Got a MacBook Pro 2019 (A1989) (820-00850) that boots fine so long as it's powered from the power adapter.

On boot into macOS the battery shows as not charging, and needs servicing. Laptop runs slow, benchmarks are all 50% of expected.

Diagnostics reports a battery issue (PPT006) but also a potential SMC issue (PFM006).

Battery has 46 cycles, though went un-used for 2 or 3 years.

Trying to determine if I should go ahead and replace the battery in the hopes that's causing all the issues or if actually it's the other way around and the...

Re: MacBook 12" A1534 820-0244: No Backlight

I think I [I]may[/I] have identified the issue. The D8401/D7701 diode has a forward bias voltage drop of 0.205V matching a known good board of 0.210V however the reverse bias is 0.742V when it should be high/OL which suggests to me this is a shorted diode? U8401/U7701 is then refusing to boost as a result of seeing this on BKL_FB?

Does that seem like a plausible failure mode here before I get to replacing that diode?Re: MacBook 12" A1534 820-0244: No Backlight

I think I [I]may[/I] have identified

Got a MacBook 12" 2016 here that outputs to the display but has no backlight, can see the screen with a flashlight. Tried with a known good display and no change.

Measured PPVOUT_S0_LCDBKLT as 0.82V, and narrowed down the issue to something around Q8406, PPBUS_SW_LCDBKLT_PWR is 8.7V but output PPBUS_SW_BKL is 0.82V (should be 8.7V).

This looks to be because LCDBKLT_EN_L is high (8.63V) and thus the input isn't being passed through.

On trying to look at LCDBKLT_EN_L I see it comes from U8401, passing through R8402.

Here EDP_BKLT_EN/BKLT_EN_R...

Re: New Members - please post your introductions here

Hey everyone! New to the forum and new to Mac repairs but going straight into the deep-end which has turned out to be a more fun experience than expected.