Ps2 Magic 3 Problem
 

I have a problem with my ps2 magic 3 system It plays some ps2 games and it don't play ps1 backups is there anything that I need to do.

Not sure. Did you install it yourself? If so, I would go back in and check your work. What good are PS1 games these days anyway? he he

Are you following the boot procedures? like this:

NOTE: This is with the disk assumed in the tray and the tray closed:

Playstation 2 Games

• Power up normally from STANDBY with RESET button. A single tap is required.

Playstation 1 games & DVD Movies

• Power up from STANDBY with RESET button held until the blue EJECT light comes on; then release RESET and the disk will boot.

This is just a copy and paste from BGs "PS2 Boot Procedures For All Mod Chips!"
You should check that out.