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820-01949 - No signs of life- 20V, 0.07A.

R

ronaldo

Member
Hi, everyone. Need help, please.

Die suddenly for no reason.
The logic board is very clean.
When connecting in AC2 it shows straight in Recover mode.
We tried to revive it in DFU mode and it failed.

LogicBoard stand-alone.
PP1V2_AWAKE - 1.2V
PP1V8_AWAKE - 1.8V
PP3V3_AWAKE - 3.35V

PP1V1_SLPS2R 1.1V
PP1V8_SLPS2R 1.8V
PP0V8_SLPS2R - 0.8V

PP2V5_NAND_SSD0 = 2.5V

PP3V3_G3H_RTC_REG_R - 3.3V
PPBUS_G3H - 12.6V
P1V8G3S_EN = 1.78V
P3V3G3S_EN = 1.8V
PP1V8_G3S = 1.8V

The only coil that has voltage are:
L7660 - P3V3G3H
L7600 - P5VG3S - 5.13V
 
2informaticos

2informaticos

Administrator
Staff member
What error did you get in DFU?
You should try restore too; will erase SSD!

Flashing SoC ROM is worth to try...
 
R

ronaldo

Member
I managed to back up the firmware from the IC, but I can't find another good firmware anywhere. Can you help me with that?
 
R

ronaldo

Member
Thanks for that.
This is for a different board. Does it work on 820-01949?
Also, do I need to change the Serial number?
 
R

ronaldo

Member
For some reason with the firmware that you gave me, it gets stuck on 5V.
I've reprogrammed it with the original firmware and it is back to 20V.
 
R

ronaldo

Member
This is what happens when trying to revive.

The System cannot be restored
on this device.
The operation couldn't be completed.
(AMRestoreErrorDomain error 6 - Failed
to handle message type StatusMsg
(Operation failed))
[AMRestoreErrorDomain - Ox6 (6)]
 
2informaticos

2informaticos

Administrator
Staff member
That's (almost) pure short.
Probably dead CPU; is the most sensitive component connected to that power rail.
 
R

ronaldo

Member
I removed the Current sensor R8118.

Diode mode:
PP1V1_S3 - 0 (2.2Ohms to ground)
PP1V1_S3_REG_R - 0.448
ISNS_CPUDDR_P - 0.706
ISNS_CPUDDR_N - 0.706
 
2informaticos

2informaticos

Administrator
Staff member
99% is CPU.
All remaining chances for a DDR chip; these are more resistant than CPU.

Just in case, you should detect something injecting 1-1.3V there.
IR cam can help you; need to remove CPU heatsink first.
 
R

ronaldo

Member
1.3V injected on PP1V1_S3 and only RAM modules are getting slightly hot.
All 4 removed and the short on the board is gone.
On the modules, the pins are shorted to the ground.
I will get new modules, replace them, and return here with an update.
 
R

ronaldo

Member
Coming back with quick update and asking for more help, please.
All 4 RAM modules replaced.
Same capacity, but different brand.
I had to move a resistor to change MEMORY CONFIGURATION STRAPS.
Originally it had a Micron Memory and I have replaced for a Samsung Memory.
R1331 moved to R1330 to fits the Samsung config according to the page 3 on the schematics (CPU DRAM CFG Chart)
U8100 – Replaced, just n case it gone faulty.

All setup is correct, Logic board is getting
20V – 1.9A with battery
20V – 0.07 without battery

L8100 – PP1V1_S3_REG_R
125.3 Ohm to ground
0.059 in diode mode

But still not getting PP1V1_S3_REG_R

Q8100
PPBUS_HS_CPU – 12.90V
P1V1_DRVH_R – 0V
P1V1_SW – 0V
P1V1_DRVL_R – 0V
P1V1_PHASE – 0V
 
2informaticos

2informaticos

Administrator
Staff member
Post U8100 basic voltages: pins 12, 6, 16, 17.
Be sure no short, or low resistance to ground on pins 1, 5, 9.
Check all its surrounding resistors.
 
Last edited:
R

ronaldo

Member
U8100
Voltage on pins.
6 – 0V
12 – 0V
16 – 0V
17 – 0V

resistance to ground
1 - 350 Kohm
5 - 411 Kohm
9 – 107.6 ohm

All resistors are fine.
 
Last edited:
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