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53XBR45 Update.

Discussion in 'Electronic Repair' started by JURB6006, May 1, 2004.

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  1. JURB6006

    JURB6006 Guest

    Hey all;

    Jerry, thanx for your time, but troubleshoot how ? Only the Sony engineers know
    about their data structure. This is definitely a data problem, and the way
    adjusting the controls affected it I knew the PIN circuit was working.

    Sony tech line told me to change the EPROM in the tuner section, (IC7003 I
    think), which I did, and suprisingly the set STILL retained it's channel memory
    ! Just where is it stored ? What a trip. Regardless, the symptom didn't change
    after that, but it did change after IC3002, the EPROM near the jungle IC

    I looked at just about every data and clock line I could find and the only
    abberation I could find that coincided with the cyling behaviour was on the
    board with the jungle IC. IT was however NOT clipped high or low as I kinda
    expected, but data were cycling through the "active" time and it looked right.

    Now ANY chip that can write to the bus can cause this, and it seems there are
    plently of paths, so that eliminates it down to pretty local. There are not
    simply three lines for the whole set, obviously if it uses more than one EPROM,
    right ?

    I still have no exact print, but I'm fairly familiar with Sonys, any thing on
    THAT data line. Looking at it there doesn't seem to be much, just a micro, an
    EPROM and the jungle IC.

    I know it's not the EPROM, and because the menu sometimes mis-selects a
    function, I suspected the micro. However upon realizing that we had the jungle
    IC in stock, I decided to give it a try. FIXED.

    I put the old IC3002 back in and the geometry and everything was right on.
    Apparently the thing refreshes about every second and the jungle just couldn't
    hold the settings.

    The MAJOR thing this reveals to me is that the jungle IC might be able to write
    to the bus, but. . .

    1. It might not supposed to be able, it was defective
    2. Data are normally asyncronous even within their "frame" (I didn't recheck
    that waveform) and the CXA1477 has just a pinch of RAM to keep the DA
    convertors busy, because even a bad address decoder would screw up the
    settings, but it wouldn't cycle like that.

    Thing is it was normal for the short part of the cycle.

    The other important thing is that on the long part of the cycle it wasn't
    completely whacked, like no correction, it was as if it went back to defaults
    before the factory adjustment. It was aff about 10% Hsize, red and blue Hlins
    were off about the same. The raster was also slightly trapezoidal.

    It was as if the chassis had not been adjusted to the cabinet.

    This is why I didn't take Jerry's suggestion, the PIN cky was always working,
    just not fed right.

    The set is fixed, what I'm looking for here is your opinions about how I went
    about it. Having no print, I could have ordered it. However from a business
    standpoint this would be undesirable, this is an XBR45, it's older and there
    are not that many in our market.

    Opinions welcome, negative or positive, would you have headed straight for the
    jungle IC ? Print or no print. Did I get taken down the garden path only to
    find the solution in an unexpected place ?

    Thanks for your time.

  2. Jurb, I didn't follow this thread, so I don't recall the original symptom,
    but from what I can gather here and my experience with these, I would have
    really suspected the CXA1477. Most of the strange symptoms that I have seen
    in these sets have gone back to that IC.

    FWIW, I often don't read your posts very thoroughly because I find many of
    your sentences to be hard to follow. I'd be happy to provide help but when
    I see some thing like

    "Now ANY chip that can write to the bus can cause this, and it seems there
    are plently of paths, so that eliminates it down to pretty local. "

    which just does not make any sense to me (and appears to contradict itself)
    , I have to say, well, sorry, can't spend so much time on this...i.e. you
    might get more help if you cleaned up your posts and wrote more carefully.

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