[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

 

[larossmann]

Where was the original damage on this board?Dead U7000 is possible but we need some better history here.

 

[Mac-N-Sauce]

No Title

 

[Mac-N-Sauce]

No Title

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

 

[larossmann]

If CHGR_ACIN is present and CHGR_DCIN is present and the resistance between pins 27/28 and pins 17/18 adds up to what the sense resistors' sum is, I would say time to replace U7000. Stay away from SI7149DP that thing is always fine, you can dip it in battery acid coca cola cat piss and beer and light it on fire and it will still work!

 

[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.