playstation 2 disk read error

Can someone direct me to a site that illustrates with pictures where the voltage control knobs on a playstation 2 are located. I need to repair my playstation 2 and the other method which involves adjusting the knob that controls the distance between the cd/dvd doesn't fix the problem.

You need to completely open up the system.

These pots are located at the bottom of the lens, they are 2 circular knobs, one regulates the DVD laser, and the other the CD laser.