Yes, the weird daughter board does indeed have an oscillator and control chip on the underside, with some tape on top to protect the protruding legs etc.. It also has a small 2 pin connector that goes to points on the Megadrive/MegaCD edge connector board, which in itself is much changed in later revisions. Looking at later boards it looks like they have been updated to include these parts.. Early SEGA consoles were almost like prototypes that they released in a hurry. But it's easy to forget that SEGA was at the cutting edge with this stuff.. And I suppose pressure was always there to get boards up and ready for sale..
What the daughterboard does is tap the 50mhz clock, divide it and send to the "patch" chip on the connectors board. Two wires go from the connector board into the daughterboard you mentioned. It's a quick fix for a bug on the big logic chip. Newer units had it resolved so there is no chip on the connectors board. It will not operate without the small chip that is on the connector board. All you will get is a black screen if you try to use the PAL connector board.
OK i had a Dev mega CD motherboard would not work with a retail mega drive i though the board was no good but waited until i had other unit to test on other mega CD Dev unit and worked very same fault you have with yours. The Sega 315 chips on the mega drive there's a few different ones out there. If you want me to test the board on my end let me know? Or send the board to the great l_oliveira for a very deep fault finder i have a few motherboards i need to send him that have while sceen and black screen of death after cap replacement's Try one more thing i replaced some capacitors on a mega CD motherboard and started to smoke so i removed all the 10uf caps and board worked fine so try that and let us know i am very like trying to help out any sega fan owner.
Thanks for the offer bart_simpson, funnily enough i did try it with no caps on.. still didn't work though. I plan to fully clean an re-flow the entire board over the weekend, and go from there. I have a spare PAL Mega CD to raid for parts and may end up using a working PAL board with the NTSC eprom and case etc.. On closer inspection of the connecter board mentioned above by l_oliveira, someone had previously re-attached the black and grey wires and overheated one of the "resistor arrays"... maybe this is a contributing factor.. You can see the melted plastic of the connecter, and just about see the heat damage to the "resistor array"!! [/IMG]
What he means, is that he never seen a board like that with a active chip and wires on it. As I've stated multiple times, the early JP MEGA-CD has hardware fixes applied by the extra chip on that board and the two wires that connect to the daughter board on the mainboard are to clock this small chip up. The JP mainboard will not work with a EURO/USA CONNECT BD, neither the EURO/USA mainboard will work with the pictured CONNECT BD.
PAL/NTSC Hybrid I decided to re-cap and repair (battery holder missing) a extra PAL board i have, and then de-solder the ROM from the board, and solder on a socket. This let me install my NTSC/JP eprom from the troublesome one i have.. and it works perfectly. I am keeping the NTSC/JP board and will attempt another repair, but for now i'm happy to have a fully working NTSC/JP Mega CD.. cool. Thanks everyone for your suggestions and advice. Here is a pic of the Hybrid...
That's not a Japanese MEGA-CD. It's for southern Asia (HK and surrounding area). If you put it on the wrong console it refers to itself as a "PAL-COMPATIBLE MEGA-CD for use in Southern Asia" ... The hardware is exactly the same as the Japanese unit but the bios is a newer version. Also, that is the exact bios I used on my region free hack for that specific model (EPR-14563H).
Thanks l_oliveira, I stand corrected. It does however work fine with my un-modified Model 1 NTSC/JP HAA-2510 Mega drive. I admit, it's not really a TRUE NTSC/JP setup, but the Megadrive and CD were both bought for silly money because they were broken. Mega drive was £5... Boxed...ha ha ha..:highly_amused: and the Mega CD was £30, plus £10 for the parts i needed.. Besides that, they look awesome... Update.. Japanese Only NTSC Model No. HAA-2910 South Asian (HK) NTSC Model Mo. MK-1690-11 This will make them easier to tell apart if you come across one and aren't sure
Even if it was through a short cut, congrats on reviving that wonderful machine. Now grab the region free bios, burn a new EPROM and put on it. It will play the PAL games too if you do so (I recommend you connect a PAL MEGA DRIVE to it while using PAL games, for compatibility reasons (the region free bios has the region lock message removed and will work with any MEGA DRIVE/GENESIS console).
PAL "16-BIT" is silver and small. Asia "16-BIT" is large and golden. Also the MEGA DRIVE logo has a different font on it.
Don't forget that there is no PAL output at all on this model megadrive.. Rf module is completely absent.. I have 4 compatible EPROMs and loads more sockets, but no longer have access to flashers anymore.. job change.. Shame.
The top AND bottom case are different, as i said there is no hole for the PAL RF connector because it does not have one.. If you have a NTSC/JP "looking" Mega drive with a PAL RF connection its a PAL Asian version.. NOT a NTSC Japanese one..
