MacBook A1278 main 820-2530b not charge, it turns on only with battery

[lazaro.089]

Re: MacBook A1278 main 820-2530b not charge, it turns on only with battery

I found the issue!

R7052 was open to 2.5Kohms. I'm thinking that, correct me if I'm wrong, that created a voltage between CSOP and CSON due to C7050.

That voltage was telling U7000 that there was a problem with battery charging current and that it should shut down.

[mon2]

Re: MacBook A1278 main 820-2530b not charge, it turns on only with battery

1) Good job !!

2) Can you post the schematic for your 820-2530b logic board? My database does not offer the 'b' version.

3) My 820-2530-A schematic shows that R7031 (CSOP) & R7047 (CSON) are used for the current sense for the battery rail.

So yes you have the right idea in that the voltage on CSOP should be very close to the voltage on CSON. The current sense resistor between CSOP & CSON is used to measure the voltage difference (drop) between these 2 points. Let us say that if CSON connection to U7000 was open then the logic inside U7000 will report 'excessive load since the voltage is much lower on CSON than CSOP' = too much current for the design to be working properly so for safety, shut it all down.

Ideally there should be a very little voltage drop between any IN / OUT contacts of a current sense resistor. The current sense resistor is always a small resistance so that it does not heat up (too much) when the circuit is operating normally. The designer of the power supply will select the resistor and know in advance the relationship between the current draw (load) and the voltage drop across the component. Again, open circuit = too much load = shut it down.

[lazaro.089]

Re: MacBook A1278 main 820-2530b not charge, it turns on only with battery

Sorry I forgot to mention that my board wasn't the same as OP. I had a 820-2936-B.

Here are the schematics and boardview for it.

[reset1986]

Re: MacBook A1278 main 820-2530b not charge, it turns on only with battery

Sorry I forgot to mention that my board wasn't the same as OP. I had a 820-2936-B.

Here are the schematics and boardview for it.

i just read now, i eventually replaced ic charge, islxxx,
with battery and power supply the pc works correctly, in the end I closed it