Reading Discs

[Paspie]

Hi there, I've had my Dreamcast for more than three years but as you can tell from the title, I have a pretty old issue with it. To put it plainly, there are some games in my collection that it will refuse to load at all (or not get past the white Sega Enterprises screen), some of them will load after much deliberation but the laser assembly seems to give up after extended play. Meanwhile, some of them load absolutely fine with no skipping at all. I tend to have the most luck with Audio CDs and CD-Rs, while the larger GD-ROM games can be a little less reliable.

I have looked at a few solutions over the years, one was to open the case and twist a knob on the side of the laser assembly which supposedly alters the speed of the motor, this didn't change the success rate with loading games and in the end I actually broke it slightly be using a bit too much force.

I am skeptical over the replacement Dreamcast laser assembly's, since there may only be a CD laser on it, not a GD-ROM one. They are also quite expensive, especially as I'd have to buy it overseas (I'm in the UK).

Another option I have recently been looking into replacing or even lubricating the motor. I have not seen many threads on this but considering that my motor is practically giving on spinning the disc, rather than the laser, there may be a chance that that needs to be looking at instead. The problem is, I don't have much experience with this kind of work.....

....which is why I've come to you guys. Does anyone else here have pointers on getting Dreamcast to load discs without any hiccups at all? It is a rather common issue and I should have figured it out by now from all the documentation elsewhere on the internet, but I unfortunately obviously haven't. I wouldn't like to have to keep buying more Dreamcasts to find one that works for me, I don't want to put the working technology in my unit to waste. So thanks for reading and feel free to put your comments down below.

[elmagicochrisg]

Never ever pot tweak a laser without using a multimeter.

There's two little contact points next to the pot screw. Those are the points you need to measure the laser's resistance. Measure the initial resistance so you can always return to that value. Turning the pot to the right will lower resistance, which in most cases is what you need. Only make small adjustments of 10 - 20 Ohm at a time and retest the laser after every adjustment. This can be a very time consuming process because you have to assemble and disassemble the laser every time you have to test it. Be careful not to break the lense's ribbon cable while doing all this. Ribbon cables are quite fragile. Also keep in mind turning the pot too much to the right will lower resistance too much and burn the lens. Once you burn the lens, there's no turning back...

From personal experience I know when the disc stops spinning -lense's motor shuts down as if it has no force to keep the disc spinning- the resistance is too high. When it starts spinning like crazy resistance is too low. Once it starts spinning like crazy, don't turn the pot to the right any more unless you want to burn the laser...

Other things you could do...

- Clean the lens with pure (+90 percent) alcohol.
- Grease the lense's pole with silicone grease.

[cOcOoO]

Never ever pot tweak a laser without using a multimeter.

Been calibrating lenses without a multimeter for years, not a single problem. You just need to be careful. Obviously, if you have one, you will be better off using it.

There's two little contact points next to the pot screw.

Wrong: there's 3.

Those are the points you need to measure the laser's resistance. Measure the initial resistance so you can always return to that value. Turning the pot to the right will lower resistance, which in most cases is what you need. Only make small adjustments of 10 - 20 Ohm at a time and retest the laser after every adjustment.

While this is true, it's pretty hard to increase resistance by 10Ω, specially if you are new to this kind of thing.

This can be a very time consuming process because you have to assemble and disassemble the laser every time you have to test it.

Not true. Just flip the laser assembly so it will be upside down LIKE THIS and tweak the pot just like that. Remember to free up the red, black and white cables from the plastic tabs BEFORE doing this. For testing, put the assembly back at it's original position, put a disc, and turn the console on while holding the tiny black plastic lever in the upper right corner of the assembly back (this is the "closed lid" switch).

Be careful not to break the lense's ribbon cable while doing all this. Ribbon cables are quite fragile.

This x9999.

Also keep in mind turning the pot too much to the right will lower resistance too much and burn the lens. Once you burn the lens, there's no turning back...

This MIGHT be true, but it never happened to me, EVER. If the disc starts spinning back and forth, you've lowered the resistance too much. Go back a little.

- Clean the lens with pure (+90 percent) alcohol.

NEVER do this. Rubbing alcohol leaves residue, it oxydizes and it doesn't dry correctly. Isopropyl alcohol was invented for a reason.

- Grease the lense's pole with silicone grease.

Machine oil works quite well, too.

[Paspie]

Starting to like the idea of greasing the pole, maybe the laser unit isn't able to move fast enough to read some discs properly, which is why it gives up so often. I'll get on that soon hopefully, but in the meantime, I'm slightly worried about even its current functionality thanks to slight errors in the ways I've handled the console while disassembling and so forth (particularly of note the laser). Thanks to Rez, the upcoming Redux game, and many other games for Sega and non-Sega systems, my interest in video gaming has had a bit of a reboot and getting a fully functional Dreamcast would be really beneficial at this time.

[Raen]

Also keep in mind turning the pot too much to the right will lower resistance too much and burn the lens. Once you burn the lens, there's no turning back...

This MIGHT be true, but it never happened to me, EVER.

I subscribe this. I've turned the potentiometer all the way around, be it to the right or to the left, and never burned the lens. The potentiometer seems to work like a loose screw because it can turn all the way around indefinitely, and for which 360º turn it goes back to the value it had.

I think that there's no problem turning the potentiometer beyond the working zone, the laser assembly chip must have some kind of voltage detector and so it protects the rest of laser circuit. The motor will spin the disc too fast, too slow or back and forth but the laser simply won't be able to read and depending on the situation, it will give up reading the disc sooner or later.

Greasing the pole is OK, I've done this on my first Dreamcast that I bought back in the day as it from time to time struggles to read discs (specially the games with CDDA, where music hiccups occur), because one day it fell from the table.
I use an universal silicon oil spray (for use on door hinges, etc) and it solves the problem, the optical drive loads the data as fast as it should because the laser assembly moves faster again and also quieter.

[Paspie]

It seems during storage my Dreamcast developed another problem: resetting randomly soon after startup. I rectified this by WD40ing the contact pins on the PSU, but the thing is still refusing to read my most unreliable game: Chu Chu Rocket. I have greased both visable poles on the underside of the laser unit to no avail, but it does sound slightly quieter. Its kinda weird 'cause the same disc will play just fine as an audio CD on the Dreamcast itself, but it won't boot up past the Sega Enterprices Licence screen. Is there anything at a motherboard level that would be causing a reject of certain games but not others? I don't see what a motor could do to make this happen.

[Paspie]

I decided to give it one last shot by lubricating the motor with WD40. This is probably now the most ambitious repair project I have ever performed, and frankly that kindof showed when I was piecing it back together. There is a metal plate under the spindle that attached to the motor, but I couldn't get the two items to make contact after I have WD40ed the motor. As a result, I can't get the damn thing to spin a disc. I am also concerned about the white ribbon cable, it is an absolute *** to plug back into the optical assembly because there is almost no space for a decent pair of pliers to do the work without the bodging the integrity of the cable.

In short, I've made a kind of usable Dreamcast into a completely dead one. Not to worry though, because its not broken as such, just my skills haven't allowed for a successful process. I'll give it a rest for now, but tomorrow I'll see if I can get the motor closer to the metal plate so that there is a faint chance of spinning the disc and playing some awesome video games.

[Raen]

Its kinda weird 'cause the same disc will play just fine as an audio CD on the Dreamcast itself, but it won't boot up past the Sega Enterprices Licence screen.

From my experience, that is related to the laser, you may have to recalibrate it (better).

As to the ribbon cable, you disconnected it? I think that you don't need to, unless I'm not seeing what you're doing exactly.

There are numerous tutorials that show that you can get access to the laser assembly without disconnecting the ribbon cable, here's one that Adam made:

[youtube]http://www.youtube.com/watch?v=6cKsWwi7qIE[/youtube]

[Paspie]

I disconnected the ribbon cable so that it would be easier to work with. I tried the calibration thing a while ago and it never seemed to make much of a difference.

[Raen]

Hmm, ok, but now you will have a hard time connecting it back as you have seen.