820-3662 PM_SLP_S5_L power cycles

[it-solve]

I have this board which power cycles n PP5V_S4

PP5V_S5 - 5V
PP5V_S4 - power cycles
P5VS4_EN - power cycles
PM_SLP_S5_L - power cycles
SMC_S4_WAKESRC_EN - power cycles
PP3V3_S5 - 3.3V
PP3V42_G3H - 3.4V
PPVRTC_G3H - 3.3V

There is no visible liquid around SMC.
Also, how do you test these boards without the attached battery? Is there the easiest way than yanking the battery connector?

Thanks

 

[2informaticos]

This board should start by itself on charger only.

First try to start in SMC bypass mode; to discard any SMC sensor issue.
Check for short on all secondary voltages.

 

[it-solve]

Thanks, 2informaticos

SMC bypass power cycles as well, with the fan turning on and off as it cycles.

Probed for shorts around all coils and filtering caps. I haven't found any.
The lowest reading I've got was around these coils, which is expected I believe.
L7630 - PP1V05_S0_REG_R - 80Ohms
L7430 - PP1V35_S3 - 200Ohms

In SMC bypass mode, the heat signature (3* higher than ambient temp) is pulsing around U3900 - BCM15700. Not sure how it is related unless water corroded some pins underneath the BGA


SMC and battery charger are warming up, even if no battery is connected


Haven't run it through ultrasonic yet, perhaps should go on that now.

 

[2informaticos]

Check for pulse at all PM_SLP_Sx_L signals and secondary voltages.

ISL6259 works all the time charger is connected; no matters battery is present, or not.

 

[it-solve]

Thanks

PM_SLP_S5_L - pulsing - 3.3V
PM_SLP_S4_L - pulsing - 3.3V
PM_SLP_S3_L - pulsing - 3.3V

PP5V_S5 - 5V
PP5V_S4 - Pulsing 5V
PP5V_S3 - Pulsing 5V
PP5V_S0 - Pulsing 5V

PP3V3_S5- 3.3V
PP3V3_S4 - Pulsing 3.3V
PP3V3_S3 - Pulsing 3.3V
PP3V3_S0 - Pulsing 3.3V
PP3V3_SUS - 3.3V
PP3V3_S3RSS0_CAMERA - Pulsing 3.3V

PP1V35_S3 - Pulsing 1.3V
PP1V5_S0 - Pulsing 1.5V
PP1V05_SUS - 1.05V

ALL_SYS_PWRGD - Pulsing 3.3V
PM_PCH_SYS_PWROK - Pulsing 3.3V
PM_DSW_PWRGD - Pulsing 3.3V
SMC_RESET_L - Pulsing 3.3V - 3.42V

CPUVR_PHASE1-3 - Pulsing 1.6V

Let me know if any other voltages you may need?

 

[2informaticos]

Try it with both charger and battery connected.
Just put the board in the chassis and connect battery, no other devices...

 

[it-solve]

When the board only is attached to the battery, with a connected charger I get quarter fan spin. 1.28A is drawn to charge the battery. Went like this for a couple of minutes and no more fan spin.

When only on battery no fan spin

When only on the charger - 20mA drawn

 

[2informaticos]

Check all SPI Bus Series Termination resistors and their traces.
Try known good BIOS file, clean ME.

No liquid sign, but any history available?

 

[it-solve]

Yeah apparently was dropped in a puddle of water. But it seems like it was wiped off. No discoloration marks on the board

 

[huzeafa]

I suppose you are using an original 85watts charger , also you can try to get a charged battery , that is if you are using an after market charger

 

[2informaticos]

You can have accumulated crap under BGA chips.
Heat them with quality flux, just in case...

 

[it-solve]

Hi @huzeafa yes 80W charger on bench supply.
@2informaticos, any suggestions of which GBA chips to reflow? I ran it through the ultrasonic and reflowed U3900 with no luck.

Next will hit SMC.

 

[2informaticos]

PCH and SMC should be first to try...

 

[it-solve]

No luck here. Will have to give up.