MegaCD-Connect-BD-Remake

This is the Schematics, PCB and Logic for the Mega-CD Connect BD Targeting the 315-5547 (MCE V1) MegaCD.

It is to replace the 837-8327-01 IC BD MEGA-CD CONNECT BD with a failed ASIC to the older Logic version of the board that has the Peel IC.

The board is not a clone, rather a remake as i do not have access to an original logic board version to do an exact replica of traces.

The Gerbers have been created using the recommendations from JLCPCB.
This board uses a GAL22V10 to achieve the same logic functions as the Peel IC. Jed file is provided. Use a MiniPro to write the Jed file to the GAL Chip.

Note:- TESTED V2.0 and this worked, but now made V2.1 and is UNTESTED

Version 2.1 Changes:-

Moved /TRDIR from PIN 23 to PIN 15, This should make it compatible with the GAL20V8
Added GAL20V8 Logic
Updated Labels for Tree House Connection, TH1 and TH2

The software i used to make the Jed file was GALasm. It can be downloaded from here https://github.com/daveho/GALasm

Only source files is provide, so you will need to compile GALasm first. I used MacOS to do this, Linux should work and maybe Windows ???

Once GALasm is compiled, use the following command to compile the Logic into a Jed file from within the GAL22V10 folder.

galasm ./GAL22V10.pld

1. Post

There is a slight modification required to make the PCB fit in the original housing.

This Post would need a little snip to allow the GAL chip pins to sit correctly in the housing.

2. Tree House J3

If you use a Pin Header, you will need to bend it slighly inwards otherwise it will not fit inside the MegaCD.

Reference	Value	Quantity	DigiKey
C1 - C6	100nf	6	CL31B104KBCNNNC
IC1	GAL22V10B	1
IC2, IC3	74HC374	2	296-1592-5-ND
IC4	74ACT10	1	CD74ACT10E-ND
IC5, IC6	74HC245	2	296-1584-5-ND
RN1, RN2	9X-1-472LF (4.7K)	2	4609X-101-472LF-ND
J1, J2	CONN EDGE DF 60POS	2	A112392-ND
J3	2 Pin Header 2.54mm	1	609-4434-ND

Thanks

With thanks to @fabiodl for decoding the logic of the Peel IC

Use at your own risk. I accept no responsibility.