820-3536-A No s4 rails present, tant cap on PPVCC_S0_CPU balls coming out

[PhilipC]

Got this machine in with no history known but obviously someone has worked on it.
Green light but no boot, No s4 rails present
G3H 12.57 steady

C1031 had balls coming out and is measuring 70.5ohms to GND and 0.041v diode mode measurement
Dont have a donor board for it and none of my other boards seem to have this cap either and I cant find a source in the UK. Are there any substitutes?
And can I just remove it with hot air? was a bit concerned since it was next to cpu

Screw hole next to the cap had the wrong screw in it, but it wasnt screwed down and doesnt look like they penetrated the copper layer. in some areas the solder mask is still intact

 

[dukefawks]

Cap is fine. 70 Ohm on CPU Vcore bus means there is hope for the CPU. Inspect board closely for corrosion and fuck ups.

 

[PhilipC]

found some corroded pads next to smc repaired them all but no difference. Could this be a problem of corrosion under smc?

 

[dukefawks]

Yup this could be crap under SMC and 100 other things too.....

 

[PhilipC]

Reflowed SMC and RTC no change. PM_SLP_S5_L measures 0v is this supposed to be low? Cant find any more correded or fcked with areas.
Have just ordered a DC-in board it seemed a bit loose on the board.

 

[dukefawks]

Could still be crap under SMC. Are you using a 60W charger? 3V on L7560?

 

[PhilipC]

85W magsafe 1 and using a converter. (85W Magsafe2 is on the way)

Yes stable 3v on L7560

 

[dukefawks]

Still suspect and SMC issue. Check for corroded traces or resistors around it. Could still have crap under it and it needs to be pulled and reballed.

 

[PhilipC]

I already repaired 3 traces that were corroded around it that's all I could find the other traces that were corroded just went to the jtag.

Should SMC bypass work? it isn't doing anything

What are those vices for reballing chips called?

 

[dukefawks]

Reballing kit seems like a good phrase to search. If you have a scope check for pulses on S4 rails, many multimeters are too slow to catch a power cycling board.

 

[PhilipC]

I do have a usb scope i dont know if that will be fast enough but i'll give it a shot. Any specific rails?

 

[PhilipC]

I have found some preballed SMC LM4FSXAH5BB Would that be compatible? in the schematic it says the chip is LM4FSXAH5BB and on the actual chip it says LM4FS1EH5BB

 

[dukefawks]

No you need to use from the exact same board. Chip has firmware.