820-01598-06 Reboots and slow

[prodigy83]

My reference only: REF1131

Board has liquid damage.
Computer turns itself on even if I hold the power button down to shut it off. Just keeps turning itself back on.
There is no OS installed.
I try to run Apple diagnostics and it wants to connect to the internet, I type in the wifi password and it never connects, just spins.
The mouse and keyboard are slow/choppy. The fan does not spin fast, it does not spin up at all but from what I can remember, the fan would spin up after being turned on for a while.
Battery seems fine as I unplug the charger and the computer stays on.
Keyboard light is coming on.
I tried getting the computer in to DFU mode via the keyboard method and no success. (Not sure how to place in DFU mode without keyboard).
I am assuming this is a sensor issue but I have no clue where to look to be able to tell?

 

[2informaticos]

Inspect audio board/flex and touch ID for corrosion.
Check diode mode to ground on T2 data lines from J6600.

 

[prodigy83]

Flex and board look good.
I am not 100% certain which ones are the data lines, nevertheless T2 data lines? I am assuming the data lines are the ones with "SPI" at the beginning?
SPI_MESA_MISO_CONN: .494
SPI_MESA_MOSI_CONN: .516
SPI_MESA_CLK_CONN: .515

 

[2informaticos]

You should test in other shell, with known good TP/KB and touch ID.

PMU_ONOFF_R_L_CONN should stay high and drops only when press the power button.

 

[prodigy83]

I did confirm with another iCloud locked motherboard that the shell, everything is working fine.
I did however decide since J6700, the clip was damaged and I had been using kapton tape on top to make it snug. I ended up replacing the entire J6700 connector from a donor board. While doing so, I noticed pin 14 "I2C_KBD_SDA" the pad was damaged. Not sure if I did that or if it was like that the entire time. Anyhow I repaired the pad with a slug. But after doing so, I am experiencing the same result.
Just also checked for continuity from J6700 pin 14 to J6701 pin 8, and I do have continuity. What else could this be?

 

[2informaticos]

Try starting into diagnostic mode.
Machine allows you to boot USB macOS?

It should automatically enter DFU, if you reflash Soc ROM.

 

[prodigy83]

Try starting into diagnostic mode.

While holding down D, it takes me to the Starting Internet Recovery Screen, then it wants me to connect to the wifi. I type in the password for the wifi, and it just sits there spinning and never connects.

Machine allows you to boot USB macOS?

Well, when I hold down the Option key, it does detect the macOS image, I choose it, and then it goes back to booting from internet recovery, I get to the wifi password screen again, I type in the password, and it just keeps spinning.
I did get it to go in to DFU mode, so I did both a restore and revive, this did not help. Still need to do the Soc ROM? I tried googling for this file but I am not locating it. I googled "820-01598-06 Soc ROM" without the quotes.

 

[prodigy83]

Update:
J6700 voltages while running with the lid closed:
Pin 18= 1.7v
Pin 19= 0v
Pin 20= 5.1
Are we a bit low on pins 18 and 19 with the lid being closed?

 

[2informaticos]

Reflashing SoC ROM will not help, if already completed DFU without errors.

Something more has been affected by corrosion on the MLB...

 

[prodigy83]

C7652 pin 1 Is spiking up and down, 1.99v to 0v, there was burnt sides around this area. I take it C7652 is not supposed to do this? Bad U7650?
Replaced the following: C7691 This is spiking up and down too 3.2 to almost 0v, C7652, C7698, and R7695 all replaced.
I get 12.3v to 12.6v on Pin 23 on U7650.
L7030 is going from 12.3v to nothing up and down. The board never did this before.

 

[2informaticos]

Don't bother checking L7030 on these boards; is irrelevant.

Pins 19 & 20 are tied together at J6700.
Board stays on with PPBUS_G3H fluctuating 12.3-12.6V?
Check it disconnecting J6700.

 

[prodigy83]

Its not powering up now but I get a healthy 20v PPDCIN_G3H_CHGR up to the mosfet Q7030. I tried reflowing this but I think it may be bad?
I just removed L7030 to isolate the issue and pad 1 of L7030 jumps up and down from 2.1v to 1.6v.
Took up Q7030 also and pin 1 is up and down, its is looking like possibly U7000.

 

[2informaticos]

Why do you insist around L7030?
Do you see any direct connection between L7030 and PPBUS_G3H?
There is a buck-boost converter, not just a simple buck converter, like in old models.

If USB-C ports switch to 20V (without battery), then PPBUS_G3H and 3V3_G3H_RTC must be both OK.
Impossible scenario with bad U7000.

So do you get these voltages now?

 

[prodigy83]

Aha, sorry. I am used to the old power aliases.
The USB-C port does have slight damage but as long as I have been scewing down the connector plate, it stays fine at 20v. Upon replacing U7000 I do have 3 pads missing but they say NC, so I am assuming these don't matter. The pad numbers missing for U7000 are: F2, F3, and H4.
USB-C meter does show 20v.
PPBUS_G3H shows slightly up and down: 12.29-12.59
PP3V3_G3H_RTC is stable.
PP3V3_G3H is a problem, it drops from 3.3 to .9v.
PP5V_G3H_LDO is also unstable. U7650 problem?

 

[2informaticos]

When in DFU, PPBUS_G3H still fluctuates?

Compare diode mode readings on all big coils with known good board.
Cycling lower power rails can be caused by a short somewhere.