[CLOSED]820-3115, Liquid, Missing PM_SLP_S5_L

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SMMRepair

Member
Repairing this board for a friend, but looking more and more like a bad PCH. I want to make absolutely sure before giving him the bad news.

Board had liquid all over, 7+ areas. Replaced obviously bad components. PP3v42_G3H was shorted; found U7941 was shorted, replaced, and short on 3v42 was gone. Got green light. Fixed some burned traces in a few areas, and ppbus was very low. Replaced ISL, got solid 12.58v on ppbus. Now all S5 rails present (including S5_PWRGD), but PM_SLP_S5_L is not present. VRTC is present everywhere it should be, and PM_SLP_SUS_L is also present. Resistance to ground on L7630 is 7.6ohm.

Is there anything else I can check before declaring this board irreparable (I can't replace PCHs)? Thanks for any help.
 

SMMRepair

Member
Hey Duke,

Thanks. I replaced the clock, even though there wasn't really any liquid nearby, and no change. Voltage is present at all of R1800/01/02/03 and they all measure out properly (and there was no liquid near them, etc).

Thanks!
 

SMMRepair

Member
Thanks, Duke! Yeah I pulled the SMC and it was clean underneath; replaced it and same issue. I did notice, however, that I'm missing all T29 rails. I can't tell from the schematics, but at what point should these T29 rails show up? Is it after PM_SLP_S5_L? It seems they should be present at all times though, right?
 

dukefawks

Administrator
T29 is thunderbolt and of no interest. I have no more ideas then to check for corrosion, there is no easy solution.
 

SMMRepair

Member
Thanks, Duke. Yeah this board had so many areas of liquid that it's likely a through-board trace or something that isn't visible. Would take too much time; I'll call this one closed and inform my customer-friend, thanks!
 
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