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Help Guessing at Capacitor Values..

Discussion in 'Electronic Repair' started by Michael Kennedy, May 10, 2006.

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  1. I have a LCD controler that has some heat sensitive ceramic caps on it. The
    problem is they are SMD caps and have no markings at all. I bought the
    service manual for the sony sdm-hs73 monitor but it has no schematics..
    err...

    So with some educated guessing I was hoping we could figure this out.. The
    caps are directly connected to a Genesis GM2121 I.C. So I thought with the
    data sheet for the GM1212 that someone might be able to help me guess at
    what rating of capacitor I should use..

    All of the refrences to caps in the manual are from 2 to 9pf for inputs..
    and 16pf for outputs..

    Pictures of the board
    http://mikescomputers.homeip.net/LCD/DSC00388.JPG
    http://mikescomputers.homeip.net/LCD/DSC00390.JPG
    http://mikescomputers.homeip.net/LCD/DSC00392.JPG

    Genesis GM1212 Datasheet
    http://www.keil.com/dd/docs/datashts/genesis/gm2121_ds.pdf
    Quick way to get to cap values it search for pf

    Thanks in advace..

    - Mike
     
  2. Adrian C

    Adrian C Guest

    Nope, wrong search method :)

    The value you are looking at doing the above search is the internal
    'looking in' capacitance of the chip, for input and output ports!

    The parts you are interested in (surrounded by the yellow box) are
    connected to pins 130 to 136 are in the RGB input channels described on
    page 23 of the data sheet, the value given is 0.01uF (10nF). Having
    littered circuit boards with plenty of these SMD components in my time,
    and looking at your photographs at the size of things - my gut feeling
    is that 10nF is the value you should try.
     
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