820-3462: Not powering up. Missing PP5V_S5

Hello
Have a 3462 that doesn't power up. Only corrosion found was on C1683 positive pad. Resistance is about 4ohms. Also MagSafe adaptor light isn't coming on. I've tried SMC bypass and it still doesn't boot. Below are measurements taken:

PPBUS_G3H - 12.3
PPVIN_S5_HS_COMPUTING_ISNS - 12.3
PPVIN_S5_HS_OTHER_ISNS - 12.3
PP3V42_G3H- 3.4
PPVRTC_G3H - 3.4
PP5V_S5 - 0
P5VS5_EN - 0

Any suggestion?
 

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So liquid sign on the CPU area; that's not good at all.
4 ohms could be correct value for VCORE, depending on CPU type; compare with similar board.

"PPBUS_G3H - 12.3"
Post diode mode and voltage readings on SCL/SDA lines of ISL6259.
Also post resistance between its pins 17/18 and 27/28.

Do you get 3V3_S5/SUS?
Post SMC_RESET_L, SMC_ADAPTER_EN, SMC_PM_G2_EN, PM_BATLOW_L, PM_SLP_SUS_L and the 4 RTC signals (page 17).
 
Sorry for the late response. Here are the readings

SMBUS_CHGR_SCL - 3.4 (diode mode: 0.5)
SMBUS_CHGR_SDA - 3.4 (diode mode: 0.5)
pins 17/18 - 4 ohms
pins 27/28 - 22 ohms
PP3V3_S5 - 0
PP3V3_sus - 0
SMC_RESET_L - 3.4
SMC_ADAPTER_EN - 0
SMC_PM_G2_EN - 0
PM_BATLOW_L - 0
PM_SLP_SUS_L - 0
RTC_RESET_L - 3.4
PCH_SRTCRST_L - 3.4
PPVRTC_G3_PCH - 3.4
SYSCLK_CLK32K_RTC - 32.78kHz square wave
 

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"SMC_PM_G2_EN - 0"
Looks like SMC issue.
Reball it first and change if no result.
Be sure first all resistors and trace around SMC are good.

"SMBUS_CHGR_SCL - 3.4 (diode mode: 0.5)
SMBUS_CHGR_SDA - 3.4 (diode mode: 0.5)"
Try to post relevant informatiuon.
0.510 and 0.520 could be write both as 0.5 but difference on battery bus should be less than 0.5%, think about that...
 
Yep, it was the SMC. Replaced the SMC after reballing the original.

Second question: if one of the fans was bad, would this cause the second fan to run high. The system isn't hot. I'm currently waiting on a replacement fan but wanted to make sure it wasn't something else that need fixed as well as replacing the fan. I did confirm that the fan was the issue.
 

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You could specify Ts0P error from the beggining.
That is trackpad temperature sensor, but the error could be generated by another device connected in the same I2C bus; like ALS, for example.
So disconnect webcam first and also check its connector for corrosion, or bent pins.
Next step, try known good working trackpad board/flex.
 
I checked the webcam connector for bent pins or bridged pins, none. I also unplugged everything and swapped the trackpad and cable with the same result. I pulled the board from the frame and check for anything out of the norm, all looks good. The left fan always start up at high speed. The right fan always starts at the normal speed then slowly ramps up to high speed. I've swapped the fan to confirm that it's not the fan that's acting up.

Wondering if the issue is with the SMC? Is there a way to check this?

SMBUS_GPUTHMSNS_SDA - 33.6Khz
SMBUS_GPUTHMSNS_SCL - 95.79K
I2C_CPUTHMSNS_SDA - 33.6k
I2C_CPUTHMSNS_SCL - 98.33K

And each of their pull up's have 3.3V.

Any other suggestions of signals to check?
 

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"I2C_CPUTHMSNS_SDA - 33.6k
I2C_CPUTHMSNS_SCL - 98.33K"
Always check diode mode (red probe at ground) on data lines; ohm scale only needed after very low diode mode readings.
Did you try known good RIO board/flex?
 
I2C_CPUTHMSNS_SDA - 0.482
I2C_CPUTHMSNS_SCL - 0.484

I currently do not have a spare RIO board or flex cable. As i haven't work too much with this version year, won't unplugging the RIO board and cable change the behavior of the board; meaning, won't the fast fan spin right after power up return to the slow ramp up if the issue was with the RIO board? The left fan spins really fast at start up (no ramp), whether everything is connected to the board or not.

Is it possible the issue is with the SMC that i got?
 

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Could be a problem with the airflow temp sensor, or other device connected on SMBUS_SMC_1.
Check Q5502/04 connections to U5570.
 
Checked Q5502/04 connections to U5570.and it was good. So went ahead and replaced the SMC. The board is now fixed.

thanks for the assist.
 
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