PS1 games do not run on the PS2?

fu
- in PlayStation
2

I bought a used PS2, because I once again fancy the old games. I still have some PS1 and PS2 games from before.

Now I have the following problem, the console does not read the old PS1 games. With one exception: Tekken 3, but all others do not work. I can remember earlier when I owned a PS2 when all PS1 games were running. I've already researched something on the internet and they all write that the Playstation 2 should read almost all games. What this list also confirms:

https://en.wikipedia.org/...yStation_2

All games and also the console itself are in very good condition and we also tested the PS2 of my friend - the same result: The PS1 games are not running! We also tried audio CD's - they're up and running. This would probably exclude a defective laser. So why is it and how can I fix it?

I would be very grateful for helpful answers.

Ka

In what condition are the discs of the PS1 games?

fu

They are also in very good condition.