1. Your PS2 reads games on DVDs but will not read games on CDs
2. Your PS2 reads games on CDs but will not read games on DVDs
3. Your PS2 will read no games, you have already cleaned the laser and you are using undamaged discs
Do not adjust the voltage if:
1. You do not receive the message "Disc Read Error" in the browser screen when trying to load problem discs
3. Your PS2 only gets errors on certain CD or DVD games, not All CD or DVD games. Try cleaning the problem disc, or using a Disc-Doctor
4. You receive "error reading CD" during games such as GTA3/VC or other games that stream data (clean the laser in this case)
please note that fine tuning may be needed if your PS2 reads CD games but not audio/PS1 CDs (or vice versa)... Or if your PS2 reads DVD games but not DVD movies (or vice versa)... Personally I don't suggest fine tuning without a voltage meter.