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X-Post regarding "Hidden" Menu Settings

Discussion in 'Electronic Repair' started by ChrisCoaster, Jun 21, 2004.

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  1. ChrisCoaster

    ChrisCoaster Guest

    I need information that is impossible to find on line and would help
    me to deal with an issue on my TV. I'm serious - I've never seen it
    spelled out black & white! If somebody could please fill me in on
    the following:

    Bias: What it means

    What it does when it is adjusted

    Drive: What it means

    What it does when it is adjusted.

    I recently just figured out how to access the Service menu on my new
    Toshiba flat CRT, and I would like to correct a *slight* emphasis
    toward red. Otherwise, picture is just great and I don't think I've
    yet seen a TV picture so sharp and accurate out of box. So if just a
    minor adjustment in either Bias or Drive could correct the red
    emphasis beyond what the user "Tint"(R<--|-->G) could, please let me

    PS I take great notes – I've already written down the factory settings
    for Bias, Drive, Color center point and Tint center in the SMs.


    "When you forget you are watching movies on a TV - THAT'S a damn good
    TV! : )"
  2. Art

    Art Guest

    I certainly hope that you have the complete service menu for this TV before
    you change the service many parameters and forget what the original values
    were, or maybe you have the fore sight to actually write down the parameter
    locations and values before adjusting them.<
    Generally the bias is adjusted to produce a white raster without any
    evidence of overdriving the crt. Adjusted to below the point where blooming
    and retrace is being produced. Proper procedures will be laid out in the
    service menu as per cutoff settings etc. The individual drive settings are
    then set to minimize any shift in the colour of the raster when changing
    from a dark, barely visable raster, to a bright, fully illuminated one.
    Nomally called a tracking adjustment.
  3. ChrisCoaster

    ChrisCoaster Guest

    Okay! Soooooh. Which one, drive or bias, am I safe to adjust to take
    out some of the red??


  4. Jeff Wiseman

    Jeff Wiseman Guest

    I'm not familiar with your set exactly but before trying to do a
    direct change make sure that this is not a "marketing" adjustment
    that has it's own switch to be turned on or off.

    For example, Sony has an intentional red boost in it's color
    decoding. This makes the set's picture look really good in the
    showroom but exact balance cannot be achieved (i.e., when setting
    up the balance using color bars). In the service menu of some of
    their sets, there is a switch where this option can be turned off.

    - Jeff
  5. ChrisCoaster

    ChrisCoaster Guest

    Three days, five fastfold screens, 10 LCDprojectors and 400 feet of
    XLR, power, and VGA cable later, I finally read your reply Art. : )

    So I take it that Bias is (sorta) parallel to User Contrast/White
    Level, and Drive is parallel to User Brightness/Black level?

    -Chris"Dear Lord I hope I didn't get it backwards"Coaster
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