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Followup (phone CLI add-on)

Discussion in 'Electronic Repair' started by Nigel Cook, Nov 17, 2003.

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  1. Nigel Cook

    Nigel Cook Guest

    update from 04 Nov posting
    I found some time to return to this project.
    Driving LCD from an af generator about 80Hz and
    about 3V pk-pk square wave. Too high a voltage and
    extra segments light, too high f and too feint and
    too low f then flickers. Also for determination the lines 29 to 36
    on the pcb show a different DVM "diode test" value ,
    back to the micro ,to
    ground, compared to the 1 to 28 lines (LCD disconnected).
    The LCD has 8 back-planes,
    (numbering on pcb) lines 29 to 36.
    33 to 36 relate to the (9 and 2 half) small digits and legends
    29 to 32 the 14 large digits
    For first 3 large digits and segments a to g (a at top ,then
    clockwise) and an extra
    double vertical segment (h) giving central segment of W.
    ( The double segment 5h is angled to give the right hand V
    segment of unaVailable and I of wIthheld as not alphanumeric dispaly )
    Control 'matrix' (for just lines 1 to 6 and 29 to 32 and digits 1 to 3)
    **/1 ,2, 3, 4, 5, 6,

    lines 7 to 28 for remaining digits 4 to 14

    For the UK anyway (digits 1and 2 blank) digit 3 only shows 0 for first digit
    of disclosed
    numbers so segment 3g off , 3g on only for the first - of "-WITHHELD-" and
    first 2 digits blank.
    the 1g segment is always off except for the first - of "-UNAVAILABLE-"
    As far as i can readup for multiplexed LCDs segments only 'light'
    when the timed stepwise voltages between BP and segment
    exceed some threshold
    folowed by the reverse phase of this voltage.Then relying on
    persistence to maintain till the next cycle if still driven.
    For all other smaller differences in drive voltages
    they stay unlit. To avoid doing timing circuits would it be possible
    to construct simple analogue differential amplifier
    monitoring lines 31 and 2 for
    'unavailable' and 31 and 6 for 'withheld'.?
    Just one phase sense ,say BP greater than segment by 2.2V or whatever
    (set on test),
    and ignore the the reverse phase which is only there to keep
    the liquid crystal happy, as far as i know.
    Integrated outputs each gating one of 2 tones or patterns on a sounder,
    heard between the rings of the phone.

    On second thoughts i will choose 4h (pcb lines 30 and 8 ) as
    the identifier of the vertical W segment
    of WITHHELD (AND the 5h 'I' of 'withheld' ) ,
    and 5h ( pcb lines 30 and 10) V of unaVailable
    as i seem to remember,very rarely, some displayed
    long mobile phone numbers use all 14 digits for the
    number of the phone so a 2,3,4,5,6,8 or 9 there would
    falsely register as withheld or unavailable

    e-mail (removing .....) .....k
    electronic hints and repair briefs , schematics/manuals list on

    Nigel,Diverse Devices,Southampton,England
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