820-00165 no green light SMC_RESET_L present

MexicoTV

New member
Hello all,

Am attempting to repair this board which has no green light. It has all the G3H "always present" voltage rails except that PPBUS_G3H is 8.1V. It is not going past this state and S4 and other voltages from there on out are missing. I can't see any shorts atm nor do i see an attempt at turning on and then shutting down because of a short. It just seems dead. SMC_RESET_L is 3.3v and the one wire circuit seems to be okay. I did have to cross ref the info for the LIO board where the one wire circuit is as I can't find the LIO schematic for this board.

Your help as always, greatly appreciated.
 

JohnB8812

New member
Tried another DC-in board/cable? History liquid drop etc? Sounds like corrosion under the SMC or bad SMC to me
 

MexicoTV

New member
Yes forgot to mention that I did try another DC in board and cable. Customer didnt mention liquid damage and I don't see any corrosion.
 

JohnB8812

New member
Either corrosion under SMC, bad SMC, or bad ISL6259 (less likely). Start by giving the SMC a nice light reflow be sure to remove the edge bonding well. If no change, replace from and identical 820-00165 donor board.
 

2informaticos

Administrator
Staff member
Not really needed schematic for LIO board to check SYS_ONEWIRE circuit.
Easy to locate the two 5 pins chips there.
Then compare with U6900/01 from 3115 board; or same circuit from available LIO schematic.
In fact, start checking voltage on Magsafe central pin (LIO board) and SYS_ONEWIRE line from MLB; you must get the same voltage.

8.1V points to SMC issue.
Disconnect LIO flex, keep only 5 pins DC cable connected.
Still 8.1V?
Try to reflow SMC, better reballing it.
 
Top