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12v rail is present, PMU is operational and sends out PMU_SYS_ALIVE to UN400 UN400 does not send out P2v5 NAND0 EN I did not find any shorts. All the CPU rails are up. PMU is working NAND rails have no shorts. The power is just not being turned on. Did not observe data on 12c_SCL or SDA...

I run across some of the 15" units that are having GPU problems. Like one every two weeks. Was considering starting to change these. Is anyone else seeing this too?

RP884 & RP845 shows up as 0 ohms on the schematic but is actually 10 ohms. I double checked this against a known good LB. Driver is not pulling down 12v enable signal and turning on the buck. Not sure why I have replaced it. This was a liquid damaged board so who knows here. I will update...

Thought I would share some good information. I had a A1466 come across my bench with nothing I have ever seen before. You would power it up and the unit would pull normal current, chime and boot but the screen would flash a sold red screen for a few seconds switch to Blue, green and then...

I got a water damaged 820-01987 came in with no back light. water damage around U8400, fixed trace damage and replaced U8400 Then found a blown fuse F8400. After this the backlight voltage came back but it would quickly fade away and only went to 12v not 50. The CPU would quickly...

I am starting to see more and more of this so I believe it is not a isolated incident. Flawless, clean units. No water damage of any kind. Look like they just left the factory. Unit not switching to 20v Thermal shows short on U7700 by quick looping Short located on C780B and C78201. Power...

The board powers on. The PP3V3_S0SW_LCD will flash 3.3v only for a moment 1/2 sec and then it goes away. I have traced this back to the EDP_PANEL_PWR_EN signal which also only flashes on for a split second. Comparing against my test board this should stay on even with a panel not connected...

The unit would not switch from 5v on the power supply. PP3V42 was missing. The ISL9239 was bad After replacing it I got my PP3V42 rail and the CD3215's enabled 20v PP3V3_S5 is missing. P3V3_TBT_T_SX_EN_R is missing and the PP3V3_S5 rail never happens. I have tried both sides all of the...

S0 state. All rails are present. no sign of water damage. CPU never sends BL enable. Image never appears. CPU warms up and current draw and thermal imaging are consistent with a working machine. No data traffic "DP_INT_ML_C_N"

This is a odd one. Don't know where to start. Came in to me with intermittent crashing on battery. "which I really can't duplicate" The battery was just replaced before I got it. Customer said it does not crash when on the AC adapter. Have you seen this on this board? Are we looking at...

The coils for the GPU buck converter are glowing on thermal. I usually don't notice buck converter coils glowing like this but I have little experience with this board and I don't have anything I can reference against. Unit came in for "throttling fans at full speed" Unit was pretty dusty...

Was given to me as "no image" LP679 melt down and UP700 smoked! After the repair I got image but no back light. Trouble shooting no back light. UP800 / swapped BKLT_EN_R 1.8v BKLT_SD 12V "not pulling down" Resistors checked. QP800 tested / swapped. power rails present. I have Isolated...

U8100 was damaged due to water damage. I did not find CPU shorts but who knows. No water under U8100 but damage to a few caps in the area. Unit would not engage 20v I pulled U8100 in an attempt to split ball it which was unsuccessful. So I need a replacement. I don't trust the one I have...

Just thought I would share this info for the board. I worked on a apple M1 Air today that came in for a cracked screen. Unit would not switch to 20v. Pulled the heat sink and looked under thermal and discovered the PMIC for the CPU U7700 was getting hot on the bottom center section...

I have seen this problem on air boards so I figured it was just the 5v missing. It wasn't. so I diode tested against my reference board L8502 and L8503. Readings were a little high compared to my reference board. .7 instead of .5 so I replaced U8502 and that didn't work. Just to be sure...

They suck! between T2 failures, and CPU failures I am about to give up and fix something else. Am I just stupid? Are you guys having the same kind of luck I am? It seems like I just take them apart. Total them and put them back together while making "FN ZERO $$$$$$$"

I put this one away after a few hours. Unit had water damage and a PP3V42 short which I repaired only to find out that the "click" does not work on the track pad. I have to use a external mouse. I thought the track pad probably got wet so I pulled the glued in battery and the track pad...

This was a liquid damaged machine but no liquid damage was on LB. Left ports were replaced. The left USB-C ports do not communicate USB data but do charge the unit. None of the zener diodes are damaged on the data lines and the fault covers both left ports. Looking at the schematics I see...

I get a quick bounce about every 3 seconds. rails are good no shorts on cpu/pch charge resistors are good. I do get a cpu_vcore good signal. Using the scope I do see data activity on bios but it's very brief and not normal. it starts the read but does not pull full blocks. I have no problems...

I have verified the power rails are present. unit sill not recognize on board HD. No shorts, no hot spots, All the SSD rails are normal. My next option would be to pull NANDs and test. Question before I start that. Can I replace these? Is there some magic apple drama preventing me...