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SONY AE1C intermittant green-color HELP

Discussion in 'Electronic Repair' started by Adrian Glaubitz, Apr 30, 2006.

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  1. Hello,

    I have a 16-year old ;) SONY KV-X2531D (AE1C-Chassis) set which has been
    repaired several
    times already but still doing tough so far. Now it has started to drop
    green-color
    intermittantly meaning that it comes back after certain circumstances. I
    have made
    the following observations/measurements so far:

    Green drops in normal reception-mode giving the picture a red tint but
    picture visible, turning set
    into StandBy and turning it on again will sometimes bring the green back but
    mostly screen will just remain black (slight raster visible though). What
    really
    puzzles me is that activating videotext works (i.e. I get the text-picture)
    with green-color missing. But normal reception or OSD (green) does not show
    up
    (I'd expect the video also to appear with green missing, but video is just
    black
    and videotext with green missing). I cannot influence the color-dropping
    mechanically
    which would probably unveal dry solder joints.

    Anyway, I checked the voltages on the CRT-neck board:

    - 12V from video-board is okay
    - R,G,B from video-board measure around 12V AC
    - R,G,B directly on CRT-neck measure 280 (R), 350 (B), 480(G) AC-V

    So has anyone any suggestions ? I suppose this must originate somewhere on
    the video-board, since all video generated by the set itself works (except
    for green missing thus no OSD/videotext with no green) but external sources
    (tuner/AV) do not.


    Best Regards,

    Adrian
     
  2. Boba

    Boba Guest

    Try www.fixya.com they they are very good with TV's.

    Good Luck
     
  3. Art

    Art Guest

    Anything from cracked solder connections to corroded crt pins may cause this
    problem. Switch the drive signals from the main to the crt panel by swapping
    a few wires, (solder-unsolder, etc), red/green or blue/green and see if
    symptom follows the green drive or in possibly on the crt board or in the
    crt. Active or passive components from the jungle ic to the crt may be the
    cause. Good Luck.
     
  4. Hello,
    Hmm, but I checked the voltages of all colors and they seemed to be okay,
    didn't they (all read about 12V AC).
    Yes, thats where I already poked around but didn't find anything
    (at least cooling down with cooler-spray did not change anything).
    Databases say, that either jungle IC may be bad or one of the XTALs.
    I have now acquired the appropriate schematics for AE1C, I will
    check all the voltages and scope-diagrams on this board and compare
    with the references in the schematic. But what do I do when
    I find one voltage/diagrams to differ from the schematic ?
    Thanks,

    Adrian
     
  5. Hello,

    well, the set is pulling me a leg. Once I was about to start to check
    the voltages on the video-board, the picture turned back to normal
    while on without me even touching it *aaargh*. But I have resoldered
    many suspicous joints on the mainboard (D-board) including GND-connectors.
    The video-board had not any bad joints visible (it has small parts on
    it only). If the problem will come back, I will have to check
    the jungle-chip voltages and the clock-signal from both XTALs.

    Regards,

    Adrian
     
  6. Hi,
    Hooray !

    With the help of the Service Manual with schematics for AE1C, my
    DMM/Scope and freeze spray I finally found the one to blame ;).
    I traced the luma-signal up to the jungle-IC (TDA-4580/IC301)
    and up it to the latter it was okay. But the RGB-output of it
    was not ok. So I gave the jungle-IC a breathe of freeze spray
    with the set being on and a video signal connected and voila -
    the picture turned back to perfectly normal. After short
    period it would turn black again, so the jungle-IC is bad.
    I could reproduce this behavior any time and I also found
    some other posts with "NO PIC->REPLACE TDA4580", so I'll
    give it a try.

    I already bought replacement online and will have the IC (28DIL)
    be replaced by an professional technican at my work in university
    (I simply pulled out the B1 video-board), as he has a profesional
    rework station (as opposed to my soldering iron bought at Home
    Improvement ;)). I'm looking forward, whether this will fix it.
    I will post the results anyway.

    Regards,

    Adrian
     
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