Anyone know how to Fix a Sega CD 1st Gen?

bustedstr8

Trollbox Trade Federation,
Joined
Oct 15, 2007
Posts
943
You could ask JetBlue, I know he works on a lot of CD based systems.
 

Xian Xi

JammaNationX,
Joined
Dec 1, 2005
Posts
27,702
Ah. Gotcha. What's going on with it?

I sold my working Model 1 Sega CD, shipped it down to Florida and buyer has not been able to get it to work. When it arrived the tray was funky which he says he was able to fix but the system will not read discs. He believed it to be a bad laser so he ordered the replacement and it still won't read discs. I suspect something got jarred in shipping since it messed up the tray so something else could be loose or something.
 

HMG

H = Heinously, M = Massive, G = Gonad,
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Apr 3, 2011
Posts
4,967
It probably suffered some sort of alignment problem. I'm not part of the lower 48 so I can't help.

I'm surprised though, I thought you could fix anything Xian Xi.
 

Xian Xi

JammaNationX,
Joined
Dec 1, 2005
Posts
27,702
It probably suffered some sort of alignment problem. I'm not part of the lower 48 so I can't help.

I'm surprised though, I thought you could fix anything Xian Xi.

It's one of the things that I don't want to ship back and forth because of the shipping cost so I'd rather have someone with experience look it over.
 

indibil

Timid Neo Newbie
Joined
Sep 2, 2021
Posts
3
Hi! I am writing to you from Spain, sorry if my English is bad.

I recently bought a MegaCD 1 JAP, first units, the ones that have a sub-board with oscillator into upper of the main board, but the interconnection board with the megadrive, where the two cables that go to this sub-board come from , it is already smd, without metal cover.

It was sold for parts, it didn't work. I've done some repairs but I can't get anything at all, no LEDs, no image, or cdrom movement.

Let me tell you. I first detected blackened TR4, and have replaced it with another darlington. The fuse was fine. I have also changed the regulator for a 7805, and on the power board I have changed the caps that affect only the power supply, I have not touched the sound caps. I don't know if any can also cause it not to start.

With this repair I did not get anything. On the main board I added a led with a resistor connected directly to 5V, and when I turn on the megadrive it lights up, then the power-board works well, and the signal from the megadrive, to start it, also reaches it.

Later I discovered that the flat-cable that connects the main board with the cd-unit was not the original, instead of 21 pins it was 20 pins, and at the end of the cd-unit it was destroyed, perhaps creating a short on some tracks . I ordered a new one. The unit does not work with the new cable either, nothing at all.

The next step has been to change all the caps of the main board and the connection-board for new ones, I have used smd tantalum capacitors.

Also not working, no new symptoms.

As the main board has a socket for the BIOS, from factory, I have programmed a new bios, and it does not start either.

If the cd-board is damaged, but not short-circuited, can it cause the megacd to no longer start? or would this just not work but the main board would boot?

The other caps of the power-board, which do not affect the power supply, can they cause the megacd to not start at all?

No cap had lost liquid, on any board.

The connection board with the megadrive looks in very good condition, but there is a square chip in the middle that manages some aspect. Could it be that the connection board gives a signal for the power-board to start, but prevents communication with the megadrive? If I put a cartridge, it runs normally, as it would with a functional megacd, it does not disable the megadrive.

I am totally lost. Can you help me?

Thanks!!!
 

indibil

Timid Neo Newbie
Joined
Sep 2, 2021
Posts
3
Yesterday I did new tests, without result. I changed the remaining caps to change on the power-board, and I did not have any improvement. Then I did a test. I opened the CD tray manually, and then when turning on the mega drive, the tray closed itself, so I deduce that the cd-board still works. Could it be that the problem is in the connection board between the main-board and the mega-drive? What problem can there be? there is only a square chip and some capacitors. Nothing seems damaged there, the tracks look good.
 

Atro

Who?,
Joined
Jan 30, 2002
Posts
8,822
Mine was totally pitch black. I desoldered the BIOS and installed a socket with a new one.

It now works like a charm. You might have a different issue tho.

Also, this is a NG repair subforum. Try to open a new thread in the right channels the next time instead of necrobumping ;)
 

indibil

Timid Neo Newbie
Joined
Sep 2, 2021
Posts
3
Mine was totally pitch black. I desoldered the BIOS and installed a socket with a new one.

It now works like a charm. You might have a different issue tho.

Also, this is a NG repair subforum. Try to open a new thread in the right channels the next time instead of necrobumping ;)
Thanks for the reply, i have try another bios and the same problem. Include i have test another bios with a everdrive, and nothing, black screen and leds off.
 

Atro

Who?,
Joined
Jan 30, 2002
Posts
8,822
Thanks for the reply, i have try another bios and the same problem. Include i have test another bios with a everdrive, and nothing, black screen and leds off.
Your power circuit board can be faulty too. There's not so many components on it. You should try to replace those. It shouldn't hurt.
 
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