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820-3115 missing PM_SLP_S4_L and 10 cent fan spin??

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Punkedthis

New member
Got this laptop from a guy i knew. Most of the water corrosion is around lvds and thunderbolt area, around u7400, all over dc in area, and smc looks pretty ok as well as the RTC clock chip which looks fine. First time I powered it up, green light and quater fan spin. Then I look around RTC area and looks clean but after I plugged it back in, no more spin and stays like that. So i decided to went ahead and replaced U2600 and I double check all my RTC power on R1800,1,2,3 but it's all there so no progress.

What is present and what is not:
All the rail is present in order down up until PP5V_S3_REG

Actions taken:
I followed the pp5v_s3 to where it's created and took me to u7200. Master EN pin 13 is present 3.44v
Entrip 1 is not present the down the rabbit hole started.
Q7221 is the mosfet controlling the enable. pin 6 is nothing but on pin 2, is 3.46v. like it's not passing through the n-channel mosfet...? I check traces, continuity and everything is just fine and dandy on that little area...

But anyways I followed up where P5VS3_EN_L was created and PM_SLP_S4_L was missing but pp3v42_g3h_reg is present. Further down to the cpu which makes the PM_SLP signal

U1800 on the (IN) side

-PM_SYSRST_L (0.0v)
-PM_PCH_SYS_PWROK (0.0v)
-PM_PCH_PWROK (0.0v)
-PM_RSMRST_L (0.0V)
-PM_PWRBTN_L (3.47V)
-SMC_ADAPTER_EN (3.44V)
-PM_BATLOW_L (3.30V)
 
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Punkedthis

New member
if you don't mind duke, a light low reading like ppbus_g3h (ex) PPBUS_G3H should be 12.8 but instead, on F7040 i get 12.44v what does this indicate? Is it a voltage drop that something along the line something is pulling it or.....am I just a over exaggerated prick? ALSO the same as PP3v42_G3H, it's supposed to be 3.42v but on L7220 i get 3.31v ......
 
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dukefawks

Administrator
What does PP3V42 have to do with L7220?

Seems like SMC is alive as there is 3V on L7220. This could be anything, corrosion under SMC is probably a good first suspect.
 
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Punkedthis

New member
Yeah I heat the SMC up twice with a crapload of flux and reflo good but seems like its the same. Guess I'll poke around u7200 for now
 
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Punkedthis

New member
dukefawks nada... nothing on both end. BUT on pin 1 of L7260 it's pulsing from .0001 to .0002 back to .0000....Sorry for the late reply. I'm still working a full 40 hrs job while doing this on the side.
 
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Punkedthis

New member
but while waiting, I'm going to go ahead and post up U7200 pins readings...
pin1: 0.0v
pin2: 0.0v
pin3: 1.99v
pin4: 3.31v
pin5: 2.03v boosting to 2.04v
pin6: .77v
pin7: 3.31v
pin8: 3.31v
pin9: 7.62
pin10: 3.31v
pin11: 3.31v
pin12: 0.0v
pin13: 3.44v
pin14: 1.99v
pin15: GND
pin16: 12.44v
pin17: 5.04v
pin18: .08v
pin19: 0.0v
pin20: 0.0v
pin21: 0.0v
pin22: 4.53v
pin23: 0.0v
pin24: 0.0v
 
Last edited:
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dukefawks

Administrator
Stop wasting time around U7200 it will be fine. Many multimeters are too slow to catch the pulse on L7260. Either use a scope or use a LED with a 1K resistor. The LED is fast enough to see it flash in a dark room.
 
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Punkedthis

New member
Luckily just have just that in hand. will give it a shot. I know you're busy with 10,000 question everyday but with this pulse, what is the reason behind it if I do get a pulse compared to if I don't get a pulse? your reply will be much appreciated. I'm working on the led and resistor on a wire at the moment.
 
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dukefawks

Administrator
What am I looking at? I see a LED without a resistor and some wires. If you connected the LED straight to the 5V supply it will be dead now.
 
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Punkedthis

New member
no power on either side on pin1 and pin 2 and I turned off the light for complete assurance and nothing is cycling through the LED.
 
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Punkedthis

New member
while I'm not able to do any readings at the moment due to work, I will check to see if PCH even turned up on s5 mode which I believed is this rail -pp5v_SUS_PCH and this is the only S5 rail I see for PCH so if this is present I'm going to crossed out PCH as the fault as it's actually doing something and probably moved on over to SPI ROM . I think this is the right path...at least I would hope so.
 
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