Vconn input to M92T36 Explanation

Discussion in 'Switch - Console, Accessories & Hardware' started by bootaholic, Oct 17, 2019.

  1. bootaholic
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    bootaholic Advanced Member

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    I'll admit when i'm out of my comfort zone... this is one of those times. Working on a console that is unfortunately liquid damaged. Initially did not have any charge; cleaned corrosion and now get the usual 0.42A however, no boot. I've seen this a few times, usually not able to fix them (I presume due to faulty main chip).

    This one though has a shorted cap above the M92T36 chip. I've removed the M92T36 and the short goes away however even a new chip does not seem to resolve this issue which to me means something may still be corroded or damaged. Cap is ok. The shorted cap goes to the VCONN_IN pin (36 on M92). Can someone explain what this pin is responsible for and where this signal comes from? Is this signal passed off through some other logic gates within M92 and actual a result of another short on the board? Any help is greatly appreciated - see some photos below. IMG_20191016_184441 (1). Capture2.JPG Capture.JPG
     
  2. Agilato

    Agilato GBAtemp Regular

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    I would start with replacing those corroded caps near it, they can behave very unpredictable.
    Take off that metal plate and check what's there. If liquid get there you need ultrasonic bath.
    Some times liquid can short pins in usb-c port.
     
    Last edited by Agilato, Oct 17, 2019
  3. bootaholic
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    bootaholic Advanced Member

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    The schematic shows the input - VCONN has some sort of diode inline. Any idea where this would be?

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  4. Agilato

    Agilato GBAtemp Regular

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    I'll check later on my donor boards where this pin leads to.
     
    Last edited by Agilato, Oct 17, 2019
  5. Agilato

    Agilato GBAtemp Regular

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    Did you checked capacitor itself for a short? Here is what i found this pin share line with an element looks like resistor, right near. Here is a pic:
     

    Attached Files:

    Last edited by Agilato, Oct 18, 2019
  6. SolidSnakeUk89

    SolidSnakeUk89 Advanced Member

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    hmm it seems VCONN has something to do with the charging voltage I found the following references in similar chip applications:
    • VCONN Voltage - Measured on CC2 signal (pin B5) of the USB Type-C receptacle. Note - you may need to flip the USB PD analyzer over if VCONN ends up on the CC1 signal pin (A5).
    • VCONN Current - Measured across a 0.015 Ohm shunt resistor between the CC2 (pin B5) USB Type-C receptacle and the CC2 (pin B5) USB Type-C plug

    so it appears this is in the 5v power rail and it appears that it uses the CC1 & 2 (config pins) to detect whether the cable is connected on each orientation.To enable Type-C cables to be reversible, the Type-C receptacle is fully symmetrical. All power, ground, and signal pins are duplicated about the symmetry axis, which allows the Type-C plug to be flipped with respect to the Type-C receptacle. The Type-C plug offers only one CC pin, which is connected to one of the CC pins of the Type-C receptacle, to establish the Type-C orientation. The other CC pin is repurposed as VCONN (abbreviation for VCONNECTOR ) for powering the electronics in the USB Type-C plug.

    check this fella here... I think it is the Dc~DC buck converter for the main 5v Power rail so maybe is shorted?

    upload_2019-10-19_0-44-15.
     
    Borega, bootaholic and Agilato like this.
  7. bootaholic
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    bootaholic Advanced Member

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    Yep, checked cap itself by removing completely.

    Sent from my Pixel 2 using Tapatalk
     
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