DC is scratching all of my discs

[futurer0ckstar]

My Dreamcast is scratching my GD-ROMs and my music CD-Rs.

I took apart the console, and I turned it on while pushing the door trigger (without a disc), and it seems that the laser bobs up and down a couple of times each time I push the trigger. After I tried that, I put a disc in and pushed the trigger, while carefully watching the space between the disc and the drive. I couldn't see the laser hitting the disc. Yet, it always ends up scratching my games.

Also, the scratches usually have a pattern like this:

_______________________________
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

Or in words, a long horizontal scratch that runs under, over, or through a large group of short vertical scratches.

[K_I_R_E_E_K]

Are you sure nothing is touching the disk?
Are you sure the disks are not already scratched? (from the box where you keep them for example)
Do you listen to any noise while playing?

[futurer0ckstar]

(a) I don't really know. But, I did take one of those clear discs you get from DVD-R packages and see if the laser was actually hitting it when it was moving. It was getting extremely close, that's for sure, but I'm not sure if it was actually hitting the disc.

(b) 100% sure. I got a copy of MDK2 brand new and I noticed that every time I took it out after playing, there was a new scratch somewhere. Same thing with Tony Hawk's Pro Skater 1 and 2, and I bought those brand new as well. MDK2 no longer plays, and I'm afraid that Tony Hawk is getting close.

(c) It's making this loud grinding noise every time it reads from a disc, but I did some research and everybody's saying that it's just the drive working and that it's perfectly normal. Also, there's a very quiet ringing noise coming from the console every now and then. Other than that, I haven't noticed anything.

[K_I_R_E_E_K]

Can't post a picture right now.

By placing a cd just on the drive i notice a 1mm distance between the cd and the drive itself.
by placing the top white plastic i noticed that everthing will be at a lower level then the drive, so i guess a 1,1mm or 1,2mm is the biggest distance, there is no way the cd touches the drive or any other part of the dc.

The white plastic (top cover) however, has 2 black and soft areas, in your dc, is there any contact between these and the cd? since this is hard to see, i'll ask this in another way, check the distance between the cd and the drive, now regarding these 2 soft black areas, are they tall enough to touch the cd? is there any dirt on these parts capable of making a scratch?

[futurer0ckstar]

From what I can see, those soft areas may or may not be (but probably aren't) touching the discs. They aren't dirty, either.

Also, this slipped my mind earlier, but the scratches seem very random in where they're located on the discs. There's no particular location where it keeps happening, and you'd think that that would be the case if the soft areas were scratching the discs. So I'm pretty sure the laser is actually scratching the discs. But it's so weird, I mean, if the laser was scratching them, wouldn't I see some damage on the laser, too? Yet it looks perfectly fine.

I've been listening a bit closer to the noises coming from the console, and I'm noticing that sometimes, when I'm at a loading screen, it starts making a ringing noise. The loading finishes, the noise keeps going, and then when I get to another loading screen, it stops. And then it can start again at any loading screen.

I tried watching the gap during a loading screen, but even if the laser actually was hitting the disc, I wasn't able to see anything.

If the laser is actually hitting the discs, what kind of noise do you think it would be making? It might be helpful to have some sort of idea as to what kind of noise it would make so I can listen for it next time I start it up.

[r34per]

ive niticed a few scratches on mai burned dc games. might just be mai cd case doing it tho. :/

[Dingo]

I wouldn't actually expect you to see any damage to the lens even if it is scratching the discs. It's made of glass. Only think I know that cuts glass is a diamond, and I don't think your GD-Roms are made from that.

I can't imagine what else could be scratching them, so I think it's safe to assume it's the laser lens doing it. It's the only part in the drive that is capable of moving to 'random locations' like you describe as well as the only part of the drive that is actuated vertically to obtain focus.

I'd wager dollars to doughnuts that it is the laser doing the scratching.
Has your DC always done this, or did it just start doing it for 'no reason'? Did you make any mechanical or electrical adjustments to the DC before this started happening? Have you made any mods to this DC, or messed with the pot on the backside of the laser unit at all? Have you ever dropped the DC in question from a significant height?


DC drives can be loud... in fact each of my DC's has a different sound to it's drive. I could wear a blindfold and tell you which one you turned on, but I wouldn't describe any of them (that were presently functional) as making a 'grinding' noise.

[futurer0ckstar]

@Dingo: Oh, okay. I'm glad my lens is fine, then.

I got my DC used about six years ago. It's been scratching discs ever since I got it (don't ask why I never checked the forums earlier--I don't know). I have never made any adjustments, and I checked the pot about a week ago and it was in its default position (unless someone made one full turn before I got it, in which case I think my DC would be dead by now). I have never dropped the DC.

Well, "grinding" is the only word I can think of to describe the noise, but even that doesn't sound right. Anyway, I checked some videos on YouTube where other people's DCs were making the exact same noise, and all the comments said it was a normal thing and that it was just the disc drive's motor working.

[futurer0ckstar]

This is a recording of the noises my DC makes. It's not good quality, but it's the best I could do. Note that the extremely high-pitched ringing noise (as well as a certain extremely low-pitched buzzing noise) is NOT my Dreamcast--that's just my mic being stupid. Everything else except for the ambience is my Dreamcast. Also, this "grinding noise" I keep referring to is loud, abrupt, and intermittent.

[Dingo]

Yeah, you are right... That sounds completely normal. That's the laser pickup moving back and forth finding a location on the disc. That sound would have nothing to do with the disc being scratched.


I'm still betting it's the lens doing the scratching. I don't know what kind of noise the lens hitting the disc would make either. You may not even hear it because the DC is just so loud in general.

The lens itself inside the laser-pickup is actuated in a few directions by some electro-magnets so that it can track and focus on the information. I could imagine that some damage to the stops in the mechanism could make the lens move high enough to scratch the disc if it's trying to focus on a particular section that might be a bit hard to read already.

It would be interesting to see if replacing the laser pickup would fix the problem. My guess is it would. But I doubt you have a spare lying around to do that with...


Something easy you could do to at least attempt to limit the problem would be to make sure your lens is clean. Use as high percentage isotropy alcohol as you can get and make sure there is no additives other than water in it. Also keep your discs clean (soap and water is fine). This won't fix the problem if it's being caused by what I just mentioned, but it could limit damage as the laser will have an easier time reading a disc and not need to do the extreme focusing that could cause it to hit the disc if one of the stops int he pickup is indeed damaged. I still wouldn't go putting any 'important' disc in it though. Arcing scratches that run parallel to the tracks on a CD are the worst kind .