Even if the CD motor is bad, it should play through the start-up screen (with the shattering Saturn logo & sound and all that). If you're not getting any of that, and it just dumps you right to the CD menu screen (as if you had the cd-tray open), your console's connections to the CD assembly itself maybe a bit loose.
This is a maybe, but does it do any of the following?: 1) make light "popping" type noises on the menu, 2) the polygons on the lower corners of the CD-menu are look all blown up. (the polygons that move around and changes sizes with the music when any music CD is being played).
If it does any of the above, definitely open up the console, and check and readjust the white ribbon cable that goes from the motherboard to the CD assembly.
Try that out and see if it helps any.
If that doesn't help, you'll most likely have to replace the whole laser assembly itself. I do have a couple extra mk1 laser assemblies & I'd sell you one cheap, but shipping from Canada to UK would probably cost 2-3x more than what I'd charge you for the unit itself.
I brought it down from the attic and plugged it in. It cycles through the logo then goes to 'checking disk format' and hangs. The cd mech doesn't spin the disk and the access light does not flash. On the dashboard, what's normally the two floating cubes are big splodges of red and yellow, right and left respectively.
No matter how much you think the world revolves around you, you'll always be just a character in someone else's story.
If it goes through the start-up screen like it does normally (with sound and animation and all that), then the connection between the motherboard and the laser assembly is probably okay.
If that's the case, it may be that laser eye itself may be worn out and weak to the point where it can't recognize that there's a disc in there. Your saturn will tell the motor to spin only if it recognizes a disc in there.
In this case, the last thing I might try is adjusting the potentiometer on the laser eye. If you open up your unit and look below the laser eye (looking at it from the rear part of your system), you should see a white (I think) plastic screw. That adjusts the intensity of the laser. Try adjusting one way or the other, in about 20 degree increments or so, and see if it'll spin the disc. If it does, then you should be able to squeeze a little more life out of that laser assembly.
If that still doesn't work, then the motor that actually spins the disc is probably shot, and in such case, the easiest solution is to replace the whole assembly itself.
Try it out. You don't have much to lose by trying.
I think she's dead sir. I've spent the last half hour or so adjusting the potentiometer incrementally to no avail. Oh well - nothing ventured, nothing gained as they say. You can normally pick up another machine for buttons, so I'll just keep my eye out for another mk.1.
Thanks for the suggestion, though.
I meant to add that I don't get the animated shattering logo screen - it just goes straight to the Sega Saturn front page and the sound is VERY muted.
Yeah, if there's no sound/animation on the startup screen, then it usually means that the motherboard doesn't "see" the laser assembly at all. That's usually due to either 1) the white ribbon cable that goes from the assembly to the board not being connected properly, or 2) one of the few other cables that come from the motherboard to the lower left hand side of the laser assembly isn't connected well. (For example, if you just pull out one of these cables out of a good Saturn and turn the system on, you should experience similar symptoms to what you're experiencing right now).
Anyway, if you checked those connection points already, then I'd be completely out of ideas at this point.