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820-2915 Throttling, liquid damage

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Ryanlen2

Member
Hi everyone. I have this board that came in with liquid damage. Damage was around u7000, Q5300 area and U9500. I replaced ISL, Q5300 and resistors in that area as well as U9500 and components in that area. Machine turns on but is very slow to boot into OS and fans throttle high shortly after it is turned on though it doesn't seem to be overheating. When it does boot into OS everything is very slow. It does this on battery and/or on charger & trackpad/KB connected or disconnected. Thank you, have a good day.
 
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Ryanlen2

Member
Hey Duke. Ran ASD EFI. Got SMC IO failed error. (TC0D, TC0P, TP0P, TH1H, TH2H, TM0P) The area above the KB and TP connectors is warmer than the CPU GPU area. Thank you.
 
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Ryanlen2

Member
Hi. I got a few. I just reposted. Thanks.


* Is it safe to assume that with the multiple errors that the SMC needs to be replaced? But like I said, it does get warm above the KB/TP area.
 
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dukefawks

Administrator
Find what is getting hot, something is messing with the SMBUS for the thermal sensors. SMC is probably fine, it is something that is on the SMBUS.
 
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Ryanlen2

Member
Unfortunately I could not locate the problem. I have been all over SMBUS line. The only thing that I have right now is that pin 1 of U5570 does not stay steady 3.3 v. It jumps very vigorously between 3.33V and 3.26V. I have compared to another working board, and this does not occur. PP3V3_S0 is a steady 3.3V on other test points I have tried. PP3V3_S0 is steady on pin 1 of R5570. When I remove U5570 voltage on pin 1 is steady.Thank you. Have a good one.

*Replaced SMC just in case. Same result like you said.
 
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dukefawks

Administrator
If the KB and TP connector area is getting that hot you must be able to find which component it is. It is probably causing all the issues.
 
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Ryanlen2

Member
Yea... Though it seems warm in that general area (underside of SMC), there is not one thing that is actually hot. Ive been over everything. Alcohol will evaporate quicker on that area, but its broad and nothing in particular is "hot". Maybe this is just normal behavior and I was going in the wrong direction thinking otherwise. Sorry.
 
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dukefawks

Administrator
Diode mode on SMBUS_SMC_B_S0_SDA and SCL. Check corrosion around U5570, U5520. Check R5260/61.
Replaced U5570 with another?
 
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Ryanlen2

Member
Hi. Diode mode on pins 9 and 10 of U5570 is .486. Have already replaced U5570, U5520 as well as R5260/61. Thanks. Have a good one.
 
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dukefawks

Administrator
Data lines going to R5260/61. It is just to make sure we're dealing with the correct SMBUS. Shorting out those data lines will not cause more errors if they already have an issue.
 
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Ryanlen2

Member
Before I had a chance to shorting out lines the board stopped booting with trackpad plugged in. In the end I ended up replacing U5805 and D5802. Board no longer throttles. However, I now have a very quiet high pitch squeal coming from somewhere, almost like a feed back sound. Seem to be around the center of the board but Im not certain. Squeal seems to change pitch with fans motion. Any thoughts?
Thanks have a good day.
 
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