Problem with my Sega CDX

[Tokimemofan]

Let say you have a ps3 right that play all ps1,ps2 ,and ps3 games. And it having problems playing ps1and ps2 games right but it can play ps3 games . see ps1 is formatted a cd-rom game right . Now for the ps2 games is formatted dvd right . If you have that problem it have to be the laser going out and needs to be replaced . Simple as that .

You are misunderstanding how these work, your PS3 example is misguided because a PS3 has 3 Laser Diodes either of which can die individually, a dead 780nm breaks cd-rom (Blue and Black discs CDs) 650nm breaks DVDs and 405nm breaks BluRay (and usually everything else as the ps3 starts it in 405nm mode to check for the presence of a disc) The Sega CDX only has 1 laser. A laser failure also couldn't cause the black screen problem. Check and make sure the bios is good and original, some people like to put a region free bios in these things, if such a mod is done wrong it would cause this as could a lifted pin on any of the surface mount IC chips. It is likely to be a hard to ID failure since there are not many simple problems that would still allow the Genesis and Walkman modes to run while disabling the bios completely. The symptoms are similar to a model 1 that had 4 lifted pins on one of the cpus. Get out a good magnifying glass and inspect every connection on both boards.
Edit: Another note, The BIOS will run without a laser assembly even being present, something I tested when part swapping to ID a broken part on one I had.