Model 1 Sega Cd Audio problem

[vultar]

Hi all,

I've been looking around for info on this, but I haven't had any luck. Thanks in advance.

The system is a model 1 Sega CD that I got out of a Goodwill a few years ago. The only thing it did have with it was the metal plate that fits between the Genesis and the CD. The Genesis is an model 1 too. It worked fine when I got it.

When I got it out last (about 2 months ago) the audio in the game was skipping, so I cleaned it, and everything worked fine until a couple of days ago.

Now when I turn it on, there's a weird plusing/humming that happens on the splash screen as well as in the game. At first it sounded like feedback, but now it sounds more like the sound from the left or right channel is garbled. Spoken dialogue sounds tinny and scratchy. It also seems to happen in waves (ie. the background music will go on and then get replaced by the hum and then go back to music.) It's also definiately getting worse.

I switched the Genesis with my other one, and the problem's still there. Also the Genesis games don't have this problem.

I've opened it up, and it was pretty clean and I didn't see any obvious damage. I dusted it with some canned air, and cleaned up the contacts. Didn't help.

So, any idea what might be wrong with it, and how difficult it might be to fix it? I can solder a little, and am not afraid of opening these guys up (I've put a mod-chip and a region switch in a Saturn before), but I'm not an expert.

If the problem is beyond me, is the system somebody else would want for parts, or should I send it to the plastic graveyard?

Thanks again

[Squeept]

If your AC adapter is on the fritz, or is cheap knock-off crap, it can do some really horrible things to your audio. I don't think it would make it garbled, but it definitely would make it hum or pulse.

[raylydiard]

replace all caps.

[APE992]

Like raylydiard said, replacing all of the capacitors is probably going to fix it. I'd wager a good chunk of change on it. Bad caps are also known to cause noise and all sorts of fun problems for sound. On a NES of mine I recently recapped the audio output went from needing to have my stereo maxed out to about 10% of the amp's output levels because of bad caps.

I've done these before if you need someone to do it. While the soldering isn't too much more difficult than a Saturn region switch you have to be able to remove the caps AND properly clean the board if any electrolyte has leaked out. Very easy to damage the board just removing non-through hole caps if you aren't familiar with their removal, let alone cleaning the board.

[vultar]

Goodie...This is just a back up, so I'm not sure how far I want to go with it. How many caps are we talking about, and do you guys know about any online guides to do this? Also, do you think that this will only effect the audio, or is the rest of the system going to follow?

Thanks again guys, I appreciate the help.

[APE992]

Goodie...This is just a back up, so I'm not sure how far I want to go with it. How many caps are we talking about, and do you guys know about any online guides to do this? Also, do you think that this will only effect the audio, or is the rest of the system going to follow?

Thanks again guys, I appreciate the help.

Not sure how many honestly. Probably on the realm of 10-20 with a possibility of more. Never seen an online guide myself but it isn't difficult.

Keep it mind that SMD capacitors have a fun tendency to try to lift traces if you aren't good with their removal. It takes a bit of practice but it isn't a complicated procedure, just time consuming and very precise work. Enough that I'd suggest avoiding doing it yourself if you have doubts about your ability to not kill it. Model 1s aren't exactly a dime a dozen.

Capacitors are guaranteed to fail eventually but which ones fail first is dependent mostly on how well they were made to start with. SMD capacitors fail sooner than through hole capacitors, almost a guarentee. The rest of the capacitors in there are bound to fail sooner than later especially if the audio caps have already failed. Components like these are bought in large batches which would lead me to believe that the others probably have the same life span.

What I cannot say is how the failure of other capacitors will affect things. Maybe they will lose a bit of their spec values and still function. I'd wager a guess that eventually it'll refuse to read CDs or maybe just refuse to power on. I've got a Playstation here I strongly suspect won't power on for this reason (PSU is fine, fuses are fine, etc. Just won't boot up).

Just FYI I'm pretty cheap when it comes to recapping hardware. I order my parts in bulk for dirt cheap and consider restoration (as well as landfill prevention) top priority for these old guys.

If you really want to attempt this on your own here is a video detailing how its done for GameGears:
http://www.youtube.com/watch?v=noHzoVdimkQ

For example here is a Model 2 SegaCD board:


All of the capacitors I can see with this shot are through hole capacitors. Pretty easy to remove with the right tools but the board is fussy enough to give me problems on occasion. I'm pretty sure there are a few SMD capacitors somewhere but from what I can recall on the model 2 the relevant capacitors are up top towards the audio jacks.