820-00045 (A1534) Won't get out of S4/S5 state, no shorts, no damage

Fyo

New member
I'm troubleshooting this board that is in good condition, no liquids damage, no corrosion, no bad caps that I can see, nothing getting warm. Previous owner said it just powered off and would not charge. The board negotiates 20V from a PD charger. This is not a power-in failure.

I don't have an inline volt/amp meter for USB-C, so I continued by using a 5V Anker power bank (PD) and inline 5V meter to see amperage. There is no current draw, only a blip of 10mA every 15 seconds or so (without battery). With battery, the boards goes to 0.4A, shortly cuts out, then goes to 1.8A, which looks like it's charging fine.

Rails I have measured:
PPDCIN_E85_SS is 20V on PD, 5.1V on Anker powerbank
PPBUS_G3H = 8.6V
PP3V3R3V0_AON = 3.28V
PP5V_S4 = 4.995V
P5V_S4_PGOOD = 3.3V
PP3V3_S4 = 0V (70K to gnd, goes to 0.07V three seconds after plugging in power, then gradually goes to 0V in about five seconds)
P3V3_S5 = 3.3V
P3V3_S5_PHASE = 3.3V
PM_SLP_S5_L = 3.3V
PP1V2_S3, PP1V8_S3, PDDR_S3_PHASE = 0V
PPVCC_S0_CPU = 0V
PP1V05_SUS = 1.05V

Considering that P3V3_S5 is VIN for U8000 and PM_SLP_S5_L is the trigger, PP3V3_S4 should be 3.3V (but isn't). U8000 is not damaged.

I am aware of the CPU failures. This is a personal laptop.
Will be glad to look for more clues if needed.
 

Fyo

New member
Thank you!
Before I replace that chip, because it is a very small part, can I confirm by injecting external 3.3V into PP3V3_S4?
 

Fyo

New member
Optionally, can I bridge PP3V3_S4 and PP3V3_S5 to confirm U8000 is bad?
 
Last edited:

Fyo

New member
Yeah, but I want to confirm I get somewhere if PP3V3_S4 is high, in case I need to order any other parts.
 

2informaticos

Administrator
Staff member
You can try bridging, but this may not help.
Get scrap boards, is the best option for replacement parts.
 

2informaticos

Administrator
Staff member
Timings required on the power on sequence.
You cannot expect to complete the sequence bypassing some steps.

Replace U8000 and continue to check other things, if needed.
 

Fyo

New member
Could anyone recommend how to remove chips on these boards? I have never had so much trouble trying to remove a part.
I have one of those Chinese hot air soldering stations. I use it to reflow personally designed new boards, but I use leaded solder paste. 360deg C is usually sufficient.
I covered the area around the chip with kapton and tinfoil, used flux, 380deg but after 5 or so minutes, the chip won't budge.

Edit: I am thinking I could heat up the area at 300deg for a few minutes and then blasting the chip for as short as possible with 420deg.
 
Last edited:
Top