Laser azimuth adjustment
Laser adjustment is one of the issues of the day as v3s and NEO2.2 v4s begin to expire when DVD-Rs are booted. So I asked my famous "mate round the corner" to brief me on the detail and here's what we've put together for you (updated with diagrams).
I've highlighted this paragraph because it will help make sense of everything else. The light wavelengths involved with CD/DVD are in nano-meters. No CD/DVD is manufactured so that the centre hole is exactly in the centre and that the CD/VD is exactly flat. The deviation will always be more than a DVD wavelength. So the laser 'floats' - that is to say as it follows the minutely wobbling and pitching groove, it reads the reflected light coming back, merging part of it with it's own beam and measuring the phase difference, the result being applied to an algorithm that tells the laser to adjust in either plane. With CDs it is far less critical and a single collecting diode is used to measure this deviation. With DVD there are four diodes that examine the pahse difference of the reflected light so that much tighter adjustment can be made as the groove is followed.
The laser assembly is mounted on a sled (see picture) which runs on two round steel runners. The azimuth adjuster screw - the one on the left side of the assembly) will tilt the assembly slightly by lifting one side off its rail. Experiment shows that the potential range of adjustment is very large; normal CD's and DVDs will read reliably over several turns of this screw.
However, DVD-Rs and CD-Rs exhibit a very different range of adjustment. DVD-R is most critical due to its much shorter wavelength. When Sony set the machine up originally, the setting was probably made with a 'standard' DVD because this (and CD) was all the machine was ever going to play .
Now that we are using CD-R and DVD-R, this adjustment is much more critical. Proceed as follows, with the PS2 already open - at your own risk of course:
1/ Carefully remove the top of the CR-ROM drive, four small screws.
2/ Power up and eject the drawer. Don't look into the laser lens, infra red is invisible and can cause retinal damage (it's probably safer to switch off when the cover is off the drive).
3/ Put a tiny drop of white correction fluid (or similar) on the screw to keep track of its position. You can feel how 'loose' the screw setting is by holding that side of the sled and seeing how much play there is. (This 'play' is deliberate, the screw must NOT be
tightened up so that the sled cannot move.)
4/ Put an 'iffy' disk (DVD-R) in the drive. Put the drive's cover back on, no need to fit the screws, a small coffee mug stood on top will suffice. See how good the 'boot' is.
5/ Eject the disc, remove the cover and move the screw clockwise a little. KEEP A NOTE OF WHAT YOU'VE DONE. Try again. Be
patient. Once you have found the position where boot will not happen, go the other way and find the other 'no go' end of the range.
6/ Keep going until you have a range of positions (probably less than half a turn) where the boot is best. Set the screw in the middle of that range.
7/ Verify that normal DVDs and CD still work OK. They should work, probably even better than before (if you'd notice).
CAUTION: If you tighten the screw up tight then the sled will not be able to move and you may damage the sled motor or mechanism
ONE FINAL POINT: Look closely at the diagram and you'll see grease on the rails. That needs to be their in order to keep things running smoothly and to prevent friction effects.
