Please help crystal chips installs

[psxmodsuk]

Hi ive been giving 2 slim lines to chip for friends although i haven't chipped for a while i did loads of messiahs on the older ps2's and i am very confident soldering and chip fitting.
But this problem is doing my head in i had 3 crystal chips ive tried all 3 in both ps2's and i keep getting the same thing the cd with the new firmware loads and the firmware upgrades no problem but when i try and boot a dvd backup it go's to boot and then just stays on a black screen and trys to read the disc.
Its not a media issue as ive tried a backup burnt at 1X on ritek g05 discs and still the same yet it will read dvd movie burnt on the same discs at 8X both also read original games.
Ive check everything over time and time again and tried all 3 chips in both ps2's and the same thing if the chips taking the firmware upgrade and booting the firmware cd everything must be fine i just can't figure it out please can somebody help thanks very much
Gaz