Sega CD Drive problems

[kcsims]

I have a model 1 sega cd and the problem is as follows:
Whenever I put a disc in and press either reset or controller input to retract the disc, it starts to go in, pauses for a split second along the way, continues in, and then spits it right back out.
However, if I put the tray by hand, just a little nudge as to make the drive retract automatically, the system will work just fine.

I have replaced both the belt and the motor/switches already, but that did not help.  Any pointers?  Thanks.

[kendrick]

If the tray is automatically coming back out again, that's an indicator that one of the gears is stuck, or that there's actually an obstruction. In rare cases, one of the rails might actually be bent or deformed. The Model 1 Sega CD unit is hard to diagnose for this problem, because you can't exactly have the cover off during normal operation to see where the tray stops, or why. See if you can't pop the emergency release inside with the cover off, and then try sliding the tray back and forth to see where it stops.

Of course, now I'm inspired to hack together a Megadrive expansion extension, so it would be possible to have a Genesis connected to an operating Sega CD unit with both units powered up.

[kcsims]

I'll give it a shot.
The wierd thing to me is that if I just tap the drive in, not even push it all the way by hand, just as to get it to auto-retact, works fine.

I have taken it apart several times to replace the belt and motor/switches and didn't see anything in the way.  Once when I put it back together, it was slightly off center with the gears and would get stuck, so I'm real careful for that now.  I'll give that a shot, but if anyone has any other advice, please let me know.  Thanks.

[kcsims]

I looked inside again, I do no see anything that would be obstructing the drive from going back in, like I said, it will go in all by itself if I give it that first little nudge.

Which gears would I be looking at to see if it is getting stuck?  Nothing appears physically with either the white or black gears controlling the tray.  Worst case, I just nudge it in, works everytime....just bothering me.


Thanks.

[kendrick]

This is a little bit past my experience at this point, but I'm guess that there's a calibration issue. If tapping the front of the tray gets it to retract, then that says to me that it's extended too far out of position and doesn't realize that it should be encountering resistance at that point. Nudging it puts it back into the spot where the drive goes "Oh, I should retract now."

All first-gen Sega CD units have Sony drives, right? I wonder idly if there's any calibration marks in there, where you line up the gears and the tray so that all the arrows match up. That would be a 'fresh from the factory'  configuration that the techs assembling the unit would start it off with. If I can find mine, I'll crack it open and see myself.

[kcsims]

When I say I push it back in, I mean in the same way that you can push any CD/DVD drive back in by hand instead of pressing the eject button.  There is no play in it, it is just the safety feature for drive trays.

[ken_cinder]

I just disassembled an LG PC drive that was doing this sort of thing, plus refusing to open 50% of the time.
What is most likely, is that there is some build up in the plastic toothed rails (Along the side of the actual plastic disc tray) and/or build up in the plastic sled rail for the lens assembly (This is the piece near the front, that slides back and forth and raises and lowers the lense assembly).

I ripped the entire unit apart, washed everything in the sink, blow dried it off and lubricated all the areas of movement. You'd think the drive was brand new now.

Given it's spitting the disc out, the mech is probably sensing resistance on that sled rail, and to keep the drive tray from smacking into the lens assembly (It goes down when the tray goes out) it's stopping the tray from going back in. Though obviously in your case, it's got one hell of a delayed reaction.