[Arakon]

pin 2 constantly sends out a signal, and at 5V no less, while most components in the ps2 run off 3.3V, including the laser. that damages the laser sooner or later.
before using caps became common, there were ALOT of ps2's with failed laser units after installing the chip.
the safest way for a neo 2.2 is this: a 100 V 1 uF cap on pin 2, and a 220-270 ohm resistor behind that, to smooth and lower the signal, so the negative effect is minimal, but the signal still enough to work.