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Battery is not detected. Green light on MagSafe

Hi All.

I have a green light on my MagSafe charger but the MacBook will not detect the battery. I have 2 batteries and another MacBook which I have tested the batteries in. Once charged up in the other MacBook the batteries are able to power my A1342. The batteries are still not detected though.

Judging by the fact that the batteries can power the A1342 laptop i’m guessing the battery SDA and SCL lines might have an issue. I have a schematic but no board view. Where should I be looking on my logic board for damage and what could the issue be? Looks like there may be some in line fuses on the SDA and SCL lines. I also see a SYS_Detect line but I think this just tells the battery its connected to a laptop.

SMC has been reset a couple of times and I have reset the PRAM for good measure.

Any advice would be great - I don’t think the system has any water damage although I haven’t always been its owner.

I have attached a screenshot below of the System Information application showing this issue in the Power tab.

O.

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What is your logic board number 820-? (four digits)

par

Hi Dan. The Logic Board number is 820-2877-B

par

You'll need the Project K87 'Scratcho' 13" MacBook A1342 - board# 820-2877 drawing# 051-8561 schematics and board views.

Search Google for the board number you should be able to find them.

par

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Review the schematics PBus Supply & Battery Charger page check the power MOSFET’s. I’m suspecting you have a bad one.

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Hi Dan.

I'll see if I can test the MOSFET's today. I would assume the most common mode of failure on these is for them to go short circuit. If this is the case should I just check for continuity between the drain and gate pins?

par

They can fail in either direction! Use the Diode test function of your DVM.

par

Thanks Dan - I will report back after testing the MOSFET's.

I just re-watched Louis Rossman's diagnostic video for battery issues and he mentions a couple of voltage rails I can check. The data line resistors on my board look ok visually but i'll check resistances and voltages when I look at the MOSFET's.

par

Hi Dan - sorry about the delay getting back to you. I was awaiting a new multimeter!!

I have tested all of the MOSFET's in the charging circuit and all appear to be good.

I have also tested the SDA and SCL lines from the SMC to the Battery. Im getting 3.42V on the pull-up resistors and no shorts to ground but it would appear the SDA and SCL lines are shorted together (measured at the battery connector with the battery disconnected). I'm only getting 12.3V on the F7040 fuse suggesting the SMC cannot communicate with the U7000 ISL6259... Should I try removing U7000 or do you think this is more of an SMC issue at this point?

I did attempt to measure the resistances of the R5280 and R5281 pull up resistors but my values seem off (1.15K - maybe because they're in circuit).

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Hey @oliver_m - Do you want some assistance in tracing damage on a1342 I have the components identified and their functions lines identified.

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Oliver sera éternellement reconnaissant.
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