MacBook Pro 2014 Retina Power Cycling

[jasonr2000]

hi guys I have the above mentioned MacBook Pro 2014 Retina 13"

and its power cycling no matter what I do.

it powers on chime turns off does the same over and over.

I've checked voltages and they are going up and down the 5v one gets there then falls to 0v 3v3 also does the same thing goes up to 3v then falls off.


any ideas where I can check next ?

I did notice a slight bit of corrosion in the are highlighted in the image.

none of the water indicators have changed colour so I'm not sure how it got wet there but its a shame to let it go to waste as its in mint condition minus this problem.

I hope that helps

thanks

[mon2]

To me, the highlighted area looks ok but it could be my tired 4 eyes. Certainly apply IPA (alcohol) on this area to clean it up if you wish.

Any rail that is pulsing should be investigated for a shorted component. Remove all power. Meter in resistance mode. Measure the resistance to ground on the pulsing power rail and post each measurement. No power during these tests.

If there is a low resistance on the rail -> the current sense circuit will sense this and immediately power off the power rail and often, there is a 'chirp mode' on the regulator to allow for a retry so the cycle repeats.