YAY - my 6 year old Playstation is good as new!
1 - 2 horas
After my PS3 was 5 years out of warranty it finally broke on me. :(
I looked up the problem, and the first gen PS3 has a particularly common problem when it breaks, it's usually to do with overheating, indicated by the "Yellow Light of Death" YLOD.
Unlike the X-box Red Light of Death, the yellow is far more uncommon and much easier to fix. ifixit provide you with all the stuff you need and a tutorial video.
The whole process took about 2.5 hours I think, but I was doing it quite slowly as I got distracted by a lot of stuff when taking it apart.
It was the first time I've ever really dismantled something valuable, so I was extra-cautious (probably too much) and spent a lot of time cleaning and basically just looking at all the parts that make up the awesome machine.
I had to use my initiative a lot to work out exactly what I was doing a lot of the time as the video is not a step-by-step, screw-by-screw anaylsis.
However, I am a complete novice and managed to do it pretty easily. It was actually significantly easier than I thought and will go into future repairs more confidently.
The video isn't all that informative (I suppose it can't be in order to be efficient), so I advice using a bit of initiative to work out what exactly you are trying to do with each step. There are a lot of screws, but most of them have signs once your inside and you can work it out after studying it a bit.
Also, I was recommended to heat gun both sides of the motherboard, i.e. heat one side, leave for 20 minutes, flip, heat, leave for 20 minutes.
Worked great. I would upload some photos, but for some reason the uploader isn't working.