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DFU didn't help. but I did find corrosion on: PPV4V9_VPMUP_SPMU on C7752. cleaned it up and replaced the cap. The 5v is present. This 4v9 rail hit PP1V8_AWAKE through C7790 next to it. That runs to U7700 so I am sure that chip is gone. It also runs to ROMs and a bunch of other stuff...

I did find some corrosion VPUMP_SPMU cap that goes to U7700. That 5v is still present. They are going to try DFU later today. I will update this thread. What is VPMUP-SPMU anyway? This is apple silicone so I cant find information on it.

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?

I have successfully moved GPU chips. I just encountered one of these same problem but have not moved the GPU on this model yet. We shall see.

I have one of these. 25v on pin 40. Trying to figure it out. Tried a test screen. Still no back light. Has image

I have one of these too. It lets me select startup options then after a few seconds flashes a purple screen for 1/20th a second and resets. DFU nothing works. Must be a core RAM issue or something on the M1. I have seen a few of these M1's die for no reason at all. I just reflowed the...

Well I am totally stumped on this one. UP800 gets the 1v8 enable. Does not enable QP800 12v remains high. In my experience this will stay enabled even if there is a failure with the FET and the buck is shut down. I have replaced UP800 twice just to make sure. "all sources are donors"...

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...

not even a twitch on the scope. light only.

no data activity at DP_INT_HPD external USB drive does light up

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"

Battery was good. Totaled the machine. Probably a CPU driver or something. Too intermittent to repair.

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...