Sega CD Model 1 sound issue

[Neurosis138]

So I picked up a Sega CD model 1 yesterday and it had an audio problem I could use some help solving.

Problem 1:
The disc drive would not read game discs, but would read music discs.  I was able to fix this by opening up the unit and making minor adjustments to the pots on the back of the cd assembly. 

Problem 2:
When the machine is first turned on, the audio will sound just fine.  After about two minutes of play, the cd game audio will have a sort of fuzzy sound in the background, which will gradually worsen the longer you play.  It sounds like the sound a record player would emit from a dirty or scratched record.  I also tested a music cd, and it will exhibit the same behavior, fine for the first couple minutes when the machine has been sitting, but a fuzz tone will start to develop after a couple minutes of use.

I recorded ths short video to show the audio issue.  It's hard to hear, but it's there if you listen closely:



This only happens from the cd audio, so I'm assuming it's a lens issue.  It also had the same sound issue prior to adjusting the pots, so it wasn't caused by that.  If anyone has any experience with this please let me know.  Also, does anyone know of a guide online that shows how to replace a lens on a sega cd model 1?

[bust3dstr8]

The problem is most likely the electrolitic caps in the CD sound section. You should just recap the whole unit and then test it again.

[Neurosis138]

The problem is most likely the electrolitic caps in the CD sound section. You should just recap the whole unit and then test it again.

Thanks for the reply.  Is there a tutorial somewhere on how to do this on a model 1?  I've never replaced caps before, but I suppose this would be a good unit to learn on.

[Samurai Ghost]

Yeah this sounds a lot like a capacitor problem. The same exact thing happens to DUOs after a while, as the caps can't hold the charge for a long time so the music degrades after some play or just doesn't play at all.

ApolloBoy might be able to help you as he works on a variety of systems. It might be difficult to replace the caps yourself if you've never done any work on electronics before.