A dying first release Mega-CD 1

[Dr.Wily]

I have the very first shot of a japanese Mega-CD 1. But one day without any reason it stop working.

After long search, I did not find where is the failure. When I powering up the Genesis I have a blank screen, however the tray start to close (when it's open). No BIOS screen, no sound.

- All fuses are OK
- power\sound board works (I tested it on another MCD)
- all leads are good
- the BIOS works to.

The issue may come from the interface board between Genesis and Mega-CD. It use a cable plug directly on a crystal oscillator on the MCD motherboard.
But I can't test the motherbord on another MCD because it's specifics.

I took some pics for understanding :

The motherboard parts side
The motherboard solder side
MB Memory chips
crystal oscillator sub board
sub board connector
interface board part side
interface board solder side
closer view of interface board's chips
closer view of solder side + grey cable
closer view of solder side + black cable

It would be nice if someone can save this first release of this Mega-CD. Plus, his BIOS is not zoned. It works on both 50Hz and 60Hz Genesis.

[dead_screem]

The first and only thing I would suggest, since I've had this problem before. is to clean the edge connector of the Megadrive where it connects to the Mega-CD, You'll have to take the Megadrive apart to get at both sides of the edge connector though. Don't clean it with straight rubbing alcohol. youmay do more harm. Use a standard Pink Pencil eraser (no funny colored ones as they are usually another material) and rub the contacts, you'll see the eraser turn black from the dirt, rub the eraser on a clean piece of paper to clean the dirt off and repeat till both sides of the edge connector are shiny. Repeat for the edge connector on the Mega-CD mainboard where it connects to the connect board.

his BIOS is not zoned. It works on both 50Hz and 60Hz Genesis.

Are you sure about that statement? There is a dump of a japanese Mega-CD that will Run with NTSC-JP, PAL-EU and PAL-ASIA (HK and Taiwan) but NTSC-US (the Genesis) is locked out.
In any case, do you have the means to dump that BIOS? Either with Mask of Destiny's cable or by dumping the EPROM with a programmer. I'd like to know exactly which BIOS matches with that part number EPR-14088 B.

[APE]

Check the caps? I revived a Game Gear the other week by pulling all the old ones and replacing them with new ones along with the cold cathode tube. This baby is gonna get me ~8 hours of battery time now!

If you like I could take a look at your system free of charge if you just pay for shipping both ways. Studying for an electrical engineering degree and I have lots of experience with older SEGA hardware (revived a JVC X'EYE a few months back. Splendid design!). I don't see anything obviously wrong with it but I have the hardware here to replace chips if it is necessary. Also have the code for a multi-region BIOS as well.

[Dr.Wily]

The first and only thing I would suggest, since I've had this problem before. is to clean the edge connector of the Megadrive where it connects to the Mega-CD

I have already done this, and tested with several MD\Gen. Whenever same result, blank screen.

Are you sure about that statement? There is a dump of a japanese Mega-CD that will Run with NTSC-JP, PAL-EU and PAL-ASIA (HK and Taiwan) but NTSC-US (the Genesis) is locked out.

Oh, yes I am. when it was still working, this Mega-CD started with all MD\Gen (50Hz, 60Hz japanese, euro and US). However, it's zoned for games.

Check the caps?

Yes, look at the motherboard pics, it's not genuine caps.

If you like I could take a look at your system free of charge if you just pay for shipping both ways.

Interesting ! PM sent ;-)

[dead_screem]

Oh, yes I am. when it was still working, this Mega-CD started with all MD\Gen (50Hz, 60Hz japanese, euro and US). However, it's zoned for games.

It would appear then, that that BIOS, "EPR-14088 B" as labeled in your pics, is un-dumped If you end up sending it to APE, maybe he can dump it? (That is if you can't). as in the thread by segaloco he Mentioned he can dump BIOSes.

As I, and loco as well, would greatly like to what BIOS matches that number "EPR-14088 B", especially seeing as it would appear that its not dumped at all yet.

[raylyd]

it could be your sega cd motherboard needs cleaning i had the same some time ago hope it gets fixed

[ASSEMbler]

Most likely the caps, or a cold solder break.

[raylyd]

yeh i have seen that in a few mega cds only model ones that have smt caps

[Dr.Wily]

Oh, this topic raise for his grave ;)

I had to sent sent this Mega-CD to APE, but I never had the time to do this. But if APE (or someone else) is always ready I can send the Mega-CD now. PM me.

[raylyd]

hi mate i can have a look at it for you as you dont have the time let me know i can do it for you cheap as i have lot of new bits and bobs for repairs i would test before reshiping pm me if you want and its japanse it rare but please send a mega drive with it as i dont own a jap mega drive and if its caps its free for you as these are rare i have all cabes to test them and repair them i have most tools

[Dr.Wily]

Some news after resuming fixing this non working Mega-CD.

This jap Mega-CD have a socketed BIOS, then I tried to swap with diferents bioses like PAL and US 1.x BIOS.

The facts : (all bioses ROM are safe)

- Jap MCD motherboard with jap BIOS : not working
- Jap MCD motherboard with US BIOS : not working
- Jap MCD motherboard with US BIOS : not working

- US / EURO MCD motherboard with US or EURO BIOS : works
- US / EURO MCD motherboard with jap BIOS : not working

Why this japanese BIOS refuse to run on a safe MCD1 motherboard ? Any clue ?

[l_oliveira]

From a quick look at the picture, I can tell the board suffers from serious corrosion problem.

The capacitors already leaked. You look around the pins of the SMD capacitors, you will notice that the solder is "blackened" which means they either leaked or are in the process of leaking.

Around C11 at the bottom of the picture, close to the SUB-CPU workram, nearby the clock generator patch board (This little board does generate some sort of clock for the "patch" chip which is on the breaker board and only very early units have. Of course if you don't connect the wire the whole thing won't work properly...) one can easily see the corrosion on the copper...

About some BIOS not working, it seems that corroded copper traces could cause erratic behavior and since each bios work differently (due to cosmetic changes on the boot screen and logos) it's likely that simpler bios such as the PAL or JPN bios have a better chance of working on a broken board.

US BIOS has a tighter code because it uses PCM and FM on audio playback for the intro song and has more moving elements on the screen. That means it must use more memory.

I own a MD-CD which is identical to yours and every single bios I tried on it (even Wonder MEGA1 BIOS) worked fine on it. Only a few bios would boot but fail before launching discs (WonderMEGA2/Xeye) or not work at all as the Laser Active bios (Hardware is way too different for it to work lol)
:thumbsup:

[APE]

I'm still able to do capacitor swaps and what not, but l_oliveira is right, that corrosion is really ugly.

[sayin999]

I opened up my mega cd and noticed it was a socket-ed bios that looked like it was an eprom with a sticker over it with printed letters determining what version is it. Any reason they used socket-ed bios for the japanese mega cd?