Model 1 Sega CD repair help

[Hobie-wan]

Look I'm not trying to argue with you, but you are mistaken on how tray CD drives work and misinformation isn't going to help anyone. This is what happens when you close a tray type CD drive.

1. A motor connected via a belt to a larger wheel turns. This larger wheel is connected to the tray and the spindle. Once the tray manages to fully retract, the spindle is cranked upwards and picks up the disc by the middle. A disk with a magnet above the spindle is attracted to the it once it gets close enough and the spindle, data disc, and upper disk are lifted up slightly and the clamping action of the magnet holds the disc firmly. There are switches that let it know that the tray closed fully and the spindle moved up into position.

2. Some very old drives had optical sensors to check if there was a disc in the way, like garage door openers or security gates at apartments notice there's a car in the way. However most just fire up the laser and see if there's a reflection from the disc. If you take a system like a Gamecube which uses a pop on spindle instead of a tray and fool it by pushing the 'lid closed' switch with the lip still open, you'll see the laser come on and the lens move up and down as it tries to focus on a reflection back from the disc.

3. If a disc is sensed, great. It tried to see if it can read the information on the disc, the TOC, and whatnot.

Now the reason for the belt that can slip is in case of jams. If the disc isn't sitting right and is a half inch too far forward and gets pinched, your cat thinks the player is evil and attacks the tray a sit closes, or your 2 year old has discovered buttons and is trying to feed the player, then it will detect a jam. If the tray doesn't hit the 'closed' switch within the usual amount of time or the spindle doesn't move into place within time, the drive assumes there's a jam and spits the tray back out.

In this case, the belt is slipping either because it is stretched from being old, there's a little dust making it slip, or another possibility we hadn't brought up is that the parts that slide for the spindle to come up need a little regreasing. Full stop. When the OP had the cover off and helped it just a little bit, the spindle came up and it read the disc that was in there just fine.

Tweaking the laser pot has absolutely nothing to do with the spindle moving into position properly. Unless it is discovered that it has trouble reading games after the tray and spindle are cooperating fully, the laser should not be adjusted at all. Having a loose belt or sticky gears has nothing at all to do with the laser. It will not cause the laser to fail because it never reaches the point where the laser comes on to see if there is a disc there.

[darkcat]

I've set up the steps of what to do the band is clearly going to be first. I don't see how your saying i don't know have a cd drive works when I've done around 100 rebuilds of CD/DVD/BR drives.
Anyways don't buy a new band, rubber isn't like most structure's its primary a polymer made of up chains of repeating units. These chains are chemically attached (cross linked), with this when rubber is stretched it will over time straighten out the chains. This can be reversed with heat (this is because of the chains moving more due to excitement from the heat.) Boiling water will work the best but just standard hot water out of the tap would be my first attempt. To get to the rubber band open the cd drive and then pull the power take apart the unit and remove the metal casing above the drive. Remove the two screws holding down the magnet for the Cd latch and then look towards the unit on the right hand side there's the band take it off with a small screw driver clean and soak in hot water (you could heat it with a lighter but then the band will become less moist thus more dense and will break easier) If it still won't play the disk then you're going to want to replace the laser or pot tweak it. I personally like to get the OP voltage to the laser then do the calcs to set the bjt at Q(Bjts never have a set Bdc value it will always be huge tolerances thus why we use pots to set the Q or near Q at the factory) if you want i can do the math to find that Ohm value if you end up having to do it.

anyways Hobie-wan every drive I've seen including the PS3 BR drive does use a sensor to see if there is a disk in the way its not always easy to see as it can be many types of sensors (infrared[ps3 uses this], Inductive, capacitive, mechanical and last magnetic ) Any drive that take a CD in needs to be programmed to look for something so it will turn the power to the lens think of it as a logic command theirs a clear set of operations.