notsulla
New member
Hey everyone! First time posting and it’s going to be a long one but bear with me please!
I’ve been battling an A2251 ( 820-01949) that’s basically acting like a brick, and I’ve reached a point where I need some outside perspective. I’m trying to figure out if this board is a lost cause or if my next move makes sense.
The Story so far
I bought it second hand already non working posted for pieces or repair. When I first plugged it in, there was absolutely nothing no fan, no haptics, just a black screen.
I checked all the USB-C ports (with a multimeter i do t have those usbc readers) and they aren't behaving the same. Three of them get up to about 12.5V. But the back-left port (the Master DFU one) is stuck at a steady 1.55V. When I looked closer at that area, I noticed the flex cable of that specific port was cracked and broken, so ai bought a new one and replaced it. All good! But it didn’t solve it.
The 3-Second Loop
The board is stuck in this constant "heartbeat" loop. It stays at 11.2V for a second, climbs to 12.2V, then spikes to 12.76V for a tiny moment before it crashes back down to 11.2V and starts all over again. This happens on every single port. It feels like the T2 chip is trying to start the power sequence, sees something it hates, and trips the breaker.
The Short Circuit
I started poking around with my multimeter and found a massive problem on the SSD rail (PP0V9_SSD0). It’s showing a hard short to ground
The inductors L9030, L9020, and L9021 are all beeping to ground on both sides. I decided to take F7000 out and isolate some rails to see which part of the board was the fault in. In resistance mode found that C9006 was driven to the ground, so I removed it. Problem still stays, and I started suspecting U9000 (SSD PMIC) is the culprit. I did a resistance test between the 12V side (C9006) and the 0.9V side (L9021), and the numbers are incredibly low. It really looks like the 12V rail and the 0.9V rail have physically "welded" together inside that U9000 chip (I went a bit to hard on heat by mistake while readjusting a pad nearby).
The Current Problem
I'm ready to pull U9000 to see if the short on the 0.9V rail goes away, but I’m extremely unsure if it is even worth it as there are a ton of extremely small capacitors nearby which complicate the job a bit.
I'm wondering if that 12.76V spike is a known behavior when the T2 detects a shorted SSD rail. Does it make sense to pull the chip now, or am I just wasting my time since I can't do the DFU step immediately anyway? Also, if the 12V rail actually dumped into the 0.9V NAND, is it even possible to save this, or is the SSD likely fried?
Would love to hear any opinions (and critiques) and possible solutions to sabe this board, I normally don’t give up on boards easily. Thanks!
I’ve been battling an A2251 ( 820-01949) that’s basically acting like a brick, and I’ve reached a point where I need some outside perspective. I’m trying to figure out if this board is a lost cause or if my next move makes sense.
The Story so far
I bought it second hand already non working posted for pieces or repair. When I first plugged it in, there was absolutely nothing no fan, no haptics, just a black screen.
I checked all the USB-C ports (with a multimeter i do t have those usbc readers) and they aren't behaving the same. Three of them get up to about 12.5V. But the back-left port (the Master DFU one) is stuck at a steady 1.55V. When I looked closer at that area, I noticed the flex cable of that specific port was cracked and broken, so ai bought a new one and replaced it. All good! But it didn’t solve it.
The 3-Second Loop
The board is stuck in this constant "heartbeat" loop. It stays at 11.2V for a second, climbs to 12.2V, then spikes to 12.76V for a tiny moment before it crashes back down to 11.2V and starts all over again. This happens on every single port. It feels like the T2 chip is trying to start the power sequence, sees something it hates, and trips the breaker.
The Short Circuit
I started poking around with my multimeter and found a massive problem on the SSD rail (PP0V9_SSD0). It’s showing a hard short to ground
The inductors L9030, L9020, and L9021 are all beeping to ground on both sides. I decided to take F7000 out and isolate some rails to see which part of the board was the fault in. In resistance mode found that C9006 was driven to the ground, so I removed it. Problem still stays, and I started suspecting U9000 (SSD PMIC) is the culprit. I did a resistance test between the 12V side (C9006) and the 0.9V side (L9021), and the numbers are incredibly low. It really looks like the 12V rail and the 0.9V rail have physically "welded" together inside that U9000 chip (I went a bit to hard on heat by mistake while readjusting a pad nearby).
The Current Problem
I'm ready to pull U9000 to see if the short on the 0.9V rail goes away, but I’m extremely unsure if it is even worth it as there are a ton of extremely small capacitors nearby which complicate the job a bit.
I'm wondering if that 12.76V spike is a known behavior when the T2 detects a shorted SSD rail. Does it make sense to pull the chip now, or am I just wasting my time since I can't do the DFU step immediately anyway? Also, if the 12V rail actually dumped into the 0.9V NAND, is it even possible to save this, or is the SSD likely fried?
Would love to hear any opinions (and critiques) and possible solutions to sabe this board, I normally don’t give up on boards easily. Thanks!
