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820-2530 ppbus .19 volts always stays green

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  • shanenin
    started a topic 820-2530 ppbus .19 volts always stays green

    820-2530 ppbus .19 volts always stays green

    I have an 820-2530 which is not turning on. I have 0.19 volts on ppbus with no short.

    The adapter light turns green and never changes to orange, does that indicate anything in particular?

    My only thought is isl6958, but I am not sure what enables I should be checking first
    Last edited by shanenin; 02-10-2019, 01:18 PM.

  • shanenin
    replied
    It is official, it is dead: 23k ohm.

    Leave a comment:


  • 2informaticos
    replied
    Its age is a good reason to get bad...

    Leave a comment:


  • shanenin
    replied
    Thanks 2informaticos for your patience and help :-)

    on a side note,any idea what would damage the MCP?

    (I have not yet verified thst is the problem, but that uneven frequency seems bad)
    Last edited by shanenin; 02-28-2019, 09:55 PM.

    Leave a comment:


  • 2informaticos
    replied
    Yes, lower value denotes bad MCP...

    Leave a comment:


  • shanenin
    replied
    I will test this later. Why are we checking for less than 30k on pp3v42 ? What does that indicate? I am guessing bad mcp, if so why?

    Leave a comment:


  • JohnB8812
    replied
    Yeah agreed less than 30Kohms this junk

    Leave a comment:


  • 2informaticos
    replied
    Post resistance to ground (ohm scale) at 3V42 power rail.
    You must get more than 30K...

    Leave a comment:


  • shanenin
    replied
    we do have 1.05v at c7771. I was looking for a clock chip and realized that is part of the MCPs job. I did check for a frequency at rtc_clk32k_xtalin and out and I get an erratic reading between 31 and 36mhz (jumping)

    I am not getting any pulse on pm_slp_l when touching smc_onoff_l to ground

    Leave a comment:


  • 2informaticos
    replied
    Solder a wire on SMC_ONOFF_L line and touch the ground (momentary).

    "Do you get 1.05V at C7771?
    If not, change that cap..."
    Can we get a reply?

    Leave a comment:


  • shanenin
    replied
    Thanks for taking the time to explain these things. I did know they were signals, but I see my mistake. The name was referring to the power rail it started, not the voltage of the signal.

    I attached a wire to pin5 of the keyboard connector and tapped the other side to ground to mimic pressing the button, but I am not getting any pulse on pm_slp_s4. Was that a correct way of starting the system?

    Could I also short smc_onoff_l to start it?

    Leave a comment:


  • 2informaticos
    replied
    MCP platforms never start when charger is plugged in; another wrong assumption.
    Only iCore boards start this way.

    "why would I not assume based on the names"
    Just for that; pay atention to ENTIRE name.
    EN and PGOOD mean something; they are signals, not power rails...

    Leave a comment:


  • shanenin
    replied
    Originally posted by 2informaticos View Post

    PM_SLP_S4_L should go high when press power button.
    when I start it by attaching the magsafe it is not pulsing.

    I think I have checked all of my s5 rails, but this older board seems different than I am used to and it does not seem to have many listed in the schematic
    Last edited by shanenin; 02-28-2019, 12:09 PM.

    Leave a comment:


  • shanenin
    replied
    why would I not assume based on the names P1V05_S5_EN would be 1.05 volts and P1V05_S5_PGOOD is also 1.05 volts? I am asking to try and learn and understand

    Leave a comment:


  • 2informaticos
    replied
    Wrong assumptions.
    Do you get 1.05V at C7771?
    If not, change that cap...

    PM_SLP_S4_L should go high when press power button.

    Leave a comment:

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