820-3262 with NO POWER short on PPVIN_S5_H5_COMPUTING_ISNS

elcapitan

Member
Hello Everyone, I have a water damage macbook that came in with no power. When you connect the charger to the computer without the battery I get a solid orange light but it never turns on. During visual inspection, I was able to find a really corroded capacitor (C7202) near the U7200 (ISL95286) area. I took some measurements near that area and noticed that the line PPVIN_S0_CPUVR_VIN was shorted to ground. I chased this line down on the schematic and noticed that this line was creared by PPVIN_S5_HS_COMPUTING_ISNS and this line was shorted as well. I tried injecting some voltage into this line to find the faulty component but I wasn't able to find one. My power PSU will consume 0.98 @ 0.6v. I have attached a image of the damage. what produces this line? Im stuck here

My measurements are the following
PPBUS_G3H 0.52v
PPDCIN_G3H 15.02v
PP3V42_G3H 3.40v
PP5V_S5 0.92v
PP5V_S5 1.10v
 

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dukefawks

Administrator
3262 is not a valid number.
Any high side FETs shorted? Check all coils for short to GND too and then check that coil for a short to PPBUS. I bet shorted FET in CPU power supply....
 

elcapitan

Member
Hey Duke, I decided to give this board another try. Hopefully I can get it working. The actual board number is 820-3662-A. As I stated previously, when you connect the charger to the computer without the battery I get a solid orange light but it never turns on. Atm, I have a short on PPVIN_S5_HS_COMPUTING_ISNS . What do you mean by high side FETs? Are you referring to the power fets? I check the power FET U8001 since it had a cpu line but it seems fine. Not sure where to go with this. Thanks!
 

elcapitan

Member
Measure from L7320 to L7130, what is the resistance? Also measure resistance to GND on L7320 and L7130.
The resistance to GND on L7320 is
1) CPU VR_PHASE2 1.4-6.4 Ohms
2) PPVCC_S0_CPU_PH2 1.4-6.2 Ohms

The resistance to GND on L7130 is
1)CHGR_PHASE 3.70-14.60 Ohms
2) PPVBAT_G3H_CHGR_REG 4.7-10.9 Ohms

Also, the resistance to PPBUS from pin 1 of L7320 is 3 Ohms and on pin 2 is 3.6 Ohms.

Thanks!
 

dukefawks

Administrator
I have no idea what you are doing. I am just asking the resistance from one coil to another. It does not matter which side of the coil as the coils are 0 Ohm. So your measurement on L7320 to GND cannot be different on pin 1 and 2.
 

larossmann

Administrator
Staff member
Let's just make this simple since this is what goes wrong on all of these boards. Remove U7310/U7320/U7330. If it turns on , 99% chance your CPU is dead. That is what goes wrong with most 3662 with corrosion on the edge.
 

elcapitan

Member
Let's just make this simple since this is what goes wrong on all of these boards. Remove U7310/U7320/U7330. If it turns on , 99% chance your CPU is dead. That is what goes wrong with most 3662 with corrosion on the edge.
Thanks Duke & Louis for your advice. I was able to remove the short on PPVIN_S5_HS_COMPUTING_ISNS by removing the mosfets U7310. U7320, U7330. The only crappy part is that the computer still doesn't boot up. It just shows me a orange with spinning fans. . I guess my CPU is dead. Right? I checked the voltage on this line "PPVIN_S5_HS_COMPUTING_ISNS " and I'm getting 12.52v.

Thanks,
 

dukefawks

Administrator
Well the FETs are shorted and the chance this killed the CPU is VERY high. So only continue if you have nothing better to do.
 

elcapitan

Member
Well the FETs are shorted and the chance this killed the CPU is VERY high. So only continue if you have nothing better to do.
How can I verify the CPU is dead? I'm pretty sure U7310 was causing the problem. It would be nice to give it all I can. Thanks for the help and guidance

Cheers,
 
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