820-02443 - No power 5V 0.010A

joesklar

Member
Hi there,

I have a faulty board. The meter is reading anywhere between 5.020 - 5.040V and 0.000 - 0.030A. The amp reading seems to suggest it is power cycling somewhat...

I tested U5700 and I'm getting the correct voltages. In fact I am getting PPBUS_AON.
Around U5200 PPDCIN_AON_CHGR_R I am getting only 5V. Does this suggest an issue with the CD32 chips?

I tested all USB-C connectors with the same readings.

Any help is appreciated!
 

joesklar

Member
I originally replaced the screen. Since replaced, sold on eBay. The customer returned it after 1 month, when I got it back it is in this state. There were no known issues with the board.

3V8_AON - 3.8V

I'm not sure what to probe around U8100. What is an LDO? If you can tell me what to test I can provide the readings.

Many thanks
 

2informaticos

Administrator
Staff member
Low Drop Output (LDO) rails are clearly marked on pages 42 (Master PMU) & 38 (Slave PMU).

BTW, don't bother with the ones marked "NC" (Not Connected)!
 

joesklar

Member
Thanks for the explanation!

Here are the voltages I think I have them all covered.

U7700:
PP1V8_S2 - 0.3-0.4V fluctuating
PP1V2_S2 - 0.3-0.4V fluctuating
PP3V8_AON_SPMU_ISNS - 3.8V
PP1V5_AON_VCORE_SPMU - 1.5V
PP1V2_AON_SPMU - 1.2V
PP1V8_AON_SPMU - 1.8V
PP1V2_AWAKESW_BLC - 0.0V
PP0V72_S2_VDDLOW - 0.140 - 0.170V fluctuating

U8100:
PP3V8_AON_MPMU_ISNS - 3.8V
PP0V8_S2_CLVR_VDDDIG - 0.200 - 0.240 fluctuating
PP3V3_AON - 1.7 - 1.9V fluctuating
PP1V8_S2SW_CLVR_VDDC1_LDO - 0.380 - 0.460V fluctuating
PP3V3_S2 - 0.9 - 1.1V fluctuating
PP1V2_S2 - 0.360 - 0.460V fluctuating
 

joesklar

Member
Hi,

PMU_VDDHI
R8170 pin 1: 12.340V, pin 2: 2.580V
R8171 pin 1: 2.580V, pin 2: 0.0V

U8100 diode mode readings
PP0V8_S2_CLVR_VDDDIG - 0.313
PP3V3_AON - 0.423
PP1V8_S2SW_CLVR_VDDC1_LDO - 0.517
PP3V3_S2 - 0.413
PP1V2_S2 - 0.294
 

2informaticos

Administrator
Staff member
2.58V at PMU_VDDHI is good enough; if you don't detect any drop on it.
I asked about its behavior just to confirm is is stable.

In this case, all U8100 LDOs should also be stable.
You may need to replace it.
 

joesklar

Member
Thanks for the feedback.
I have never replaced a BGA chip this large before. Even if I could perform the work, where can the chip be sourced from? Does it need to come from a donor board or can it be ordered online?
In your experience is specialised equipment needed or can it be done with a standard microsoldering set up?

Thanks
 
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