820-2523 super strange problem

peterfixit

New member
2523 intermittent green light
u6990 shorted,
u6990 replaced with one from an 820-2877 (same pinout)
output pin 4 now is 3.42V
ppbus 12.61
i think the problem may be smc communication?
 

dukefawks

Administrator
Crap under SMC/around U7000? Known good magsafe board? SMC_BC_ACOK?
If U6990 was really shorted there would be no green light at all.
 

peterfixit

New member
smc clear, u7000 clear, known good, SMC_BC_ACOK 3.374V@R6929, agreed, changed adapters now have green light, no change to other symptoms
 

jadao

Member
Intermittent meaning green light stops randomly or it's blinking?

Since U6990 was shot, nothing funky in this area? D6990 and resistors.Traces for onewire circuit.
 

peterfixit

New member
there is no D6990 on this board, i think green light was the charger or dc-in board, but it didnt change anything
 

dukefawks

Administrator
You start the topic by saying no green light. Then it has a green light and ask for more advice? What is the problem, green light was fixed. Use 85W charger and need to short power pads on these boards.
 

jadao

Member
there is no D6990 on this board, i think green light was the charger or dc-in board, but it didnt change anything

Maybe another D6xxx label on this old C2D board. I don't have the schematic but pretty sure if you look pp3v42 power supply circuit you will find a dual switching mode diode. But if you fixed green light, it s not anymore relevant.

If intermittent green light is fixed, and you are using 85w charger and you short SMC_ONOFF_L pads or use a keyboard to power on the board and it still doesn't power on, then it's time to check further power rails.

What about C7771 output voltage?
 

dukefawks

Administrator
Since you changed the adapter, is it a REAL ORIGINAL 85W one? Battery charging? Does it power off a charged battery? Must short power pads on these boards.
 

peterfixit

New member
yes genuine 85w charger, no battery to test with but power at battery connector is 0.15v on ppvbatt, on q7035 i get 15v on input and 0.6v on output but is not shorted to ground, smc_onoff_L does nothing
 

peterfixit

New member
1.070V at c7771 I cant find TP[1]PM_PWRBTN_L, the tp doesnt line up with anything on the boardview , the only other places it goes is under the cpu and smc
 
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