820-00165 PP3V3_S4 shorted

[Instafixx]

PPBUS is 8.6V
PP3V42 is 3.4V.

No Fan Spin.
Around 120 mAmps drawing on the PSU.

Board was very dusty. Cleaned it .

Corroded Caps around R2021. Replaced.

Upon random checking found PP3v3_S4 shorted.
C2950 looked weird so removed that. Still the short is present.

Please advice how to proceed

 

[2informaticos]

You can use voltage injection method.

 

[Instafixx]

U2800 getting very hot. Can that be the issue ?

 

[2informaticos]

Is bad, if gets hot.
Board can boot without it.

 

[Instafixx]

Removed U2800.
Short is gone.
Put back C2950.

But still no Fan Spin.

PP3V3_S4 is at 2.9V

PM_SLP_S4_L is also missing.

 

[Instafixx]

1. PPVRTC_G3H	3.3V
2. RTC_RESET_L	3.3V
3. PCH_SRTCRST_L	3.3V
4. PCH_INTVRMEN_L	3.24V
5. PCH_DSWVRMEN_L	3.24V
6. PP3V3_S5	3.3V
8. PM_DSW_PWRGD	3.42V
9. PP3V3_SUS	3.3V
10. PM_BATLOW_L	3.3V
11. PM_RSMRST_L	3.3V
+1. PM_PWRBTN_L	3.4V

THE 11+1 LOOKS GOOD.

 

[2informaticos]

"PP3V3_S4 is at 2.9V"
Change U8000.

 

[Instafixx]

Replaced. Now PP3V3_S4 is 0V. it spiked once to 3.3V but then 0V.

S4_PWR_EN / PP3v3_S4_FET_R is 0V as well.

 

[Instafixx]

Replaced U2800 again. Still the same. Some corossion under U3210. Cleaned that too. Its still the same.

 

[2informaticos]

I said board boots without U2800.
Why wasting time replacing U2800, before getting image?

PM_SLP_S5_L goes high?

 

[Instafixx]

I am sorry i replaced U8000 again. Not U2800.

 

[Instafixx]

PM_SLP_S5_L is 0V

 

[2informaticos]

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.
If catch it, check for pulse at PM_SLP_S5_L (at same time).

 

[Instafixx]

Yes there is a drop at PM_PWRBTN_L and there is a spike at PM_SLP_S5_L

 

[2informaticos]

Then you should note pulsing S4_PWR_EN and 3V3_S4 too.

 

[Instafixx]

Yes. these pulse too when SMC_ONOFF_L is triggered.

 

[2informaticos]

You may have pulse on other power rails too.
Check on big coils also.

Tried SMC bypass?

 

[Instafixx]

Put back the board on the chasis.

When i press the power button. L7130 / L7520 / L7560 Pulse.

Tried SMC Bypass.
Battery Removed. Pressed the Power Button and connected the charger . Held the button for 10 Seconds - No Fan Spin.
As soon as i leave the button i get a 2 second fan spin. Then if i again press the power button i get a 2 second fan spin.

Now whenever i press the power button i get a 2 second fan spin

Should we reball the smc ?

 

[2informaticos]

Which other coils pulsing (in SMC bypass)?
L7130 pulsing for sure, not stable???

 

[Instafixx]

L7130 is stable. L7560 is stable.

L7430/ L7630
L7310 / L7320 / L7520

these are pulsing.

L3095 and L7701 are 0V.

This pulsing is when On/Off key is pressed.