Sega CD Model 2, fails when warm?

Sega CD Model 2, fails when warm? [SOLVED]

I pulled my genesis model 1 out of my back room after years of storage. Growing up I always wanted the cd drive... I indulged myself 20 years later and picked up a "working" model 2 drive off ebay.



I also scored a copy of Sonic CD to put the unit to good use. I pop the disc in and boom everything seems great. I'm playing sonic cd, memories of sega are coming back. I'm stoked. Around the 4th level, the background music stops playing, no biggie I think... I finish the level -> see my score -> screen goes black to load the next level but the next level never loads.

It hangs, I wait maybe 30 seconds. The access led is solid during this time. I pop the disc drive open and the disc isn't even spinning? So I turn the power off and turn it back on. It struggles to load the game. It will load the bios, act like its booting the game and then reset itself and goes back to the bios screen. I spent about 5-10 minds of turning off and on before it kicked into the game intro; but there was no background music. Just awkward silence with sonic looking at me. I hit start new game and what do you know black screen that hangs again.

Off the Internet to investigate. I didn't find much, to help in my situation. Mostly threads about not reading discs at all and blown fuses.

I give up for night and try the unit again the next day. Everything seems great again. I get farther through the game then the day before and hoped last night was just a fluke. But eventually the same thing happens and after multiple tests it always happens. It fails when the unit is warmed up which is about 10min.

I popped open the case to inspect it. All the caps look great, nothing is leaking. However I'd imagine that doesn't mean there all good. The laser is a sony kss-240a.

Any help would greatly be appreciated!

Thanks
Dan

 

I would be replacing caps as a first thing to do. Luckily it isn'a later jvc drive board, they have a lot of surface mount stuff on the under side of the board that gets in the way lol!

 

I had a Sega CD do this on Lunar The Silver Star, This seems to be a compatibility issue with many units based on the KSS-240a, when I asked about the issue with Lunar I was told that a few games did that including Sonic CD. The problem has to do with the handling of redbook audio looping, if it is the same problem it will happen randomly when it reaches the end of the music track and restarts the song. I don't think it is possible to fix. There are workarounds though.
1: when possible do not allow the the background music to loop, but this is impractical if you want to explore.
2: once it glitches gently slap the cd lid about 95% of the time the music will restart on the first try, DO NOT change areas until the music restarts or the game will crash.
3: the only long term solution is to get a different unit, I have never seen this happen on anything other than a 240 unit. Yet every 240 unit I have bothered to test does this with varying degrees of frequency.

 

I have a game cube which suffers from "thermo sensibility"
It works for like 3 min, then it hangs. Then it needs to cool down a bit to work for another 3 min later on.

 

I figured that would be my next step. Do the surface mount caps need replaced? There sure are quite a few of those. I also just took some pictures, do you see anything that jumps out. I understand its more than likely hard to see anything via pictures. I do see one transistor mounted to a heatsink with thermal paste... Have you heard of these overheating and causing problems? I

After you reset the game did the game disc read? After my unit is warm it wont even get past the bios, which wouldn't be related to audio tracks at this point? I perhaps should get a FMV game that doesn't use audio tracks and confirm the same thing happens.

 

Wow never seen this (my model 1 with the kss240 is packed away). I thought the model 2 had 3 lasers, sony kss210, samsung soh90 & the jvc opt 6? Does your laser have a single ribbon or 2 small looms?

 

My model two has the 240 with the single ribbon cable.

I decided to do some more testing this weekend. I grabbed a couple isos for testing purposes. I wanted to first try a full FMV game; nightrap fails after about 10 min. Message pops up saying: error while reading disc please wait. I tried tokimemofan suggestion of taping the top of the cd unit. I can hear the laser move and retry reading, but doesn't matter.

I will be getting some caps this week, so I'll let you know what happens after swapping them out.

 

One word for you:
Capacitors


So yes, have all electrolytic capacitors replaced.

 

Some updates on this.

I picked up some caps from a place called console 5. I started with the main board, no real issues replacing them. I reassembled the unit and popped in sonic cd. Pretty much no change. However it did do something slightly different. In the water level of the game, the music did stop playing. I finished the level and the game DID continue on to the next level and music started again. But it failed shortly after and I got stuck at a black screen. I took the unit apart again and started to replace the caps on the cd-rom module. This was a pain, I couldn't figure out how to get the spindle off the drive motor. I was afraid of cracking of plastic trying to push it off. But I some how made it work by spinning the laser around while I replaced the caps. I had high hopes of this working, but again something thing happened. It would still lock up after about 10mins from a cold start.

I started looking at the laser pots. Everywhere I read says don't mess with them. And if you do only mess with the laser power pot. I kinda thought to myself that the power pot was good, since it worked when cold. I found a random forum of a guy fixing a sony receiver with the kss-240a who had similar issues of mine. He ended up moving the focus pot to fix his problems. It was his conclusion that of the laser had slightly dropped over the course of the receivers age and need to be readjusted. He was using an oscilloscope to make adjustments. I don't have a scope but at this point what were my options? Get a new laser? So I figured I'd give it a go with the guess and check method.

I made the unit work with the cover off so I had easy access to the pots while it was running. I popped sonic cd back and went to the music player feature. I started the music and slightly turned the middle pot roughly 3-5 degrees counterclockwise wise. Now the waiting game started; after about 30 mins of playing music it was still going strong!!!!

I jumped into the game and no more issues!!!

 

Is you disc in good shape you may need a new laser replacement.

 

The game is in perfect shape. Burnt cds also worked well when the unit was cold. All cds seemed to fail when the unit was warm. But like I said adjusting the focus pot fixed the issue!

 

Interesting, I wonder if a similar fix would work on my gamecube.

 

Give it a try and let us know if it worked.

 

I never heard of Gamecube consoles with capacitor problems, so it's very likely that the issue will be the laser pickup itself.

 

Nice to hear the problem was solved. Enjoy it now

 

I was not referring to recapping, but to adjusting focus.
As I said earlier the game cube stops reading discs when warm.
But From what I read earlier it might need complete replacement of the pickup.

 

If you knew a little more about the technology you would understand what I meant. Anyway let me explain, then:

Laser diodes are extremely sensitive to temperature, so to compensate for that, the lasers on optical pickups are powered using an feedback system which makes sure the optical output is kept constant regardless of the temperature. The pot on the body of the laser pickup adjusts the reference for that feedback circuit.

The input for the feedback is a photodiode which exists on the same die (or sometimes just in the same encapsulation) providing a precise reference of how much light is being generated. One way laser diodes can fail is one which cause them to heat too much, which in turn causes it to generate less light under the same current it would require to generate enough light while cold. So once the maximum threshold the adjustment circuit is capable of is reached, the only thing that will happen is the light get dimmer.

So that's one of the common ways laser diodes fail. Putting some extra current on the laser diode (using the adjustment pot) could get you some extra useful life from the device but usually you won't get more than a few months of use.

 

Thanks for clarifying this mechanism of failure, admittedly I did not know that.

This still leaves me with a question, if the standard pot is to adjust the amount of current the diode gets, what about that second pot ( focus ) that the OP mention he used, which I have never heard about before?

 

As per old CD-Player technology (the hardware used on MEGA-CD is 2nd generation CD player technology) the chips used on the MEGA-CD were yet not capable of automatic adjusting, so there might be pots for focus bias, focus gain, tracking bias and tracking gain. If I remember it well, MEGA-CD had only the bias pots, as adjustment of gain could be omitted. So, these adjustments are needed to exist since each laser pickup had slightly different electrical and mechanical characteristics even when new.

Even modern stuff like the PS2 have such adjusts, but they're electronical, saved on the eeprom memory of the device.