3 USB-C Charging ports of 4 stay on 0V, 4th port functions OK
I’m a repair tech guy, and I’ve run into a really weird issue with a 15-inch Macbook Pro with 4 Thunderbolt ports: out of 4 Thunderbolt ports 1 port works totally OK (charges, boots, all 100% OK), the other 3 ports stay on 0V even if I plug in the charger. Not even 5V. 0V 0A.
The working port is the top-left port of the macbook (on the left of macbook, closer to the screen; If you take out the PCB and put it CPU up, it will be on the top-right)
No corrosion of any kind. Was reported as “not charging“, another store replaced the battery and it didn’t solve the problem, so it came to me. That’s all the info I have.
Tools I use:
1) BY3200 power adapter with MagSafe 1&2 and USB-C power delivery integrated. So normally when I plug it in, I see 0V before plug in, jumps immediately on plug in to 5V, 2 seconds later it becomes 20V and the macbook starts to boot. In this specific case, it’s just 0V, I plug the cable in and it stays at 0V as if I didn’t insert the cable at all (in any of 3 ports).
2) Openboardview and PDF schematic for Board 820-00281
Things I’ve tried/checked:
1) Ports themselves are totally OK. I can swap left and right port flexes around, doesn’t change anything. One specific port works, others 0V 0A.
2) Fuses are all OK (F3000, F3001…). Besides, they’re all completely independent circuits, 3 completely independent circuits on different sides of the board go dead all at the same time? Something fishy is going on here.
3) No shorts found.
4) I have researched the schematic. Out of every 2 Thunderbolt controllers CD3215C00, one is primary and one is secondary. The working port is connected to secondary controller.
I still don’t understand how 3 completely electrically independent ports give 0V 0A while 4th port gives full 20V and boot. All power lines from the ports meet at PPDCIN_G3H, which is obviously not shorted because I can charge and boot from the 4th port.
I believe the problem is somewhere between PPDCIN_G3H (where power lines from ports meet) and Power delivery charger, there is simply nowhere else for the problem to be with such behavior.
To power the CD3215C00, I need 5V from charger to become PP3V3_G3H. Which is again totally fine since it works with 4th port. But I don’t even get 5V on charger on the 3 ports, which is what freaks me out and what I totally fail to understand and have never seen before.
Why would power delivery stay on 0V? How could 3 totally independent ports die at the same time? What do they have in common that the 4th port doesn’t have? I’m kinda lost here. Spent hours with the thing, no matter what I measure, nothing of interest comes up. Despite years of repairing Macbooks, I can’t solve this one and I’ve never seen anything like it.
Update (10/23/2021)
Interesting development: on the working port charging begins only in one cable orientation. In another one it's the same 0V 0A as if I connected nothing
Update (10/23/2021)
Further addition: the 3 works that don't charge simply don't work at all, USB hub doesn't light up when connected to one of those.
좋은 질문 입니까?
댓글 2개
Next development: did diode mode on the ports. VBUS one 3 non-functional ports is 0.18V, on the working port it's 0.13V. No idea how to interpret this.
Ilya 의
Update: new flex cables arrived. Nothing changed in behavior: 3 ports 0V 0A and don't light up the USB hub, 4th port works 100% correctly with only one side, another side 0V 0A too (same as before)
Ilya 의