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LG Model C17LC-0 with strange shutdown

sawwa7 29 Mar 2010 17:34 4035 7
  • #1 29 Mar 2010 17:34
    sawwa7
    Poziom 12  

    Hi all colleagues
    i have this LG Model : C17LC-0 based on Chassis CA-136 which has a strange problem !
    the monitor power on with a solid green led and getting the no signal coloured pattern on the screen and as soon as the data cable is connected to the VGA card on the pc , the power led flashes green(blinks) and the no signal disappear with a totally black screen .
    the cable measured ok , specially HS and VS untill reaching the Micom IC401 pins 52 and 53 respectively !
    measuring voltages from power supply and got all voltages ok
    80V , 50V , 13V ,6.3V and 5V are all ok
    also 40V , 400V ,G1=-160V and G2 are all ok
    while the data cable ( D-Sub 15 pin cable) is disconnected from VGA card ,but once the cable is connected to VGA all voltages go slightly high with about 1V and the power led starting to blinks and the no signal pattern disappear , this also happen if i used any VGA card even if it wasn't connected to a pc !!

    has any one comes accross this fault before?
    any idea what could be the problem and why it's occure even if it's connected to any VGA that's not connected to any PC ?!
    there's no HS or VS when the VGA is ouside the PC and supposed to get the same no signal message , but just got the monitor shut down with blinks from the power led and no horizontal outputs !!
    please help if u have seen this fault before and many thanks for any help given .
    Kind Regards

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  • #2 30 Mar 2010 17:42
    sawwa7
    Poziom 12  

    Hi again
    please help guys :cry:
    the monitor works perfectly while the D-Sub 15 pin cable is disconnected from VGA card and the power led lights solid green with all voltages ok and the no signal message on the screen, but when the D-Sub cable connected to any VGA card the horizontal stage shuts down even if the VGA card is outside the computer case :!:
    what's make the monitor shuts down the horizontal stage while no signal is coming out of the VGA card?
    is it a cpu problem?
    thanks for any help given
    Kind Regards

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  • Pomocny post
    #3 31 Mar 2010 18:46
    lisek
    Spec od monitorów

    Check C417 and elements pin,.40 /39 IC401
    Check Q719 Q706 signals SDA SCL
    pin.30 SAA4849PS (value voltage 2,5-3.1V)
    * uPc sometimes had name LGM41B-030C-007

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  • #4 01 Kwi 2010 19:42
    sawwa7
    Poziom 12  

    lisek napisał:
    Check C417 and elements pin,.40 /39 IC401
    Check Q719 Q706 signals SDA SCL
    pin.30 SAA4849PS (value voltage 2,5-3.1V)
    * uPc sometimes had name LGM41B-030C-007


    Hi lisek
    Thanks alot for your answer , i've tried an empty dump but unfortunately got the same symptom with a white screen with 15 pin D-Sub Cable disconnected , i've tried another dump from the web but nothing changes and all the 5V zener diodes in the signal lines of the D-sub Cable has been checked before posting and all were perfect .
    i've also checked all components around pin 39 and pin 40 of IC401 and they are all having no problem , C417 and pin 30 changes voltage from 2.9v in working mode to 3.2V in shutdown mode , signals to B-Drive Q719 and HOT Q706 are working fine when the D-Sub Cable is disconnected and both of them cut off as soon as the D-Sub cable connected to any VGA whatever it's connected to a pc motherboard or even u are catching this VGA in ur hands :evil:
    i've tried to test protection circuits and disconnecting pin 1 of IC401 makes no difference , also disconnecting the X-Ray pin 22 also makes no difference :roll:
    one more thing is the 40V that comes from the FTB pin 5 to C739 was slightly high and reads 45V , but disconnecting the x-ray pin 22 of IC401 makes no difference .
    does this means a faulty IC401 (2x1 micon and synch processor) ?
    any more help or suggestion ?
    thanks for any help given

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  • #5 02 Kwi 2010 17:29
    sawwa7
    Poziom 12  

    Hi again

    what's new is when i disconnect pin 6 ST-IN of P402 which is connected to pin 56 of IC401 the monitor didn't shutdown and still give me the no signal pattern but no video is coming from the VGA card to the screen and no key works from the monitor front control panel menu and selection keys (not functions) , it's the same as disconnecting pin 56 of IC401 from the main board , which means that problem is inside IC401 !!
    is that insures a faulty micon ?
    what does this ST-IN pin 56 stands for in this LGM41B-030C-007 (SAA4849PS) micon IC401?
    any further comments or help?

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  • #7 02 Kwi 2010 21:00
    sawwa7
    Poziom 12  

    lisek napisał:


    Hi lisek
    thanks a lot for your help and support :)
    unfortunately , this is what i've got when following this link :

    LG Model C17LC-0 with strange shutdown

    i do have the schematic of this monitor but wanna get sure if the micro IC401 is gone or i'm still having some hope for repair ?
    what do u think?
    thanks for any help or hint?
    i've checked everything u told me about but nothing was wrong and also tried more than one eeprom dump , it's actually the same as 710E model .
    thanks again and long to hear from you as quick as possible as :)
    good luck

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  • #8 05 Kwi 2010 10:40
    sawwa7
    Poziom 12  

    sawwa7 napisał:
    Hi again

    what's new is when i disconnect pin 6 ST-IN of P402 which is connected to pin 56 of IC401 the monitor didn't shutdown and still give me the no signal pattern but no video is coming from the VGA card to the screen and no key works from the monitor front control panel menu and selection keys (not functions) , it's the saem as disconnecting pin 56 of IC401 from the main board , which means that problem is inside IC401 !!
    is that insures a faulty micon ?
    what does this ST-IN pin 56 stands for in this LGM41B-030C-007 (SAA4849PS) micon IC401?
    any further comments or help?


    The monitor come back and worked fine now with pin 6 of P402 disconnected or pin 56 of IC401 disconnected :D
    thanks all colleagues

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