Hey there, i got a little question for you guys =)
i bought a broken A1990 with a shorted ppbus_g3h (5V, 0.045ma, 0.5ohms on ppbus_g3h).
I found that QA340 (gpu phase 3) was the issue and validated it by lifting LA340.
The short was gone.
I wanted to see, if the A1990 would draw 20V again, so i plugged the USB-C in and yes: 20V indeed.
I wanted to see how the Macbook would behave in this state, so i put the motherboard back inside the case and attached everything.
Plugged in the USB-C again and... i was back to 5V, 0.045ma. ppbus_g3h shorted again with now 10ohms.
For now i only checked ppbus_g3h to ground and ppbus_g3h to the inductors of the cpu / gpu. LA650 now has the the same reading(10 ohms), so it seems like QA650 has blown!?
I am not very experienced, but i was sure that i would not blow anything with attaching power to the machine in this state.
So i was hoping anyone could give me advice on this.
Was this expected behavior or just coincidence?
Thanks in advance :-*
i bought a broken A1990 with a shorted ppbus_g3h (5V, 0.045ma, 0.5ohms on ppbus_g3h).
I found that QA340 (gpu phase 3) was the issue and validated it by lifting LA340.
The short was gone.
I wanted to see, if the A1990 would draw 20V again, so i plugged the USB-C in and yes: 20V indeed.
I wanted to see how the Macbook would behave in this state, so i put the motherboard back inside the case and attached everything.
Plugged in the USB-C again and... i was back to 5V, 0.045ma. ppbus_g3h shorted again with now 10ohms.
For now i only checked ppbus_g3h to ground and ppbus_g3h to the inductors of the cpu / gpu. LA650 now has the the same reading(10 ohms), so it seems like QA650 has blown!?
I am not very experienced, but i was sure that i would not blow anything with attaching power to the machine in this state.
So i was hoping anyone could give me advice on this.
Was this expected behavior or just coincidence?
Thanks in advance :-*