MacBook Pro Early 2015 13" 820-4924-A troubleshooting? No display, fan spin

[wyga]

MacBook Pro 2015 A1502, motherboard 820-4924-A suddenly stopped working. When I turn it on I got the full fan spin, however no display. What's strange when I plug in the HDMI cable with TV turned on MacBook shuts down, no more fan spin. Same goes for the thunderbolt.

I've checked the board for potential damage, no components burned, no shorts really. I have found out only Q3080 to be discoloured but that's just probably heat. I've checked the components related to Q3080, nothing shorted, on PPBUS 13V.

After few other checks I've found no voltage on C1031 on PPVCC_S0_CPU. Cpu definitely gets 1V.

Could it be dead CPU?

[piernov]

Re: MacBook Pro Early 2015 13" 820-4924-A troubleshooting? No display, fan spin

HDMI is on RIO board. You tried bare main logic board right?

After few other checks I've found no voltage on C1031 on PPVCC_S0_CPU. Cpu definitely gets 1V.

That's quite the contradiction here…

[wyga]

Re: MacBook Pro Early 2015 13" 820-4924-A troubleshooting? No display, fan spin

Yes, I have tried bare logic board without RIO board. Similar result, full fan spin and when connecting display through thunderbolt it shuts down. As soon as cable is unplugged or display turned off it kicks back in.

I've tried out of curiosity back then plug in something to the USB ports on RIO board, to see if that will shut it down. No issues with that. I feel like I am missing something

About the contradiction there, pardon me. I've checked components nearby 1V as far as I remember was present but on PPVCC_S0_CPU just 0V. I will get back to the schematics today to double check everything around.

[piernov]

Re: MacBook Pro Early 2015 13" 820-4924-A troubleshooting? No display, fan spin

If you're missing CPU VCore then you have to go through the list of power rails to see if you're missing anything else.