Spotlight of this week’s repairs is this A1990 Macbook Pro Not Turning On Repair. When we look at the Macbook, although it’s a 2018 model, it looks like it has just been bought new.
ITSolve Repairs specialise in Macbook Repairs in Adelaide
IT-Solve is the leading Macbook Repair Centre in Adelaide. Our workshop is equipped with state-of-the-art troubleshooting and repair equipment. We can identify and replace those failed individual components instead of the complete motherboard of the Macbook.
This was exactly what this user had been advised when they went to the Authorised Apple Repair Centre here in Adelaide. The quote was close to the replacement value of the Macbook. No wonder why more and more people just buy a new one instead.
Perhaps that’s Apple’s way of selling more Macbooks and generating more e-waste. But it is staggering the mindset damage it does to people. Who leaves Apple Genius Bar convinced that they need a new Macbook every two years!?
Locating Fault on A1990 Macbook Pro Not turning on Repair
When we connected the Macbook to our USBc meter charger, we could immediately detect that neither charging nor turning on circuit was initiating. The Macbook is stuck on 5V 0.02A. This tells us that the USBc chips, which are CD3215C with this model, are not negotiating the PD protocol. Either one or more of them is faulty. Alternatively, they detect a short circuit down the line and enter protection mode.
Later one is easier to detect and resolve, so let’s start with that. We can start measuring the fuses and big coils first, as they are on the major artillery lines.
A1990 Macbook Pro Not turning On – Identifying fault location
Straight forward, we located a dead short on the Macbook’s PPBUS_G3H line, this indicates a shorted component on this line. However, the PPBUS_G3H line is one of the most populated, and thousands of components must be hanging on this branch.
An easier way to locate it is to disconnect the PPBUS_G3H line from more sensitive parts of the circuit by lifting up the fuses and injecting voltage into the line.
By following Ohm’s law, with such low resistance, we should get a component emitting heat when under stress. With thousands of components populated so densely on this board, it’s almost impossible to detect 60-70*C heat by touch. So we rely on our IR Temperature Camera to detect minor heat disturbances.
Long gone are days when fuses would blow or magic smoke escaping would indicate where the blown components were. Especially with short circuit protection on chips and constant current sensing lines all over the place, they all go into protection mode when there is some disturbance in the force.
A1990 Macbook Pro Not turning On Repair Process
We located and replaced the shorting capacitor, which seemed to draw all that current through itself. Hence it was glowing like a bulb.
Looking at the USBc meter now, PD protocol communication is achieved and provides 20V as expected.
The next step is to check quickly before we assemble for further tests. Once it turns on and all seems fine, we can go ahead and assemble it.
Successful A1990 Macbook Pro Not turning On Repair
Running all diagnostics yielded a successful result. So we were good to go and test the remaining of the system.
After a couple of hours of testing, we could see the repair was successful, so we could inform the customer.
The root cause of A1990 Macbook Pro Not turning On Failure
In final words, this Macbook was barely used for anything else than a media system. Most likely with a closed screen on a desk connected to a media system, if we had to guess. Considering that it has such a powerful GPU and CPU – it emits lots of heat. Although it was not much dusty inside, the closed system generated lots of heat which could not escape quickly enough. Add on that prolonged streaming they tend to heat and stress those filtering capacitors on the logic board.