u/Extension-Apricot187 — reddlx

Hi everyone,

I'm struggling to get backups running on my PS1 SCPH-7502 (PAL) using FreePSXBoot / Unirom (v4.1, BIOS 4.1, image E-318178bf).

The Setup:

I successfully installed FreePSXBoot on a Memory Card (Aliexpress) using a PS2 with FreeMcBoot.
Unirom boots up perfectly on the PS1, I can see the menu and the memory card content.
The console is NOT hard-chipped.

The Problem: When I insert a backup and try to boot, I get the error: "Not a valid CD or the drive is locked". I can hear the motor spinning (sometimes), but it doesn't seem to "grab" the data.

What I've tried/checked:

Laser Health: The console plays original Audio CDs perfectly for over an hour without skipping, so the laser seems healthy.
Burn Quality: I burned the games at the lowest possible speed (X10).
Cross-Check: The same burned discs and the same Memory Card (with Unirom) work perfectly on another PS1 that does have a physical Modchip.
Hardware: Tried placing the console vertically/upside down, but it didn't help. The disc doesn't even seem to spin up when I'm inside the Unirom boot sequence.

Is the SCPH-7502 particularly stubborn with the software exploit? Does it require a specific "swap" trick even with Unirom, or is my drive controller just refusing to unlock?

Any advice before I give up and look for someone to install a MM3 chip?

Thanks in advance!