A1502 Macbook Pro - powering on issue

[chrisaw]

Hello there!

So here's the deal - I'm not a shop but upgraded anyway to get a swift and useful answer on this.

I have an old Macbook Pro which has a strange issue and I haven't seen this discussed on the YouTube channel so I'll try to describe the symptoms:

- The device powers on sometimes (typically after a long period of not being used.)
- The device does NOT power on every time on battery.
- The device does NOT power on every time on AC either.
- Disconnecting the battery for a long time (a week or two) and then reconnecting it almost always revives the laptop until it goes to sleep at which point it will sometimes turn back on again when opening the lid but typically will refuse to work for a while again.

Remedial action so far:

- Replaced the battery completely - this resulted in it working right away making me think it was resolved. Put it to sleep overnight, didn't wake up again the next morning.
- Replaced the AC adapter both with the same adapter model *and* with a spare 85W adapter I had laying around - no difference.

I do have a multimeter so am happy to test points on the board if that helps but right now I'm at a loss where to even start.

Thanks!

 

[2informaticos]

First of all, welcome to the forum!

Now tell us the 820-xxxx code of your board; like 3536, 3476, 4924...

 

[chrisaw]

Thanks for the warm welcome!

As for the board code - I've done some research but I'm coming up blank on how to actually find this on the board itself. Any tips?

Looked up the board for an 820-xxxx number but not seeing anything. The one thing I can tell you is that the EMC number is 2875 if that helps?

Thanks

 

[2informaticos]

Inspect the board corner near the right speaker and power connector for RIO board.

 

[chrisaw]

Thanks for that - 820-3476-A

 

[2informaticos]

Do you get 3V3_S5/SUS?
Post exact PPBUS_G3H voltage (F7140) with charger only.

Check all 4 PCH's RTC signals; RTC_RESET_L, PCH_SRTCRST_L, PCH_INTRUDER_L and PCH_INTVRMEN.
Also post PM_BATLOW_L, PM_DSW_PWRGD, PCH_DSWVRMEN, SMC_ADAPTER_EN, PM_RSMRST_L, PM_PWRBTN_L and SMC_ONOFF_L.
Be sure SMC_RESET_L is steady high.

We need to know these values when the board doesn't want to boot.
Check then if start in SMC bypass mode.