820-3209 Turns on but no MagSafe light. PPBUS is at 8.17V

bjf

Member
Not sure what's happening with this. It was submitted as liquid-damaged but I'm not seeing anything. The fan goes high right away. Sometimes the fan will start and stop and then it turns on. Has flashing folder, but no MagSafe light. I've checked everything I could think to. Not sure what would causing this. Could it be a sensor circuit?
 

2informaticos

Administrator
Staff member
8.17V means no communication between SMC and ISL6259.
Check voltage and diode mode on SCL/SDA lines of battery bus.

Disconnect LIO flex and try to get correct PPBUS_G3H first.
When is done, check U7000/01 chips for SYS_ONEWIRE circuit on LIO board.
 

bjf

Member
Diode mode is measuring good at .501 and .502 on SDA and SCL. Voltage is measuring 3.4V on both lines but there's no signaling. The voltage is just staying fixed at 3.4V - no drops at all. I disconnected the flex cable but can't get PPBUS to come up. It stays at 8.17V. When plugging it in, the fan doesn't spin for about 5 seconds. It then goes high immediately after starting up.

The board is completely clean with no sign of any type of damage. The LIO board and cable are both known-good. I have a good 3209 board that I use for testing. I made sure they were both working on that board. SMC_ONOFF_L is measuring very low at .070 in diode mode. Not sure what would be causing it to go low like that.
 
Last edited:

2informaticos

Administrator
Staff member
That is your problem.
SMC_ONOFF_L is not good and board starts in SMC bypass, as above mentioned.
Disconnect trackpad flex and see if SMC_ONOFF_L has good value.
 

bjf

Member
I removed the entire trackpad connector as it was loose for some reason. That didn't change anything so I'm assuming I'm just down to a bad SMC. Won't be spending the time to switch the SMC so this is going in the as-is stack.
 

2informaticos

Administrator
Staff member
Very strange, you don't even want to check why SMC_ONOFF_L is low.

There are other reasons, apart of bad SMC, which can pull down that signal.
 

bjf

Member
I thought I looked at them all. I of course would like to look at other reasons. What ideas do you have? I've pulled everything on the SMC_ONOFF_L line and it's still there.
 

2informaticos

Administrator
Staff member
Did you check if R5070 is OK.
You can even force it to 1K and see what happens.

After trackpad is disconnected, remove U5110.
If still low, only SMC remains...
 

bjf

Member
Yes, that's where I had gotten the other day when I gave up. I had already removed U5010 with no luck. And checked everything else in the circuit with no luck. Letting this one go. Thanks.
 

2informaticos

Administrator
Staff member
SMC can be reballed with solder paste in aprox 10min.
I don't mean to reball the original; but you can try even that.
You should have scrap 00165 boards to pick another SMC...
 
Top