Hardware 0 amps charging

[Ttm3]

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

 

[Ttm3]

i meant max77620 sorry about that

 

[bboerst]

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?

 

[Ttm3]

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?

I get no voltage on that cap

 

[Ttm3]

I've got another one now charging at ,05 amps. No shorts. Replaced all 3 chips. No change

 

[nero99]

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?

 

[Ttm3]

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?

Yes I tried a couple different batteries.

 

[Ttm3]

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?

 

[SheriffBuck]

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?

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.

 

[SheriffBuck]

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

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

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