A2141 820-01700-05 - No Power - Alternating 20vdc->5vdc

[selecttronix]

First post and long time viewer / supporter.

Have an 820-01700 A2141 on the bench that is scary clean and no previous repair attempts (Sudden Death). No signs of liquid exposure or accumulated dust corrosion.
Initially, it pulled 20v steady but amperage would climb from .2A and within 15-20 seconds make its way to .95A then drop to .01A. Process loops indefinitely.
Knowing how sensitive these T2's are, I placed it into DFU mode, that held until a revive attempt was made, then it disconnects within 20 seconds w/ error: AMRestoreErrorDomain error 9.

After the DFU attempt, the system now alternates between the initial 20vdc to 5.14vdc then back to 20v @ .01A.
20v stays for 6s and 5.14v for 20s.

Suspecting a NAND/SSD power issue, I checked SSD0 and SSD1 and both measured fine with 2.5v and no short to ground when battery is disconnected.
When battery is connected, it will stay steady @ 2.5v when 20v goes to 5v but right before it goes back to 20v, SSD0 & SSD1 drop to 0v for 3s then returns back to 2.5v.
Never seen anything like it.

PP_G3H - 12.6v while pulling 5.14v from USB-C then 12.76v while pulling 20v.
PP0V9_SSD1 - 0.88v
PP0V9_SSD0 - 0.88v
PP5V_G3S - 5.13v
PP1V8_G3S - 1.79v
PP3V3_G3H_SSD0_SNS - 3.38
PPBUS_HS_CPU - 12.6v
PPVCC_S0_CPU - 0.00v

PPVCC_S0_CPU - 2 ohms to ground which I think is normal with these newer CPUs.

Any help would be greatly appreciated. I know my way around the brd and schematics and can provide any test points needed.

 

[2informaticos]

First of all, welcome to the forum!

All the USB-C ports have the same behavior?
Be sure to use 96W charger; 140W even better.
This board doesn't turn on with 87W charger, if battery is drained.

Check voltages behavior with both charger and battery connected.
Also check diode mode to ground on all coils; compare with good board.

 

[selecttronix]

Much appreciated. First time with the 01700 and wasn't aware.
All 4 Type-C Ports produce the same results.
Ordered a 140w that will arrive Thursday and will post back updated results when it does.

 

[selecttronix]

New 140W arrived and is no longer alternating between 5v & 20v so thank you for that!

Have 19.7v constant now but amperage still starts at .42A then gradually makes it way to .97A then immediately to .01A (endless loop).

When I place into DFU and run Revive, it will get to step 4 of 4 with a progress bar that quickly goes to a 1/3 of the way and stops.
Seconds later, the letters 'DFU' on Configurator will go away leaving just the dotted box.
When this happens, the amperage will then alternate from .99A to 1.03A for about 30 seconds. After which, I receive the error 9 again and the amps go back to .01A to .97A. Configurator then goes back to it's default 'Connect Devices' screen.

Don't have a spare 01700 to compare with or that would help a ton.

PPBUS_G3H is now bouncing all over the place from 11.8v->12.30v->11.80->12.76-11.8v.
SSD0 & SSD1 will go from 2.5v to 0v about every 23 seconds, stay @ 0v for 3 seconds then back to 2.5v (endless loop).

PP3V3_G3H_T - 3.36V
PP5V_G3S - 5.14V
PP0V9_SSD0 - 0.89V->0V->0.89V
PP0V9_SSD1 - 0.89V->0V->0.89V
CHGR_PHASE1 - 12.V->2V->5V>12.1V
CHGR_PHASE2 - 12.V->2V->5V>12.1V
PP3V3_S5 - 0V
PP1V8_G3S - 1.8V
PP1V2_S3 - 0V / 146Ohms to gnd<--Doesn't look right in S5 state - Digging into that now

 

[2informaticos]

The data is probably not recoverable anyway.
You should try DFU restore.

 

[selecttronix]

Data wasn't an issue and tried restore with the same error 9. Tried new OEM Type-C Cable just to rule that out. Shouldn’t PP1V2_S3 be alive in off state?

 

[2informaticos]

S3 voltage can't be present in off state; nor even in S5.

Check voltage on the big coils when you note the amp increasing.

 

[selecttronix]

Anything in particular? The last voltages I posted were on the coils top side. The large coils for the CPU have nothing on them.

 

[2informaticos]

"PP3V3_S5 - 0V
................
PP1V2_S3 - 0V"
Only two and not sure if you checked them when amp increased.

BTW, no need to check L7030.

 

[selecttronix]

I did. Checked them all for 45 seconds with how it was ramping up just to be sure.
Been repairing 820- boards all the back to the 2011 Radeon 67XXM & A1466 Backlight IC disaster days and normally don't get stumped but this new board with new symptoms has me searching for the bourbon pre 5pm.

 

[2informaticos]

Flash SoC ROM and try DFU again.
Don't forget to make backup first.

BTW, do you note the amp increasing without battery connected?

 

[selecttronix]

Haven't messed with SOC's yet but will do my homework unless you can shine some light on the procedure and have the .bin.
What makes the backup?

When battery is disconnected, the board pulls no amperage.

 

[2informaticos]

Some details about dealing with SoC ROM.

820-00850-A - Tries to turn on and restarts

820-00850-A It tries to turn on appears the Apple logo and starts loading and the it crashs and keep in a loop Customer told that before brings to me it appears even the login screen and then crash Doing visual inspections the board looks fine Is it board issue or the disk is crashed and...

boards.rossmanngroup.com

A2141 T2 Unlock Data.BIN

drive.google.com

 

[selecttronix]

I don't have a WSON 3x4 Programmer w/ a 1.8V Adapter and the time required to get everything in, the client would have busted our doors down.
I'm going to call the time of death on this PCB, hold a viewing, and see if he's fine with sending it into y'all for possible resurrection.

PS, there are too many questions on this forum for just you to answer and provide detail. Louis needs to add a couple more smart dudes to take on the heavy load @ boards. as I would easily pay $100-$200 /mo for this forum service if it offered more detailed responses or even a 10 minute phone call with rapid fire voltage rail 'roll calls' and other misc test points to nail down the issue promptly.

With that being said, I do appreciate your time and wish you a great day.

 

[2informaticos]

The forum goal is to guide into repair process.
For online assistance, in a particular repair, Skype, Whatsapp and Telegram are preffered.