This code is for the Philips PET724, so it has to be worth a try on your unit:
1. Open the disc tray
2. Press SETUP
3. Go to "Preferences"
4. Press OK
5. Press 212225
6. Press LEFT, DOWN
7. Enter region (0 = codefree)
8. Press SETUP
9. Close the disc tray
If that doesn`t help, you could try the one for the Philips DCP 750
1. Press SETUP
2. Go to the preferences page
3. Enter 9, 6, 5, 3
4. Select region
5. Press SETUP
I`ve not got these units or yours to try it myself, so use at your own risk, but posting on this thread to let others know if they work would be helpful :)