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#1 |
Senior Member
Join Date: Jan 2017
City & State: Atlanta, GA
My Country: USA
I'm a: Knowledge Seeker
Posts: 140
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![]() Board had previous liquid damage. It was initially ultrasonic cleaned. Keyboard, battery, and trackpad flex cable were all replaced and it worked fine. Board is back for no power. Hoping someone can help me out here. Voltages taken with board, DCIN board, and original 85W charger only, no battery.
PPPBUS_G3H - 12.54V PP3V42_G3H - 3.42V ALL_SYS_PWRGD - 0V (No pulse when triggering SMC_ONOFF_L ) PM_SLP_Sx_L - Pulses when triggering SMC_ONOFF_L PM_RSMRST_L - 3.28V PM_PWRBTN_L - 3.42V PCH_DSWVRMEN - 3.18V PM_DSW_PWRGD - 3.43V PPVCC_S0_CPU - 0V, No pulse PLT_RESET_L - 0V, No Pulse PP3V3_S0 - 1.69 - 1.75V fluctuating. PP3V3_SUS - 3.33V L7520 0v L7430 0V L7560 3.33V L7710 0v L3095 11.6v L7130 12.54 L7320 0V L7310 0V L7630 26mV U1950 PIN 5 - 0.8mV - 0.9mV seems to change (pulse?) between these two measurements. U1950 PIN 6- 0V, no pulse Board DOES start in SMC Bypass Mode with high fan spin. I'm really not sure what to do here. I'm still new to board level repair so I was hoping someone can look at this and help me figure out what is wrong. Thank you. |
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#2 |
Badcaps Veteran
Join Date: Feb 2020
City & State: Noosaville
My Country: Australia
Line Voltage: 240V 50hz
I'm a: Professional Tech
Posts: 329
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![]() With liquid damage, corrosion is often an ongoing process, especially if it's gotten under a BGA or two. Don't rush to ultrasonic clean a board; the original corrosion spots are your biggest clues in fixing the fault(s). Once you clean the board, all those pointers are washed away. If you have an iffy track/pad/via, they can be very difficult to find without those hints.
Take photos of the affected areas before rework so you know where to check if the job bounces. A good eye is very important when dealing with corrosion. Sometimes you can get crap under a BGA (like SMC etc) so this can cause all manner of issues. Having said that, PP3V3_S0 being low is where I'd start. |
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#3 | |
Senior Member
Join Date: Jan 2017
City & State: Atlanta, GA
My Country: USA
I'm a: Knowledge Seeker
Posts: 140
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![]() Quote:
![]() I went back and sort of studied the schematic. That lead me to U8030. I pulled it and a couple of it's pads looked kinda crappy, so I cleaned them and reballed U8030. Not only did it restore PP3V3_S0, but the computer boots now. Thanks again. |
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