1 - 2 horas
My PS3 was aging and after four years I finally got the YLOD. Thought about getting a new one but decided it would be fun to take it apart and give it a try.
I followed the repair guide and videos step by step and had no problems.
I have the 80gb MGS3 PS3 so there was one minor part I noticed that was different than in the guide. The ground cable passes under part of the power box, so rather than taking it out first like the guide suggests, I had to remove the power box first. Not a big deal. Other than that just follow the guide and you should be fine.