Sega CD systems repair thread

[Madness Hero]

Howdy all, I recently aquired a model 1 CD. I finally got all my cords propper and everything seems to be working great except the disc drive. When powered up and opened regardless of if u put a disc in when you hit close it starts to close stalls slightly and then closes and then immediatley opens. Then if i power the system off and then back on the tray closes and stays shut until I press the button and thus repeats the cycle. Now I've come to understand changing the belt is usually the go to fix but I'm curious if it could be something else since it stays closed after the power on and off. Hoping an O.G. can get on here n give me the down low.

Edit: I forgot to mention this is a JVC drive, after doing a lil digging I noticed my disc tray is missing the gold screw at the back right hand corner of the disc tray is this screw intended to engage the gear sooner? And can some one take a picture of the screw or tell me if it's necessary and if it's the same size as the RF shield screws or larger?

[TrekkiesUnite118]

You may want to try setting the soldering iron at 300 to 315 degrees Celsius. I found that To work really well in soldering. If the solder pads only lifted and didn't tare you could remove the capacitors and get some high heat epoxy and reglue them down. As long as you can find the IC to replace it should be salvageable.

Some of the pads I wasn't able to salvage, but the trace is easy enough to see where it goes so making a patch is doable. The problem is at this point with the IC and all is that it's way beyond my skill level.

[Firebrandx]

Hoping experts on M1 Sega CD drives (USA) can shed some light on this, but I found I have to lift the front of the M1 SCD up about 25 degrees from level in order to prevent PCM audio/video skipping. Even CDDA was getting hit a little bit, but PCM was skipping like crazy. Tilting the console 25 degrees from the front removes ALL skipping. Ive already done a recap and replaced the drive belt. I'm thinking this is some sort of issue with the laser. I looked at the drive spindle and nothing appears to be wrong there that I can tell. Everything else on it works like a champ.

[Kamon]

Hey fellas my Mega Cd is on the fritz, fantastic thread BTW I've already learned a lot. I have a Model 1 Mega CD that is having issues with Audio after working fine for many years. Unlike the usual issue with Cd audio that im seeing in here frequently it's only the pcm audio thats been glitching out. Audio is crystal clear with cd playback but the bios screen music or travelling to the past in sonic cd has channels sound very choppy or missing entirely. I'm in the process of cleaning the boards and leaky caps but before I go crazy recapping everything which board should I be focusing on? Seems like the thin one at the back handles audio from what I'm seeing. Also can't find the roland pcm chip so if anyone knows where I should be looking point me in the right direction!

[kraftwerks]

Hello all.

I got a Model 2 that powered on but didn't read discs. I ordered a laser from Liberty and installed it today. Turn it on, it works! I let Tomcat Alley run in demo mode for a bit while I cleaned up my work area. After maybe 15 minutes I noticed that TA was skipping. I turned the system off and back on, and now it's not recognizing discs again. I don't imagine a laser would die that quickly, so maybe caps? I'll take it apart and give it a look over.

[crazyteknohed]

My Mega CD loses all its internal saves requiring a re-format when I haven’t played it. What can I do?

[Kamon]

I'm at a loss! Recapped both the main board and audio board and the PCM audio is still glitchy. I've also tried reflowing a majority of the ics with new flux and a bit of extra solder (just pulled across the pins didn't pull it out of circuit or anything) and still no luck. I'm starting to think I have a failed IC. Given what I've been reading it's the most unlikely cause but I don't know what else to look for. Problems is there's about 5 different chips associated with PCM audio that people have pointed to as culprits. I have service manuals so I know which to be checking at the least. Not exactly skilled with a multi meter beyond basic continuity testing, so any guidance on how to diagnose the ICs would be appreciated. HELP!

[Raijin Z]

The only idea I have is just a last-ditch solution, and that's to replace each of the suspected-bad ICs, testing after each as been replaced, and that's if you can even source replacements that aren't from a flooded basement.

[Blades]

I'm at a loss! Recapped both the main board and audio board and the PCM audio is still glitchy. I've also tried reflowing a majority of the ics with new flux and a bit of extra solder (just pulled across the pins didn't pull it out of circuit or anything) and still no luck. I'm starting to think I have a failed IC. Given what I've been reading it's the most unlikely cause but I don't know what else to look for. Problems is there's about 5 different chips associated with PCM audio that people have pointed to as culprits. I have service manuals so I know which to be checking at the least. Not exactly skilled with a multi meter beyond basic continuity testing, so any guidance on how to diagnose the ICs would be appreciated. HELP!

Have you tested the RAM?

[Kamon]

Have you tested the RAM?

Nothing more than using diode check to see how much voltage goes through each pin. Ic 14 and ic 15 don't have any values out of the ordinary. A psuedo ram chip (ic 10) has one pin that reads waaay out compared to its twin but from what I understand those two chips aren't associated with the audio at all. I'm told I should check the voltage input while the unit is powered but don't know how to go about that. After all the unit doesn't leave standby until it's got a megadrive attached with covers the top completely.

[Elrinth]

I just bought a Sega CD model 1 from a guy who claimed it was working. It got stuck when going out of the tray cuz the lazer wouldn't go up and down. Now I have fixed so it goes up and down after 2 nights work. But it still won't spin up the cd. It makes some weird noise when it's "in", then after awhile it opens the tray again. Does the laser need height adjustment? If so, which of the 3 pots on the laser is height adjustment?

[majinga]

Check the close switch

[Chaos Fusion]

Just earlier today, my Jap Model 1 SS was failing to play audio while I was playing Daytona and suddenly crashed to the CD Player.
Anyone else had this issue?
Started occuring randomly today so I'm leaning towards it being the disc drive being the culprit as the system will play fine, one time I started a race and it hung at the load screen, load light not displaying.
The new Power Supply definitely outputs the correct voltages.
Don't think it's the capacitors as the systems looks and sounds fine though will need to crack it open to examine the caps.

[SPiET]

Hi everybody,

I'm fairly new here but i just acquired a SEGA MEGA CD Jap Model 1, without any cables or ac adapter. The guy didn't knew if it was working or not. Well it isn't Not powering on.

So i opened the case and tested all the fuses (especially F1) and still have voltage on it.

Attachment 15188

Now when taking out the sub board (see above) i noticed that the ribbon cable as screwed. I'm not sure if this was already like that or not but i guess that might be reason why it isn't powering on at all.

Attachment 15189

If i'm not mistaken this is a 21 pin flex cable (can anybody confirm this?) and i found this recently on aliexpress ( https://nl.aliexpress.com/item/32765...2e264c4dy4EHuc ). Should be the right one.

However while i'm waiting to get this cable (it still needs shipment from China) I tear apart the cd drive for cleaning and i accidentely forced the black little wheel that makes the cd drive up & down. It doesnt sit in place anymore so when opening the drive manually , the cd drive doesn't go up and down. Anybody know how to align this little black wheel , do i need to turn it again clockwise or ??

Thanks!

[majinga]

...
If i'm not mistaken this is a 21 pin flex cable (can anybody confirm this?) and i found this recently on aliexpress ( https://nl.aliexpress.com/item/32765...2e264c4dy4EHuc ). Should be the right one.
...

It's the wrong one. The right one have 1.25mm pitch. It's not easy to find as replacement, check if you can save the old one.

I can't see any attachment.