820-4924 missing PP5V S4

[laptopcity]

Hi ive got an 820-4924 board which had liquid damage, no green light so so replaced u7100 and r7110 and now have charger light but no fan spin, check power rails
PPBUS_G3H = present
PPBUS S5 HS COMPUTING = present
PPBUS S5 HS OTHER5V = present
PPBUS_S5_HS_OTHER3V3 = present
PP3V42 G3H = present
PPVRTC G3H = present
PP5V S5 = present
PP5V S4 = missing so ive measured at u8060 where pp5v_s4 should be and p5vs4_en isnt present at pin 2 but when i go looking for that i cant find where it is made or comes from, am i missing the obvious ??? , i must admit i do get a bit confused as to what power rails are needed for the board to be turning on

 

[aprendiz]

Always post voltages, not only if it is present or not....

P5VS4_EN comes from PM_SLP_S5_L --->R8115 and so on...

 

[laptopcity]

Sorry about the voltages would have made more sense, yes should have said, i see it comes from PM SLP S5 L (i knew what i meant ,guess id had a long day) but i cant see where PM SLP S5 L comes from, thats the only place on the schematic for it

 

[dukefawks]

Where was the liquid damage? Is the board power cycling, check for short pulses on 5V_S4 preferably with a scope as with a multimeter will be hard/impossible to see cause pulses are very short.

 

[laptopcity]

Hi Duke all the liquid damage was around u7100 and u3090 but also looks like the ssd has some too, im afraid i dont have a scope , did try with the meter but couldnt detect anything , would be willing to order a scope if you think it would make my life easier

 

[dukefawks]

This could be anything really. Check U1900/U1950 for corrosion and possibly crap under the SMC. Did you check all other rails for short to GND?