Sega CD (M2) only reading certain discs.

[Opa Opa]

My model 2 Sega CD has been acting up recently. I can get Android Assault and Corpse Killer to load first time with no issues. However, whenever I put in Heart of the Alien I either get graphical issues or the game freezes. And the SCD will not recognize Lunar: The Silver Star at all.

When I put in Lunar it tries to read the disc and then it says "press start". I do and then it sends me to the disc menu. Then in the disc menu it says that there is "No Disc"...

I really don't know what the problem is. Lunar's surface looks flawless. Is it the laser eye that needs cleaning?

And if it does need cleaning will the methods mentioned in this thread work?
http://www.racketboy.com/forum/viewtopi ... 10&start=0
I know this thread is almost identical to the link above but I really don't know why the SCD will load certain games and not others...

Thanks everyone.

edit: & all these discs are legit. No burns. I haven't tried burned games on this unit yet.

edit 2: Plays non-burned music discs just fine. Switched out the Model 2 Genesis with a Model 1 and didn't affect anything. I heard something rattling when I picked up the SCD. Going to open it up tomorrow and see what's what.

[Opa Opa]

Okay... The rattling sound was made by a small piece of plastic broken off stirring around on the inside when moved. I don't think it had any affect on the actual system though.

I'll edit this with pics and more questions soon.
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edit 1:
Didn't see anything else wrong with it. Going to clean the laser's eye/lens/thing tomorrow.
Tested Lunar on Kega Fusion. Loaded it from my disc drive and it worked perfectly so it has to be the Sega CD.

Could the lens need replacing?
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edit 2: Okay...
Cleaned the lens. It seems that it loads the fmv games a little faster. Still no Lunar.

I'll try a burned disc soon.

[OmegaMaximum]

You could try reconnecting the Genesis to the SCD. The connection can get loose, especially if you don't have the mounting plate on the bottom of the Genesis. If that still doesn't work, I would maybe clean the male connector on the Genesis with a q-tip and a little rubbing alcohol. Other then that if the lens is clean and the game boots in emulation, you might want to consider changing the fuse that always goes, or just replace the unit.

[Opa Opa]

You could try reconnecting the Genesis to the SCD. The connection can get loose, especially if you don't have the mounting plate on the bottom of the Genesis. If that still doesn't work, I would maybe clean the male connector on the Genesis with a q-tip and a little rubbing alcohol. Other then that if the lens is clean and the game boots in emulation, you might want to consider changing the fuse that always goes, or just replace the unit.

Yeah the fuse seems fine. I'm planning on getting multiple hardware variations of the scd anyway so it isn't a big deal. I'll try cleaning the connectors.

[lordofduct]

I would stick to looking at the laser/read head assembly. I'd make sure that the plastic bit didn't get broken off from this part (for instance part of the head that moves the lens back and forth), this might slow down or otherwise throw off the read speed of the SCD.

Note the Sega-CD is a single speed CD-ROM, this leaves little room for error when it is reading disks. It also treats different types of data differently...

first - a cd-rom performs error checking after each sector of data. Each sector has a small chunk of data at the end to use to do this. If it fails to validate it can choose to re-read the data again.

The sega-cd may choose to re-read data at different times.

CDA - music in standard red-book audio format - if error occurs it just plays back the data as read. Being a single speed cd-rom it has no ability to buffer the audio. So instead of pausing audio playback it will instead play the sector as read... usually resulting in a clicking or fuzzy noise

FMV - can be buffered in memory, but due to enormous size of video in relation to small size of available memory results in very minimal buffer space. Error correction is minimal and if found will usually be dropped. This tends to result in dropped frames, skipping in the video.

Data - the important stuff, there is no way to 'ignore' sectors of normal game data. Either it's there or it's not. So when error checking it will repeatedly try to resolve errors until it gets it right... if duration is to long it commits a read error and fails out.



Due to this and the games you've had work, I'm leaning toward an inability to read disks... and thusly pay attention to possibly dirty lens OR worn out gears to move the lens head OR something blocking or damaging the lens head blocking it from moving properly.

Why?

Android Assault - this game is tiny as all hell. Remove the audio tracks and this thing can fit on a floppy drive.

Corpse Killer - ignoring the FMV (which is liberal in its error correction) the game is actually very small as well and located towards the beginning of the disk (inner loops are easier to read then outer loops).

Heart of the alien - The original "Out of this World" game is damn small, it's pretty small for a genesis game. But the sequel game and all the opening menus are graphics heavy because they weren't done using the same vector graphics that the original was done in. This means its getting larger, higher chance in data error, its passing somehow with graphical glitches.

Lunar Silver Star - the game is HUGE on disk. Not just the video, but the game itself with huge chunks of textual data, graphics data, and everything. It's an RPG... and the data is scattered all over the disk. You've pretty chosen a game that almost guarantees you uncovering any technical flaws with your SCD (Lunar 2 Eternal Blue being even better at it).


Furthermore you said after doing a first clean of the lens that the FMV games started playing more smoothly... lays in line with the theory.

Try greasing the lens head track, clean down the lens some more, and keep your fingers crossed.

[Niode]

Always nice to see you post on the forum LoD. Great information and couldn't agree more.

[Opa Opa]

Wow! Thanks lordofduct!
I cleaned the lens again but to no avail...Lunar still refuses to play...

A couple of questions...
Is the metal bar that the lens is being supported on (see pic) what you are saying needs to be greased?

And what kind of grease do I use on this? There are different kinds and I'm absolutely certain what I have isn't the proper thing to use.

edit: and sorry about the image quality. having to use a phone.

edit 2: almost forgot. That plastic piece that broke off was only part of the unit's inside molding. Nothing serious.

[lordofduct]

yes that track is your biggest concern right now.

As you can see by looking at it there is a pile of gears that handle the speed (think of it as a single speed transmission that ramps the velocity of the lens as you progress across the disk from inner to outer, or vice versa).

You should be cleaning off those gears as much as possible making sure they spin nice and clean, you can even add some silicone lubricant to the gears, only a little... I wouldn't be surprised if you find some white crusty silicone lubricant on it from the past.

As for the rod, you need a light liquid lubricant. And again barely any at all. I don't remember what it is, but I always just used the lubricant I used on my old model trains. It's like the consistency of wd-40.


Now of course these parts are supposed to function well enough with out regular lubrication (and todays actually are designed to not be lubricated at all). But your SegaCD is now 18 years old, and it's going to need some babying in this department if it was treated poorly through out its life.

[Opa Opa]

As for the rod, you need a light liquid lubricant. And again barely any at all. I don't remember what it is, but I always just used the lubricant I used on my old model trains. It's like the consistency of wd-40.

Do you think a little wd-40 applied with a q-tip would work? I know I have a can of it or should I just wait and get some kind of all-purpose lubricant at a hardware store?

(Although, I don't know if using wd-40 would have some ill effects on the plastic...)

[lordofduct]

I would be weary of WD-40, it likes to eat some plastics. I couldn't tell you for sure, but I'd say no.