Sega CD systems repair thread

[Guntz]

Could you take pictures of these wires? Also the revision of the main board on your Sega CD (where the BIOS goes). This is news to me, I don't remember seeing patch cables. They might explain why my Sega CD has never shut off when the Genesis does, only if you plug a cartridge in and turn the Genesis on. The total BIOS crash only came up after a power black out.

[SegaSonic91]

I was referring to a Japanese MEGA-CD with patch board. I was fairly certain they revised that by the time the SEGA-CD came about. I do have some photos, I will check them to see if they show what I am referring to clearly enough.

Edit: it does not show the connection board but shows the patch board. I will get a pic of connector as well.

Edit 2: Bah, stupid photo upload keeps failing. I used another photo which is not mine but shows what I am referring to.

image.jpg

[qzack]

Did you get rid of the one with bad ram?

Yes. As a matter of fact the board stopped working altogether. I guess the Ram going was the first sign of trouble.

[PJEJJ]

I have a Model 1 Sega CD with a KSS240. I have adjusted the pots a ton of times and I can't get it past the disc detect stage. I have adjusted it to where the lens keeps raising and the disc won't spin at all, then to the point where the laser detects the disc, disc spins, and the laser reads a little of the disc and it just continues to spin the disc like nothing is wrong. I can manually move the gear that moves the laser sled all the way to the outside and it will readjust to the normal start position without problems. I made a video that shows what it is doing. The bios screen asks for a disc and when one is placed in, the bios movie keeps playing and the game never loads nor does it display any text under the attract video.

Any thoughts?

https://dl.dropboxusercontent.com/u/...%2002%20PM.mov

[SegaSonic91]

Are you using an official psu? If it is not official, it causes problems. Are you trying to load CD-Rs or original? As I discovered today (I made a post about it in the mega-cd forum), not having the psu made for the particular model/version really does cause problems. I was using an official PAL MEGA-CD psu with my Jp systems and it will not read CD-Rs. Using the Jp psu with a step down there was no problems. Very, very weird and goes along with other weird design decisions I guess.

Edit: Video finally loaded, I see it is a real game. The psu can still cause issues. If it's all original, could just be a dying laser. Replacements are cheap and easy to find. Following omp's instructions in this thread, it is extremely easy to install too. Otherwise, other problems could be the dreaded caps!

[PJEJJ]

Are you using an official psu? If it is not official, it causes problems. Are you trying to load CD-Rs or original? As I discovered today (I made a post about it in the mega-cd forum), not having the psu made for the particular model/version really does cause problems. I was using an official PAL MEGA-CD psu with my Jp systems and it will not read CD-Rs. Using the Jp psu with a step down there was no problems. Very, very weird and goes along with other weird design decisions I guess.

Edit: Video finally loaded, I see it is a real game. The psu can still cause issues. If it's all original, could just be a dying laser. Replacements are cheap and easy to find. Following omp's instructions in this thread, it is extremely easy to install too. Otherwise, other problems could be the dreaded caps!

Yeah, sorry I probably should have posted to youtube or something. I recall I swapped the laser with my Model 2 Sega CD (also a KSS240 laser) and it had the same issues. I'm fuzzy on that because I really haven't touched this model 1 since 2012. I am using an official Sega power adapter for a model 1 Genesis/Sega CD. I was just wanting to make sure there wasn't something I am entirely missing in lieu of replacing all the caps. It isn't hard, just tedious.

Thanks for the insight though. Guess I'll start doing a cap count :/

[SegaSonic91]

Hmm, that is weird if you already changed the laser. Hopefully the caps can sort the problem. I am dopey and don't know how to link one post, but scroll down the link below from within this thread and you will find a full cap list for the model 1. I am just wondering how one goes about re-capping the CD board o_O

http://www.sega-16.com/forum/showthr...r-thread/page7

[greenone]

Evening all - first off, thanks to everyone in this thread for the guides they've posted. I've managed to fix one Model 1 so far by replacing the fuse and disassembling/reassembling the tray mechanism. Great to have it working.

I picked up a second Model 1 for a good price because it wouldn't power on - replaced the fuse, and now it powers on, but I only see the startup screen for a fraction of a second before the screen goes black. The audio keeps playing, however, and I can hear the laser moving around and the CD spinning. The tray won't open or close, and pushing reset on the unit doesn't do anything, nor does hitting start on the controller. It's like the BIOS isn't loading, so it can't move past that startup screen.

This happens whether I use the AV cable or the RF out from the Genesis. The Genesis plays games just fine when detached from everything else, and displays video just fine from another Sega CD that I fixed up previously. I'm using all genuine parts - adapters and cables - and the board on this one looks very clean compared to the other one I have, which works despite multiple leaky capacitors and one that's missing completely.

I had someone say it might be bad capacitors, but given my success with the other model I'm not inclined to believe that's the case. Here's an imgur gallery of the two boards in case I'm missing something - thanks in advance for any help!

https://imgur.com/a/b16Tt

[Guntz]

My SCD Model 1 has the exact same problem, BIOS screen appears for a split second, then goes to black. There's no music from the Sega CD, only the Genesis (both play half the BIOS music).

I've tried replacing the BIOS chip in mine, same issue. I really have no idea what the cause is. Maybe one of the RAM chips is bad...? There's other possibilities too, none are particularly pleasant. The SCD1 main board requires an insane amount of soldering iron heat to do anything on.

[LaC]

Evening all - first off, thanks to everyone in this thread for the guides they've posted. I've managed to fix one Model 1 so far by replacing the fuse and disassembling/reassembling the tray mechanism. Great to have it working.

I picked up a second Model 1 for a good price because it wouldn't power on - replaced the fuse, and now it powers on, but I only see the startup screen for a fraction of a second before the screen goes black. The audio keeps playing, however, and I can hear the laser moving around and the CD spinning. The tray won't open or close, and pushing reset on the unit doesn't do anything, nor does hitting start on the controller. It's like the BIOS isn't loading, so it can't move past that startup screen.

This happens whether I use the AV cable or the RF out from the Genesis. The Genesis plays games just fine when detached from everything else, and displays video just fine from another Sega CD that I fixed up previously. I'm using all genuine parts - adapters and cables - and the board on this one looks very clean compared to the other one I have, which works despite multiple leaky capacitors and one that's missing completely.

I had someone say it might be bad capacitors, but given my success with the other model I'm not inclined to believe that's the case. Here's an imgur gallery of the two boards in case I'm missing something - thanks in advance for any help!

https://imgur.com/a/b16Tt

Weird, I am having the exact same problem that just started today.
Screen appears for a second then goes to black, and then music keeps playing. I tried to press start to load the game in the drive, but nothing happens.
I recapped it like 4 months ago with a cap kit from console5, back then it was having corrupt video issues and lockups. And it has been fine since. But today, it's like it just decided to stop working.

[FuturePrimitive]

^ Do you guys think this is a Model 1 specific issue? Hopefully a solution can be found for the preservation of these Model 1 CD systems. Makes me worried since I'm in the market for a Model 1.

[greenone]

My SCD Model 1 has the exact same problem, BIOS screen appears for a split second, then goes to black. There's no music from the Sega CD, only the Genesis (both play half the BIOS music).

Stupid question as I was a Nintendo kid growing up - how can you tell the CD BIOS music from the Genesis BIOS music? I thought the Genesis just said "Sega" on startup.

It's been recommended that I test the continuity through the board - would I just do that from the ribbon connector to the expansion port pins? I assume there's no easy way to tell if a capacitor is still good other than a visual inspection. I do have a cap replacement kit, which I bought for my first Sega CD. On that one, C44 is completely gone and several others have clearly popped, but it works fine. I may also try simply swapping the boards to see what happens in the absence of other ideas.

[Guntz]

Stupid question as I was a Nintendo kid growing up - how can you tell the CD BIOS music from the Genesis BIOS music? I thought the Genesis just said "Sega" on startup.

Only a few Genesis games have that SEGA voice clip. The Genesis itself has no BIOS (unless TMSS counts).

On the Sega CD BIOS, there's music that plays. Both the USA Model 1 and 2 music tracks are played by both the Genesis (YM2612 + PSG) and Sega CD (PCM). Unless you know what the whole track sounds like with both consoles working, you wouldn't easily know if only half the track is playing or not. On the SCD Model 1 at least, the Sega CD part of the music will sound like the backtrack, the Genesis does the melody primarily.

It's been recommended that I test the continuity through the board - would I just do that from the ribbon connector to the expansion port pins? I assume there's no easy way to tell if a capacitor is still good other than a visual inspection. I do have a cap replacement kit, which I bought for my first Sega CD. On that one, C44 is completely gone and several others have clearly popped, but it works fine. I may also try simply swapping the boards to see what happens in the absence of other ideas.

Personally, I wouldn't do the capacitor replacement unless it would actually fix the BIOS problem. Changing caps can be tedious and you might end up wasting caps on an unrepairable board.

I'm gonna wait until someone finds a possible solution.

[LaC]

^ Do you guys think this is a Model 1 specific issue? Hopefully a solution can be found for the preservation of these Model 1 CD systems. Makes me worried since I'm in the market for a Model 1.

Well Model1's just tend to be more flakey.

[greenone]

Only a few Genesis games have that SEGA voice clip. The Genesis itself has no BIOS (unless TMSS counts).

Ok, that's what I thought. Thanks for the clarification and explanation!

If anyone else has an answer to the continuity question, I'd appreciate it.