A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

[meantomatoes]

I'm new to board repair so bear with me. Just my luck that this is my first.

This board likely had work done before. It was probably ultrasonic'd because it's pretty clean. The SMC had its underfill removed so someone probably reflowed or replaced (doubt) it. Pictured: Near the SMC the traces of Q5490 for pins 4 (PPDCIN_G3H_ISOL) and 2 (PP_SLP_SUS_L) are somewhat exposed.

It's stuck in S5 and missing PM_SLP_SUS_L (shorted) although I don't think that exposed trace is the problem, may have been the last person being lazy for a reading? Anyway, is this a dead CPU? As I'm a beginner I don't have an oscilloscope

From other threads, I measured
PP3V3_S5
PPVRTC_G3H
PM_BATLOW_L
PM_DSW_PWRGD
PM_PWRBTN_L
SMC_ADAPTER_EN
PCH_SRTCRST_L
PCH_INTVRMEN
PCH_DSWVRMEN
PCH_INTRUDER_L
RTC_RESET_L
which are all normal afaik.

PM_RSMRST_L is 0 because PP3V3_SUS is 0, because P3V3SUS_EN is 0 and is short, but since EN comes from SLP_L through R8190 (0 ohms) is SLP the short and therefore the CPU? Or maybe a short trace?

Edit: I'm editing as I go along. I found that PM_PCH_PWROK is 0 but isn't short. I don't think this explains the SLP short though.

Not sure if this is related but S5_PWRGD is only 2v.

Also please give me tips in general if you're willing!

[meantomatoes]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

Not sure who came up with that rule but here's my second edit:

I think PM_PCH_PWROK is 0 because ALL_SYS_PWRGD is 0. Not sure why. Not short. So it's probably not an issue with U1950 as is common with this model.

[piernov]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

PM_PCH_PWROK and ALL_SYS_PWRGD are irrelevant when not even getting to DeepSx state.
S5_PWRGD should be 3.42V. PM_SLP_SUS_L should not be 0ohm to ground.
With issues on both of these and work done around SMC, SMC is the first suspect.

[meantomatoes]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

PM_PCH_PWROK and ALL_SYS_PWRGD are irrelevant when not even getting to DeepSx state.
S5_PWRGD should be 3.42V. PM_SLP_SUS_L should not be 0ohm to ground.
With issues on both of these and work done around SMC, SMC is the first suspect.

Hi piernov, thanks for replying

So should I try replacing or maybe reflowing smc? I don't have a donor board

Also thanks for the software in your sig! I've been using phoneboard

[piernov]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

Someone already tried to reflow it. If it didn't go well, the balls are probably damaged, so it needs to be reballed at least, and most likely replaced.
Either 820-3476 or 820-3536 can be used as a donor for the SMC.

But after that there may still be something else wrong with the board, since the issue right now could've been caused by the prior repair attempt and the real issue is hiding somewhere else…

[meantomatoes]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

Someone already tried to reflow it. If it didn't go well, the balls are probably damaged, so it needs to be reballed at least, and most likely replaced.
Either 820-3476 or 820-3536 can be used as a donor for the SMC.

But after that there may still be something else wrong with the board, since the issue right now could've been caused by the prior repair attempt and the real issue is hiding somewhere else…

Okay, thanks. It actually looks like some of the underfill stuff got under the balls. Will probably try cleaning and reballing but I need to get the stencil. Will report back

After removing smc SLP_SUS short should go away right?

[meantomatoes]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

Wait--after checking S5_PWRGD again it's actually 3.42 as normal. Not sure what I was measuring before...

So, short on SLP_SUS is either CPU, R1464, Q5490, or on P3V3SUS_EN etc. I don't see where it would be tied to SMC?

[piernov]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

My bad, I check the schematics and indeed SLP_SUS# doesn't go to SMC whereas all other SLP_S*# do.
You can remove Q5490 and R8190 and see if the resistance to ground on PM_SLP_SUS_L goes up.

[meantomatoes]

Re: A1502 Macbook Pro 13" liquid damaged 820-3476, orange light no power

Sorry for the slight necro but I wanted to update you. I removed R8190 first and found the short on PP3v3sus_en, which could only be U8020. SLP_SUS is now 3.3v, yaaay. The other rails connecting to U8020 are fine. I ordered a donor on aliexpress so hopefully it will have a working U8020 I'll post a final update once it arrives.