kjchatman1
Member
It had a dead short to ground at c7804 which is pp3v3_g3h_pmu_vddmain. I injected 3 volts to find it. now pp1v8_slps2r is 0v. do i need to replace to capacitor or no?
-
For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.Subscribe Now
pp1v8_slps2r is missing on 820-01958
- Thread starter kjchatman1
- Start date
Board should start without it.
However, I recommend to solder another cap, once you get the board working.
However, I recommend to solder another cap, once you get the board working.
kjchatman1
Member
pp3v3_g3h is fluctuating quickly from 2.5v to 3.1v. could that be why pp1v8_slps2r isn't there?
kjchatman1
Member
replaced q7680 and it boots fine now
kjchatman1
Member
could the usb-c ribbon cause pp3v3_g3h to fluctuate? the rail shorted again and had the replace q7680. now pp3v3_g3h fluctuates sporadically from 2.0v to 3.1v. could this be a ribbon issue?
You can discard testing with known good one...
kjchatman1
Member
could the pmic cause the 3v3_g3h rail to fluctuate like that?
Still missing 1V8_SLPS2R?
PPBUS_G3H and 3V3_G3H_RTC are stable?
Inspect for corrosion between U7650 and Q7680.
Pay atention to R7691/97/98/99.
Also check R7685 and C7689.
PPBUS_G3H and 3V3_G3H_RTC are stable?
Inspect for corrosion between U7650 and Q7680.
Pay atention to R7691/97/98/99.
Also check R7685 and C7689.
kjchatman1
Member
the 3v3_g3h rail became stable but then after running the configurator i started getting 6.8 volts on 3v3_g3h afterwards . i get 3.3v without u7650 on the board and 20v on the amp meter. how is this possible without u7650 on the board?
Did you apply power without U7650, but Q7660/80 soldered on the board???
You are very lucky if none of them got burnt.
Do NOT do that again ever in your life!!!
Did you check all above mentioned?
Is the board still booting?
You are very lucky if none of them got burnt.
Do NOT do that again ever in your life!!!
Did you check all above mentioned?
Is the board still booting?
kjchatman1
Member
no it doesn't boot. u7800 was shorting the 3v3_g3h rail and was removed. Does the u7800 have to be there for 3v3_g3h to work?
Oops...
U7800 is the PMU chip (Power Management Unit).
It provides basic voltages to T2.
U7800 is the PMU chip (Power Management Unit).
It provides basic voltages to T2.
kjchatman1
Member
i'm getting no voltage for 3v3_g3h and it isn't shorted. does that mean that u7560 needs replacing?
Did you even check if U7650 gets correct power and enable signal?
kjchatman1
Member
i checked the circuit and it's just not producing 3v3_g3h. i don't want to put on a new PMIC until i get that rail working. do you know where i can get a new tps51980b?
Last edited:
Be sure to use TPS51980B there; NOT the A version.
On this board 3V3_G3H enable input is left floating.
All other boards where TPS51980A is specified, enable signal is driven high to enable it.
On this board 3V3_G3H enable input is left floating.
All other boards where TPS51980A is specified, enable signal is driven high to enable it.
kjchatman1
Member
ok thank you. I'll need to hunt down the correct chip