Sega CD Model 1 Repair...

[mcnougat]

I have a Sega Genesis Model 1 connected to a Sega CD Model 1, and the Genesis part works fine.

The Sega CD loads up the bios and prompts for a new disk, and the disk tray opens and closes, but there is no spin-up. The access light blinks forever, sometimes it spits the CD out again.

Sometimes I hear a clicking noise as the tray opens or closes, or when it just closed.

I've already tried cleaning the lens with 71% isopropyl alcohol but that hasn't worked.

What next?

Edit: Thanks in advance.

[Tokimemofan]

I have a Sega Genesis Model 1 connected to a Sega CD Model 1, and the Genesis part works fine.

The Sega CD loads up the bios and prompts for a new disk, and the disk tray opens and closes, but there is no spin-up. The access light blinks forever, sometimes it spits the CD out again.

Sometimes I hear a clicking noise as the tray opens or closes, or when it just closed.

I've already tried cleaning the lens with 71% isopropyl alcohol but that hasn't worked.

What next?

Wrong section. The tray normally goes in and then the spindle assembly rises to catch the CD. make sure that it properly completes that process as these tend to jam between those steps.

[mcnougat]

How do I do that? Has anyone else done it and posted a tutorial?

[Tokimemofan]

How do I do that? Has anyone else done it and posted a tutorial?

It isn't the easiest to do. Open the sega CD case and remove the grounding plate over the drive then hook it up. Watch it eject and reload the tray. If the spindle and laser don't rise to a level position then the sensor switch never gets flipped and it gives up and ejects the tray. I need to fix mine today so I'll take some photos

Make sure after opening that this is the revision that. If not look at thishttp://www.racketboy.com/forum/viewtopic.php?f=17&t=8063
Note the spring in one photo, that was what jammed in mine. fix it as shown if it is misaligned
Note the belt, these degrade over time, check for damage. If it looks good remove it and rinse it with some soap, remove any grease on the pulleys. Re-grease the gears if needed
Note the grey clip. near the blue switch, it should move smoothly hitting the switch one way or the other as the straight gear raises the spindle.
DO NOT REINSTALL THE TRAY SCREW UNTIL YOU PUSH THE TRAY TO THE BACK. That is the easiest mistake you could make, and you will have a lot of trouble fixing it.

[mcnougat]

Are you asking me to make the drive open and close while the Sega CD is disassembled enough for me to see what's going on inside? I can only make the drive open and close when the Sega Genesis is sitting on top of the Sega CD, connected through the intended port there. How do I do what you are asking of me?

Edit: And what 'revision' are you talking about?

Edit 2: I have opened up the Sega CD and I have located the gear that makes the tray open and close, but it seems to work fine. Can you circle the important parts of the photos in your previous post, please?

[Tokimemofan]

Are you asking me to make the drive open and close while the Sega CD is disassembled enough for me to see what's going on inside? I can only make the drive open and close when the Sega Genesis is sitting on top of the Sega CD, connected through the intended port there. How do I do what you are asking of me?

Edit: And what 'revision' are you talking about?

Edit 2: I have opened up the Sega CD and I have located the gear that makes the tray open and close, but it seems to work fine. Can you circle the important parts of the photos in your previous post, please?

1: Yes you need to watch and listen to it eject. You may need a buddy to hold the Genesis in place. If you have a Genesis 2 or can borrow one it will be easier to use that than the model 1.

2: Some units are different. It appears that some use a large black timing gear, mine doesn't so I can't help if yours is like that, but that link above describes the issue on that version.

3: look at the 3rd photo noticing how the spindle is tilted and sunken, that is what a jammed unit looks like when closed, It should rise to lift the CD and catch the magnet clamp.

[xelement5x]

Wow, that an interesting version of the Model 1 you've got Tokimemofan. Almost every one I've ever taken apart uses that big black gear as a main part of the timing. Is it a US version or a MegaCD from somewhere else in the world?

[Tokimemofan]

Wow, that an interesting version of the Model 1 you've got Tokimemofan. Almost every one I've ever taken apart uses that big black gear as a main part of the timing. Is it a US version or a MegaCD from somewhere else in the world?

It is a NTSC-U/C version, date code September 1992.
Edit: I guess it was a launch unit, it was made a month before release day. Can't believe I never noticed even though I've had it for more than 5 years. BTW I've seen 3 versions of the model 2, never trust a teardown guide for these.

[Oldskool]

The common one seems to be the one with the big black gear. That's the one that I've always noticed anyways. It's really hard to make a walkthrough on these things, there are just too many different possibilities why it's not working, then the revisions, plus trying to explain it all in words.

[xelement5x]

Yeah, I totally agree with the troubleshooting aspect. I started working on a guide but abandoned it partway through after I got carpal tunnel

[mcnougat]

Well, I for one have not given up!

Just powered on the thing today with the top part of the case off. The assembly seems to swing up a bit when it closes. And there's still the clicking sometimes when it closes. Also, when it's about to open, the assembly swings down that bit before it opens.

Another small thing I've noticed is that one of the gears looks like it's missing a tooth. It's the big black gear that opens and closes the drive. I'll get a picture in a sec. Is the "missing tooth" part of the design, or could it be a piece that broke?

Edit: Sorry for the cell phone-quality photo.

Edit 2: The clicking is more like a zipping ... "ZZZIIIIIIIIIIIP!"

[Tokimemofan]

Seems like you have the common version, I got the rare. The missing tooth seems to be the problem, I'd part it out and buy a new one if you don't have the part available.
See these.
http://www.eidolons-inn.net/tiki-vie...cdm8fk370k3f07
http://www.cheapassgamer.com/forums/...47#post4908847
http://www.youtube.com/watch?v=ddGTV6y8MOg&NR=1

[raylydiard]

Hi guys i have a ton of sega spares could you take a snap shot of what part you need and just pm me.

[Tokimemofan]

Hi guys i have a ton of sega spares could you take a snap shot of what part you need and just pm me.

Mine is fine now, I just put a spring in wrong last time I gave it a tune-up. If anyone ever needs assembly photos of this version please PM me with your request.

[mcnougat]

When I place a disc in manually (while the system is taken apart), it will spin up for a second or two, then the ZZZZIIIIIPPPPing, then nothing. And with subsequent ejecting/closing of the tray, there is no spin-up. Do I need to take the whole CD assembly out and disassemble it further to find a piece that's missing? If so, anyone know a good general guide to taking apart a CD assembly? I have never taken apart something so complicated.

[Tokimemofan]

Never encountered a problem like that. sorry.

[xelement5x]

What I do when the system is apart is manually raise the cd mech and lock it, then put the disc on and the top magnetic part and see if the system will boot up and the game will play. This way I know the laser is still fully functional before proceeding to repair the crazy mechanical parts.

[Tokimemofan]

Actually I think I might know what is broken, but you probably won't like it. Under the spindle hub that holds the disc there is a switch that detects when the laser has been pulled all the way in, analogous to the track 0 detect in a floppy drive. If that switch is either shorted or open, the laser can't look for the lead in on the CD. Most CD mechs don't have a fallback for that and the Sega CD Model 1 behaves especially badly, even spinning the CD backwards at one point during a 20 second freakout that ended with the drive ejecting. This is probably the most catastrophic mech failure that can happen short of the CD shattering. I would sell it as is, get a ram cart and grab your saves and leave it to someone who needs parts. BTW to confirm this, check to see which gears are grinding, if it is the set that moves the laser then, it is probably the switch.

[Oldskool]

They all look like they have a broken tooth. That's normal.

[Oldskool]

What I do when the system is apart is manually raise the cd mech and lock it, then put the disc on and the top magnetic part and see if the system will boot up and the game will play. This way I know the laser is still fully functional before proceeding to repair the crazy mechanical parts.

Yup, what you said. Also take a look at the limit switches and make sure they are in the proper positions after you manually set the disc before you turn on the console.

I always recommend a new belt too. It can cause all sorts of odd things to happen, the most common one is that it will eject the cd as soon as you put it in. Just because the belt looks ok doesn't mean that it is. They get stretched and have a difficult time raising up the laser assembly. Although, technically if you manually set the disc/laser assembly into the proper position you are basically doing the work of the belt. So for testing purposes it's not needed much.

Another thing - people worry too much about the aligning of the gears. They are engineered so that if they are out of place they somehow always end up back in the same position. I noticed this after trying to adjust gears for hours and hours, they always seemed to reset back to a default position. I think this is an engineered fail safe so that if the gear ever slips the console can set their positions. It achieves this when the laser assembly has been fully raised the gear will keep turning until it hits the stop on it. Of course if you have a worn belt it will not raise the laser assembly all the way up which will make you think it's the gears. Rather than wasting time with the gears (that are rarely ever actually broken) focus on the belt, the laser assembly hinges and the limit switches.

Again, it's very difficult to figure out through a forum. The part that confuses people the most I think is the tray and the gears. You just have to turn every thing and see what does what. Once you gain an understanding of how it all works you will figure out the problem. And because everyone is always talking about the gears, don't let that fool you into straying from other more simpler issues.