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820-00281 - PPBUS 0.77v

2informaticos

2informaticos

Administrator
Staff member
USB meter shows 20mA because board runs on battery only.
Looks like HWMonitor follows the percentage correctly.
Strange to see wrong value reported by SMC, as HWMonitor reads the sensors through SMC.
Try changing SMC...
 
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tcampbell34

Member
I left it running a little longer and now macOS reports the battery at 84% but hwmonitor says 80%. It did stay at 100% for a long time though for some reason. I will check the SMC again later. Anything else besides U7000 that could cause this issue?
 
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tcampbell34

Member
Well I am still struggling with this one. I have replaced almost every component on page 64 on the schematic, including U7000 and Q7030/40 multiple times with the same results. I checked all the traces for each connection and they are fine. I even compared diode mode values on all the pads for U7000 with another board and they all match.

I get 19.8v on all pins of R7020 and on D1 for Q7030. I get 4.8v on TBA_BOOT1 and TBA_BOOT2 and on a good board I get about 17v on these rails. I also have only 4.4mv on TBA_LX1 and TBA_LX2, but diode mode to ground on these rails match my good board. LX1 and LX2 should be 12.6v according to my good board, which is what PPBUS should be, but I still have .7v on PPBUS. Does LX1 and LX2 come from U7000 or from Q7030/40, and what causes BOOT1 and BOOT2 to boost to 17v?
 
2informaticos

2informaticos

Administrator
Staff member
No idea, if you already changed all surrounding resistors and caps from the page 64.
R/C7030/40, as Q7030/40 and L7030 are the most important there.
Compare signals level with good board.
 
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tcampbell34

Member
I finally fixed this annoying board! It was a blown R3038 that was causing the issue. SMC_USBC_INT_L was 0v, which is how I found the blown resistor. Replaced that, and now the board boots from the charger and charges the battery.
 
2informaticos

2informaticos

Administrator
Staff member
Good to know, thanks.
All members should take notes and save valuable information on their service PCs.
Unfortunately, some people are reticent when I tell them to read all the forum threads.
 
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