This is just sharing the project from https://github.com/Board-Folk/MegaCD-Main-BD, and all design credit goes to Cosam and the Board Folk contributors.

The project recreates the main board of Sega’s Mega CD / Sega CD add-on for the Mega Drive/Genesis. These boards are often ruined by leaking capacitors and batteries. Three revisions are covered: 837-8015 (MCE1), 837-8015-01 (MCE2) and the 837-8952 Export board for MCE2 or MCE3. They were reverse-engineered from the original schematics and scans of the copper layers, and all combinations are reported as verified working.

Two small Zip-to-SOJ DRAM adapter boards let the SOJ DRAM from later boards replace the hard-to-find ZIP chips on the Japanese revisions. The boards are meant to be populated with chips taken from a donor board, so you need to be comfortable with fine-pitch SMD rework. The main boards are 4-layer, 188.9 × 92 mm.

WARNING

Stale gerbers: they date from 2023, and the KiCad files were edited later. Placement is identical, but the paste layers put solder paste on all 60 edge-connector fingers. Tell PCBWay there should be no paste there.

Wrong placeholder: the Rev0 and Export silkscreens print the PCB order-number placeholder , which PCBWay would print literally.

RAM adapters: order them as 2-layer boards. I traced the connections and the 2-layer gerber set is complete.

Red BOM rows: the README’s parts list and the KiCad files disagree on several capacitors. The biggest are C1 (1uF vs 1000pF) and the 22uF/22nF swap on C52 and C8/C13. I used the README values; measure your donor board to confirm.

Export board options: the BOM defaults to the MCE2 chip (IC17 fitted, R10 empty) and R12 fitted rather than R11. Never fit R11 and R12 together.