A1706 no power

[students_t]

You should test changing U7800.

OK, I've swapped in the U7800 from my scrap board, and now the voltage for 3V0_G3H is up to 2.77 V. Still not 3 yet though. What do you think?

 

[2informaticos]

In such case, the problem may be PCH.
What about the other U7800's LDOs now?
Do you get 3V3_S5?

 

[students_t]

PP3V3_S5 at C7840 shows 3.36 V

C7833 (LDO3V, PP3V_PMICLDO) shows 0 V
C7836 (LDO5V, PP5V_PMICLDO) shows 0 V
C7837 (VINLDO3, PPBUS_PMIC) shows 13.11 V
C7831 (VDD5_VPROGOTP, PP5V_PMICLDO) shows 0 V
C7830 (VDDIO0, PP3V3_PMICLDO) shows 0 V

 

[2informaticos]

Check diode mode to ground on missing LDO lines.
You may have bad solders on U7800; or bad PCH...

 

[students_t]

I could certainly believe there being bad solders. I diode mode I get:

C7833 (LDO3V, PP3V_PMICLDO) shows 0 V and beeps
C7836 (LDO5V, PP5V_PMICLDO) shows 0 V and beeps
C7831 (VDD5_VPROGOTP, PP5V_PMICLDO) shows 0 V and beeps
C7830 (VDDIO0, PP3V3_PMICLDO) shows 0 V and beeps

 

[2informaticos]

Don't write "V" after diode mode readings.
That voltage is generated by your multimeter.
Avoid any confusion with real voltage readings; when charger, or battery is connected.

Beep doesn't mean always short.
Post exact resistance (ohm scale) to ground.

 

[students_t]

C7833 (LDO3V, PP3V_PMICLDO) shows 0.9 Ω
C7836 (LDO5V, PP5V_PMICLDO) shows 0.9 Ω
C7831 (VDD5_VPROGOTP, PP5V_PMICLDO) shows 0.8 Ω
C7830 (VDDIO0, PP3V3_PMICLDO) shows 0.9 Ω

 

[2informaticos]

I bet for bad U7800, or shorted solder balls underneath.

 

[students_t]

I tried removing and re-cleaning the contacts and then reattaching U7800. I now get the following readings:

Location	Diode mode reading	V
C7880 (PP3V0_G3H)	0.400	2.75
C7840 (PP3V3_S5)	0.322	3.36
C7833 (LDO3V, PP3V_PMICLDO)	0.380	3.31
C7836 (LDO5V, PP5V_PMICLDO)	0.001 beeps	0 V
C7837 (VINLDO3, PPBUS_PMIC)	0.368	13.11 V
C7831 (VDD5_VPROGOTP, PP5V_PMICLDO)	0.000 beeps	0 V
C7830 (VDDIO0, PP3V3_PMICLDO)	0.375	3.31

Maybe an improvement, but still with some shorted solder balls under U7800?

 

[2informaticos]

Did you check diode mode on these caps before resoldering U7800?

 

[students_t]

I only checked diode mode before resoldering on the ones that I mentioned on Saturday (sorry about the "V" here, just leaving it as quoted)—

C7833 (LDO3V, PP3V_PMICLDO) shows 0 V and beeps
C7836 (LDO5V, PP5V_PMICLDO) shows 0 V and beeps
C7831 (VDD5_VPROGOTP, PP5V_PMICLDO) shows 0 V and beeps
C7830 (VDDIO0, PP3V3_PMICLDO) shows 0 V and beeps

 

[2informaticos]

You didn't mention exact values to ground there.
Not always beep is short.

If you remove U7800, clean the pads and check diode mode on all LDOs.
You shouldn't get any short, or low reading.

 

[students_t]

OK, with U7800 removed:

Location	Diode mode reading	Ω
C7880 (PP3V0_G3H)	0.436	1– (no reading)
C7840 (PP3V3_S5)	0.321	1– (no reading)
C7833 (LDO3V, PP3V_PMICLDO)	1. (no reading)	1– (no reading)
C7836 (LDO5V, PP5V_PMICLDO)	0, beep	1.0
C7837 (VINLDO3, PPBUS_PMIC)	0.419	1– (no reading)
C7831 (VDD5_VPROGOTP, PP5V_PMICLDO)	0, beep	1.1
C7830 (VDDIO0, PP3V3_PMICLDO)	1. (no reading)	1– (no reading)

 

[2informaticos]

So you have short at 5V_PMICLDO; no need to check the same line on two capacitors.

Once U7800 is removed, there only remains few capacitors to check: C7631/5/6, C8016/25.
Remove them one by one and see when the short to ground disappears.
Inspect their solders first; maybe you just moved them.