[FUBAR] LB 820-2879 B no green or orange light (needs SMC)

[Mac-N-Sauce]

So I have PP3V42_G3H on the one wire circuit coming through pin 1 of C6908 and other areas. How do I know if i have a bad U6901 vs a bad via?

 

[dukefawks]

Got 3v on ADAPTER_SENSE? Have you tried another magsafe board?

 

[Mac-N-Sauce]

No 3v on adapter sense, tried a known good magsafe

 

[Mac-N-Sauce]

In diode mode i have .545v on pin 4 of u6901

 

[dukefawks]

Is there 3V on pin 1 and 4 of U6900?

 

[Mac-N-Sauce]

No, its not getting through

 

[aprendiz]

U6901 Pin 1 and 2 should have 3.3v from SMC_BC_ACOK, this voltage cames from CHGR_ACOK pin 14 of U7000

 

[larossmann]

I uploaded a few pictures from a diagram to try and make this make more sense. This was hastily put together at 2 AM in MS paint while half asleep, so try not to make fun too badly..

edit, pievce of shit cut out half of my pdf. let me fix this

 

[larossmann]

I uploaded a few pictures from a diagram to try and make this more obvious. This was hastily put together at 2 AM in MS paint, so try not to make fun too badly..

 

[larossmann]

and here's the rest

 

[rany]

I love this ^....

 

[JorgePayar]

and here's the rest

Wow, this is gold!! thank you Louis

 

[Mac-N-Sauce]

Ok, I have 3.9v CHGR_ACIN BUT AM NOT GETTING PIN 14 CHGR_ACOK. Had some bad capacitors C7020,c7021,c7022 also bad q7085. replaced all of them. Still have no 3.3v on pin 14 of U7000. Looks like other voltages are correct. could it be a blown U7000?
Have not replaced it yet.

 

[Mac-N-Sauce]

By the way, thank you so much for describing the path. that helps a lot. I was working on the Q7085 side not the other one. I couldn't get voltage through the Q7085 so I replaced it, then I was able to track voltage down to resistors, to the U7000 pin 27/28 CHGR_CSI_P, CHGR_CSI_N, CHGR_AGATE
PIN 1 = 14.8V, PIN 2 = 16.65V, PIN 26,27,28 15.95V

​I still don't have the right voltage on pin 14

 

[Mac-N-Sauce]

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[Mac-N-Sauce]

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Appears to be soda on the bottom of board. Other side had very little if any.

 

[rany]

Am I wrong or is ISL a bit prissy?

 

[larossmann]

the chip has more load on it than anything else since PPBUS_G3H powers the entire machine, and it also has to deal with knockoff chargers and ripple on PP3V42_G3H as well as its own issues when there's water.