In order to play games that were burnt using a computer and other types of unofficial software, a PlayStation 2 gaming console had to have a mod-chip soldered onto its main board. This process is called "chipping" your PS2. If you are purchasing or inheriting a used PlayStation 2 and would like to see if it has been chipped to play burnt games, there is a very easy way to tell.
Unplug all power cables and controller cables from your PlayStation 2. Turn the unit around so that you can see the back.
Examine the "Warning" label on the back of your Sony PlayStation 2. This warning label is in place to let you know that opening the case on your PlayStation 2 voids its manufacturer's warranty. If this label is spit in half, this is an indication that your PlayStation 2's case has been opened up, potentially for the purpose of installing a mod chip. If the label is intact, it cannot play burnt video games as no mod chip has been installed.
Use a screwdriver to pry open the case of your PlayStation 2. The case is made up of two portions -- a top portion and a bottom portion. The screwdriver will separate these two portions, allowing you to pull the top half off of the bottom half. Set the top half aside and look at your PlayStation 2's motherboard. Examine all of the equipment on your PlayStation 2's motherboard. If a mod chip is present, it will be a small, square chip with a label indicating exactly what it is. It will also have been soldered onto the motherboard after it was originally manufactured, so it will look out of place. If no mod chip is present, your PS2 cannot play burnt games.