PSU voltage when testing Macbook boards

[Askaleto]

Hello macbook repair experts, maybe this is a dumb question, but on many macbook repair youtube videos, especially from Paul Daniels, I have noticed that voltage is always 18V. I can see that in addition to USB Chipmunk tester, one important indicator is current that board is drawing. But if nominal voltage from the original charger is 14.85V (also written at the back of Macbook Air A1466 for example), so it could be possible to use 18V without problem, but in that case, current is not a reference, because boards draw power, so, if input voltage is higher, it will draw less current. On the other hadn, on Rossmann's wiki, there are exact values of current that points to different faults.

So, is it safe to use higher voltages such as 18V even if original charger is only 14.85V? So in these cases, actual current that boards are drawing are less than specified in the wiki table. Is this correct?

 

[2informaticos]

When using lab PSU what prevents you to set the nominal voltage for that machine?

We usually use 85W for testing all the boards in the process repair; 18.5V is normal then.
For MacBook Air, the VD0R sensor can be triggered in such case, but this doesn't avoid the board to start.

If you want to follow a current profile posted on Internet, then use the voltage specified in that profile.
You can also take your time and create your profile, using nominal voltage of that board.
There will be current differencies, even for the same voltage; depending by CPU type and RAM size, for example.
You cannot expect the exact readings, nor even for identical model boards.