820-01987 20v 0.019A pp3v3s5 pulsing

[posarah]

Hi all,

Need some assistance with a 1987. History is its chassis was completely crushed trackpad and screen were shattered not sure how but it seems like it was ran over. Board visually seems fine doesn’t look warped no visible cracks in anything board side.

went through the power sequence diagram on logiwiki for the 01055 because there doesn’t seem to be one for the 1987? All rails up until pp3v3s5 are present. Found out that pp3v3s5 and pp1v8s5 are coming on when you first connect the board but they shutdown after around 15 seconds or so.It seems like the PMIC is detecting a short on a minor sub rail and shutting down.

so the question is are there any signature faults with the PMIC and the 820-01987? Unfortunately I do not have a thermal camera so I’m hoping there’s a shortcut I can follow. Freaking seeks have gone from 500 to 900 hence why I’ve been putting it off, not to mention we don’t do much of this so it’s hard to justify spending a grand for a once in a blue moon job.

thanks for the assistance!

 

[posarah]

Has anyone else noticed the board view labeled 820-01987.bvr doesn’t seem to match the board? Been looking at the PMIC lines to see what could be shorted and a lot of the component locations don’t match the board. Especially test points.

Noticed 3 test points are reading as ground when they’re supposed to be PMIC outputs. One in particular p1v1_slpddr_socket_en. I’ve attached a pic with the 3 test points reading as ground outlined. Not sure if there the right test points though as they don’t line up with the BV.

 

[2informaticos]

Test points figured on the boardview are not always available on "real life".
It happens on other models too; even old ones.

Is the machine recognized in DFU?
Did you check diode mode to ground on all coils?
Apart of S5, can you detect any S3, or S0 voltage?

I suspect broken trace/solder, or knocked off components.

 

[posarah]

Think my USB C meter is trolling me. Disconnected power from it a few times and it was still stuck on 5V. Switched orientation of the power in cable and it went back to 20V than I disconnected the board and reconnected and it sat on 5V for a while till I went back to the original orientation. Time for a new USB c meter, freaking China!

I am getting ALL_SYS_PWRGD & SMC_PCH_SYS_PWROK for a brief moment and PLT_RST_L is 0v consistent so it's stuck in a reset state.

 

[2informaticos]

Did you test the board alone on the desk?
It should boot with correct charger.

Must be recognized in DFU, if T2 required AWAKE and SLPS2R voltages are stable.

 

[2informaticos]

Why will need you USB-C meter to confirm boot?
Measuring CPU core voltage is not good enough?

Is worth to force DFU mode.
Check SOC_DFU_STATUS, to get an idea about actual board state.

 

[posarah]

I managed to get our A1708 onto the latest OSX through legacy core patcher so I'm going to try forcing the board into DFU mode. For Apple Configurator though has Apple Configurator 2 been replaced with just plain old Apple Configurator? I can't find 2 on the app store and googling it there's forums pointing back to use plain Apple Configurator but all the DFU tutorials call it 2 so I'm not sure if I've downloaded the correct version.

 

[posarah]

Dfu restore failed (yes I know it deletes data that’s what I wanted).

 

[posarah]

It’s now saying apple controller instead of dfu. Tried it again and got a different error this time

 

[posarah]

Ha I feel like I'm the pin ball at a roulette table. Tried putting the board in DFU mode again and now recieved error 75.

 

[posarah]

Finally seems to of gone through now I’m at a lock icon?

 

[2informaticos]

That looks good.
The target MacBook didn't boot?
Still pulsing voltages?

 

[posarah]

It didn’t boot no, 20v fluctuates around 300ma didn’t check the rails had to head home. took the board and chassis home with me to try out it back together over the weekend but I forgot to grab the charger,multimeter and screws. Might try hookup the battery flex tomorrow and hold down the battery flap see if that boots otherwise I’ll have to wait till I’m back in the office on Monday.

 

[posarah]

It's still doing the same thing. ALL_SYS_PWRGD comes up to 1.8V for about 20 sec when the boards taking 0.5 amps than once it dips down to 0.01 it drops out. Do these require a battery to boot or complete DFU restore? I was originally doing it board only and kept getting -75. Read Logiwiki and it mentioned trackpad and battery must be connected but I didn't have the battery ribbon, so I just connected trackpad and that's where I got the above lock screen. I've got the flex now so is it worth putting the board back in the chassis and connecting battery and TP to retry DFU?

 

[2informaticos]

Yes, try DFU with battery connected too.

 

[posarah]

Looks like the CPU is dead . Connected the battery and trackpad and it would refuse to be detected in DFU mode despite the detect signal being present. Disconnected the battery and trackpad and connected the fan because I noticed the CPU heatsink heating up slightly and now can't get past 5V 280ma on all ports besides the trackpad side one way the connector gives 5v 280ma, the other way the board does not turn on at all, XAVbus fuse near the corresponding CD is 0v and the board takes 0 amps. Tried without my USB C meter as well to make sure that wasn't trolling me again than checking the fuse near the CDs to check whether it's 20V or not and there still 5V.

Checked the CD3217 LDOs all of them seem present, so either the ISL has gone or me leaving the battery connected for a while to charge up killed something.

 

[2informaticos]

You don't get PPBUS_G3H now?

 

[posarah]

PPBus at F7000 is 1.28V for about 40 seconds then the board shuts off and obviously drops to 0. That's if I reset the charger and it's at 5V. If I use another device to switch the charger to 20V than connect the board sits at 0.0035 ma and 20V which looks like DFU mode but it's not, DFU status is not present.