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Applevision 1710 monitor

Discussion in 'Electronic Repair' started by philippe brosson, Feb 17, 2004.

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  1. My Applevision 1710 monitor has intermittant problems. At power up,
    sometimes the monitor displays normally after a few seconds, sometimes
    it displays after 3 to 10 minutes and sometimes the screen remains
    completely black.
    I have read the recent news from Zeljko but i need more help.

    From my reading of the news, i suspect 3 sources of problem:
    1/the opto-isolator (Motorola MOC2A60-5)

    2/the PTC thermistor RP49 (i have read on the news that it is a PTC
    type, is it a PTC?)

    3/loss of the parameter settings in the processor of the CRT video board

    1/ opto-isolator Motorola MOC2A60-5
    Is it possible to short (pins 7-9) it definitively and switch off the
    monitor by switching off the main power on the monitor?
    In this case, the energy save feature uill not work. Do i will be able
    to use the monitor?
    The LED cathode and anode are respectively 2 and 3 (close). The load is
    between 7 and 9 (rather distant).


    2/ PTC thermistor RP49
    I measured on mine a value of 1100 khoms. On Anatek i found it should
    have a value of 4.8 to 5.4 khoms at romm temperature.
    Is it correct to replace the thermistor by a standard 4.7 khoms resistor?

    Where are the square blue J29P190 PTC thermistor and TL431 mentionned
    by Zeljko ?

    I have made a picture of the Applevision main board, showing the
    opto-isolator MOC2A60-5, the thermistor RP49 and IC TDA4605.
    (http://pbrosson.free.fr/applevision/mainBoard.jpeg)

    3/ reconfiguring the CRT video board parameters

    I'd like to reconfigure the CRT video board parameters with Apple's
    Display Service Utility (DSU) software
    Apple's DSU requires that a jumper (Apple part number 076-0529) be
    placed in a 4-pin connector labelled BV1.
    Apple docs indicate that only 2 pins need to be shortcut, but does not
    say which.
    I have numbered these 4 pins, please have a look at the picture of the
    CRT video board with its 4-pin BV1 connector at :
    http://pbrosson.free.fr/applevision/jumper.jpeg

    Looking in detail at the CRT video board, i found that
    pin 1 is not connected to any thing
    pin 2 is connected to pin14 of IV2 IC, to pin4 of IV4 IC and to pin39 of
    IV6 IC
    pin 3 is connected to pin12 of IV2 IC and to pin10 of IV6 IC
    pin 4 is connected to pin12 of IV6 IC

    I could try to short 2-3, 2-4 or 3-4, but i am afraid of damaging my
    monitor, so any information is *really* welcome.

    4/ Where i can find the model reference, pin designation and datasheets
    of these ICs of the CRT video board?

    IV2: 28 legs, with this label
    Motorola
    LSC 442 025CDWR2
    341 S0296
    6D56GLLGG9649

    IV4: 8 legs, with this label
    4LC21
    M /SN

    IV6: 44 legs with this label
    Motorola 3415
    0287
    V3.01
    LSC438802B
    341S0288


    Links
    Apple Display Service Utility(4.2.1):
    ftp://grijan.cjb.net:21000/macintosh/Manuals/displayservutil.sea.bin

    AppleVision service manual:
    http://preterhuman.net/texts/comput...plays-Monitors/applevision_1710av_display.pdf

    Datasheet on MOC2A60-5 opto-isolator:
    http://www.dialelec.com.

    Anatek:
    http://www.anatekcorp.com

    Thank you very much for your help.
    Philippe
     
  2. Zeljko

    Zeljko Guest

    Hello,

    Those threads are somehow mixed...didn't see Yours earlier.

    I didn't have intermittant problem - it was dead.
    If I remember OK, I saw no difference between shorted MOC and not shorted.
    Monitor was working OK. I could switch monitor ON only with signal (from PC,
    not MAC). And of course main power switch was ON.
    This is Your RP49. At this place I had blue PTC and it's not thermistor.
    It's Positive Temperature Coefficient resistor.
    TL431 is on Your pic north from RP49 - looks like transistor. Resistor 2K7
    is between RP49 and TL431. This resistor was blown on my monitor, and I put
    1K5 2W. Top side of this resistor is tied to the cathode of TL431. There You
    can measure 11V with respect to the primary ground (it's not chassis
    ground).
    If You suspect, buy new PTC and put it in. Check resistor 2K7 (if I see OK
    on Your pic). Replace small elko next to the TDA4605.
    You can use freeze spray (be careful) to find intermittant problems!

    Zeljko
     
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