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Sharp TV lost vertical, Questions about vertical output chip?

Discussion in 'Electronic Repair' started by Mike, Sep 24, 2006.

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  1. Mike

    Mike Guest

    Sharp model 25A-S100
    Vertical output chip NTE7039

    In the past TV had intermitant vertical problems, resoldered pins 13,
    12 and 11 on NTE7039, good for two years. Now have just horizontal
    line acroos screen. No schematic.

    Questions
    Pin 8 pump-up output, does the chip supply that Voltage or another
    circuit?
    Pin 2 is this 4.45V over driving the trigger, cause of failure?
    Pin 13 Where does this Voltage come from?
    I can order a NTE7039 for $10.00.
    Just not sure if it's the NTE7039

    Thanks for any info

    pinout My readings data specs

    1 +VCC1 10.29 V 8-14 V
    2 Vertical trigger input 4.45 V
    Max 3.2 V
    3 time constant 5 V
    4 Vertical amp control 5.2 V 5.9-6.3 V
    5 Vertical size control -.004
    6 Ramp generator 4.96 V
    4.6-5.2 V
    7 Vert out AC/DC feedback -.006
    8 +Vcc8 -.282 V 10-27 V
    9 pump-up output -.208 V
    10 OSC stop -.001 V
    11 Grnd
    12 vertical output -.004 V
    13 Power supply for vertical output -.004 V Max 62 V


    Features:

    Low Power Dissipation due to On–Chip Pump–Up Circuit

    On–Chip 50/60Hz Vertical Size Control Circuit

    On–Chip Sawtooth Wave Generating Circuit

    On–Chip Drive Circuit

    Vertical Output Circuit

    On–Chip Thermal Protection Circuit

    Excellent Interlace Response

    Excellent Crossover Response

    Recommended Operating Conditions: (T A = +25....C unless otherwise
    specified)
    Parameter Symbol Min Typ Max Unit
    Driver Supply Voltage +V CC 1 8 12 14 V
    Pump–Up Supply Voltage +V CC 8 10 24 27 V

    Absolute Maximum Ratings: (T A = +25....C unless otherwise specified)
    Driver Supply Voltage, +V CC 1 max 15V . . . . . . . . . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    Pump–Up Supply Voltage, +V CC 8 max 30V . . . . . . . . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    Output Supply Voltage, +V CC 13 max 62V . . . . . . . . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    Deflection Output Current, I DEF –1.5 to +1.5A P–O . . . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    Thermal Resistance, Junction–to–Case, R thJ–C 4....C/W . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    Allowable Power Dissipation (With Infinite Heat Sink), P D max 8W . .
    .. . . . . . . . . . . . . . . . . . . . . . . . .
    Operating Temperature Range, T opr –20.... to +85....C . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
    Storage Temperature Range, T stg –40.... to +150....C . . . . . . . .
    .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
     
  2. Franc Zabkar

    Franc Zabkar Guest

    This is a replacement for the LA7838.

    See http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm
    Vcc8 is an externally supplied power rail. Look for a feed from a
    secondary winding on the flyback transformer. You'll probably find an
    open, low value, fusible resistor.

    A datasheet, including application circuit, for the LA7837 and LA7838
    is available here:
    http://www.audiolabga.com/pdf/LA7837.pdf

    - Franc Zabkar
     
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