Cannot read PS1 Games??!!

Hello and thank you to everyone who is reading this in attempt to help me!

I have a unmodded v9 ps2. A few months ago, I received the disk read error on my ps2 and just decided to try and fix it last week. I did all the normal things, cleaned laser, adjusted voltage, adjusted laser height, and none of that helped. As I was sadly putting the ps2 back together I noticed something about the ribbon cable that connects the laser to the system board. The very end of it, that connects into the laser assemly, the gold contacts were scratched, ans scratched bad! I ordered the part, and it arrived 2 days ago. I carefully took apart the ps2 and replaced this cable. When I put it back together, I tested GT4, and it read the disk with no problem. I tried putting in a PS1 game, and it gives me a disk read error. I tried the same ps1 game in a buddies ps2 and it worked. I tried 4 to 5 more ps1 games that I had, and none worked. All my PS1 games have the black bottom on the disk. Anyway, can someone please help!?? I need to read ps1 games to use the HD MC trick! Please Help, any advice is much appreciated!!

you probably adjusted the cd laser voltage too far or not enough or you messed with the white cog which in turn will mess up the angle of your laser.

I know that I put the white cog back in place, as I marked it with a marker. Not sure about the voltage of the laser though...

I'm not sure if I used the multimeter right though...Can you explain how to get the voltage? And what the voltage is supposed to be for the left and right one? THANKS!

imo its never a good idea to adjust the voltage. you may only extend the life of the laser for a short time. And if you dont know what your doing you will kill your laser.

Lol, not quite the response I was hoping for...but...thanks? I think I can find the correct voltage for the laser pots...

does it play audio CDs? or PS2 CDs (NOT DVD)?

Hrmm....not sure, I am currently at work, I can test that when I get home, I'm assuming that it will not be able to play anything that is not a DVD, but I am not for sure. Still need some guidance on using a multimeter if anyone knows how.