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820-3476 Missing PM_SLP_S5_L (Quarter fan spin)

MOberdick

MOberdick

New member
So on this wine damaged board... I have pp3v3_s5 and pp5v0_s5 rails but PM_SLP_S5_L is missing on u8170 causing it to be unable to enter into S4 state. PP3v42 is present and I have charger light. I narrowed it down to something near U1950 I believe which has 3.42v on pin 8 and 0.19v on pin 2 (CPUVR_PGOOD_R) but nothing on any of the other pins. Can't find any shorts anywhere, its just not getting power. So far I have replaced U7200 from a chip off of a doner board but still has same symptoms.. am I missing something? I feel like the answer is right in front of me somewhere
 
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dukefawks

Administrator
Is PP5V_S4 pulsing? Measure carefully it may only pulse once after you connect power. Pulses will be very short and hard to catch on a slow multimeter. Preferably use a scope that has a much faster trigger than a multimeter.
 
MOberdick

MOberdick

New member
dukefawks said:
Is PP5V_S4 pulsing? Measure carefully it may only pulse once after you connect power. Pulses will be very short and hard to catch on a slow multimeter. Preferably use a scope that has a much faster trigger than a multimeter.
Click to expand...
pp5v_s4 jumps to 5.13v briefly while the fan starts to spin and disappears when the fan stops.... U1950 looks fine. I removed it but no signs of corrosion or damage underneath
 
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dukefawks

Administrator
ALL_SYS_PWRGD also pulsing? What is the pulsing voltage on Y1905, if over 1.6V U1900 is dead. Check if all power rails are coming high. CPU voltages are of course not there.
 
MOberdick

MOberdick

New member
ALL_SYS_PWRGD is at 3.3 now and the fan is spinning consistently? Not sure how this could have happened as I havent done anything since my last comment... I guess I'll plug it back up and see what happens
 
MOberdick

MOberdick

New member
So theres no display on the screen but I appear to have entered S0 state now from what I can tell. I think there may have been a cold joint under U1950 and when Louis asked to look under it and I put it back on it fixed the problem. Right now PP3v3_s0 intermittently cuts in and out occasionally.. troubleshooting more..
 
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MOberdick

MOberdick

New member
So I've gone back and started testing some of the rails listed below:
PPBUS_G3H -> 12.5v
PP3V42_G3H -> 3.44v
PP5V_S0 -> 5.13v (but it jumps around ocassionally)
PP3V3_S0 -> 3.3v
PP1V5_S0 -> 1.5v
PP1V05_S0 -> 1.05v
PPVCC_S0_CPU ->1.69v

Everything seems pretty normal but im still not getting an image on the screen. I started measuring around the backlight circuit and noticed EDP_BKLT_EN .. LCD_PSR_EN... and EDP_PANEL_PWR all have 0v on U8330.. any ideas?
 
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