me
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