IMPORTANT: With the Laser Fix can you increase the life time from your PSTwo laser unit but WITHOUT any warranty!

Brief explanation :

The tracking and focus coils are driven by a power driver IC (the infamous LA6508 on V9/V10 and what seems to be a custom part on the V12) which in turn is driven by the PS2 CD/DVD controller. The voltage swing on the coils can sometimes reach some very high values causing some high current to flow thru them and in the long run this can lead to a dead laser head and/or power driver.

On V9 machines a common solution (the "Romeo mod") was to disconnect the 12v power line used to drive tracking / focus and connect it to 5v, automagically limiting the voltage swing on the coils. On the V12 PS2s this is no longer possible and a different solution had to be found.

This is the voltage behaviour on the tracking coils on a brand new unmodified PS-TWO

The Proposed Solution: "Laser-FIX"

Since the power driver IC is mainly a bunch of amplifiers with high current outputs, the output voltage is proportional to the input signal from the CD/DVD controller. By limiting the input signal to the power driver we can ensure that the voltage swing on the coils does not exceed a maximum value.
The input signal from the CD/DVD controller can be easily clipped to ~1.2v by using two special diodes connected to ground as from the following schematics.

The result of this fix can be seen on the attached images below:

TRACKING:

FOCUS:

The only problem we found that this fix doesn't address is the presence of a high voltage spike on poweron of PStwo which is not related to the input signals but is generated by the power driver IC during its bootup sequence. This will need to be investigated some more.

Anyhow we belive that this fix should already highly reduce the risk of a dead laser into the PS-TWO.

Additional info:

This fix can also be applied to V9 / V10 machines as a replacement of the "Romeo Mod" if wanted.
However this will not protect the laser from an LA breaking down and driving the coils with an higher than normal voltage, so for the old machines the power line reduction is probably still a safer solution. Just for reference you can check the result of this fix on a V10 PS2 here:

Laser fix on V9 / V10: