1. Ttm3

    OP Ttm3 GBAtemp Regular
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    Switch won't start or charge. Charge meter shows 0 amps flowing. Voltages all seem to be correct with the exception of pin 6 on m92t36 shows no voltage. So far I've changed the charge port, fuse, m92t36, bq, p13usb. When I got this motherboard someone had messed with it and it was missing the cap on pin 5 of the m92t36. I replaced that with one from a donor. Also I have no shorts.

    I've never had a problem with them but I noticed max77621 being sold so I'm wondering if that could cause this.

    Thanks for and help & advice
     
  2. Ttm3

    OP Ttm3 GBAtemp Regular
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    i meant max77620 sorry about that
     
  3. bboerst

    bboerst Newbie
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    Pin 6 on m92t36 is the 5v input that I believe comes from p13usb.
    What does the voltage read on the large cap right above p13usb?
     
    Last edited by bboerst, May 19, 2020
  4. Ttm3

    OP Ttm3 GBAtemp Regular
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    I get no voltage on that cap
     
  5. Ttm3

    OP Ttm3 GBAtemp Regular
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    I've got another one now charging at ,05 amps. No shorts. Replaced all 3 chips. No change
     
  6. nero99

    nero99 GBAtemp Addict
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    might be a long shot, but the actual connector for the batter could be dead. did you test with a different battery to make sure it's not a battery fault after replacing those 3 chips?
     
  7. Ttm3

    OP Ttm3 GBAtemp Regular
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    Yes I tried a couple different batteries. ☹️☹️
     
  8. Ttm3

    OP Ttm3 GBAtemp Regular
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    Is pin 6 on the m92t36 input to the chip or is that voltage being provided by the chip? And if that circuit isn't shorted what could be causing it to be at 0 volts with battery attached and plugged in?
     
  9. SheriffBuck

    SheriffBuck Advanced Member
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    Pin 6 on the M92 is on the 3.3v rail which is powered from the MAX77620 on the other side of the board. It's an input to the M92.
     
  10. SheriffBuck

    SheriffBuck Advanced Member
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    I had one of these today. 0A charging. Turned out my VSYS rail was shorted with a knackered ceramic cap near the headphone amp IC. Whilst much of the switch runs from the 1.8v and 3.3v rails, there are a surprising number of subsystems which are driven directly off the VSYS rail which normally sits around 4v. You say you checked for shorts, but make sure you check VSYS too. There are obvious test points to the side of the BQ.

    Sheriff

    Sent from my SM-G975F using Tapatalk
     
    Last edited by SheriffBuck, Aug 3, 2020
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