Skip to content

Sega Power Base Converter (Master System Converter)

The adapter that runs Master System games on a Mega Drive / Genesis. It's not emulation: the Mega Drive already contains what's needed (a Z80 and a Master System-compatible VDP) — the converter just adapts the cartridge connector. Called the Power Base Converter in the US, Master System Converter in Europe, Mega Adaptor in Japan.

Power Base Converter
Power Base Converter fitted on a Genesis. Photo: Evan-Amos, Wikimedia Commons, public domain.

Identification

Field Value
Manufacturer Sega
Type Passthrough add-on (Mega Drive cartridge slot)
Function play Master System cartridges (Mark III/SMS) on the Mega Drive
Variants Power Base Converter (US) · Master System Converter I / II (EU) · Mega Adaptor (JP, + My Card slot)

Why it works (no emulation)

The Mega Drive is 8-bit backward-compatible by design:

  • Its Z80 (normally for sound) can act as the Master System CPU.
  • Its VDP 315-5313 includes a Master System-compatible mode (the MD VDP is a superset of the SMS / TMS9918 VDP).

→ In "8-bit mode", the Mega Drive natively runs a Master System game. The converter just physically adapts the slot (cartridge pinout/format) — no emulation chip.

Variants

  • Power Base Converter (US) / Master System Converter I (EU): the large model, for the Mega Drive / Genesis Model 1.
  • Master System Converter II (EU): a compact version, compatible with the Mega Drive 2 (the MD2 slot has a different shape → the large model doesn't fit).
  • Mega Adaptor (JP): adds a My Card slot (Sega Card) on top of cartridges.

Limits to know

  • No FM sound: Japanese SMS games with a YM2413 (FM) chip play in PSG only (the Mega Drive lacks the SMS FM chip).

  • No Game Gear (different format and screen).

  • Model 1 vs Model 2: check the right converter for your Mega Drive.
  • Region: SMS region logic can matter depending on the games.

Installation

None: it's a passthrough. Insert it into the Mega Drive cartridge slot, then the Master System cartridge into the converter. Power on → 8-bit mode.

Faults (rare)

The converter has no active electronics → almost nothing to repair. The only common fault is a bad contact:

Symptom Cause Lead
SMS game not read / crash Oxidised/bent contacts (MD slot or converter slot) Clean both edges (iso alcohol), reseat
Nothing in 8-bit mode Wrong variant (Model 1 vs 2) Check the right converter (see Variants)
"Poor" sound on a JP game No FM (normal) None; an MD hardware limit

Before / after

Criterion Mega Drive alone With the converter
Master System games no yes (native 8-bit mode)
FM sound (JP SMS) — no (PSG only)
Effort — adapter (no soldering)

Modern alternatives

The converter is passive, so there's nothing to "modernise" on it. But you can reach the same goal another way:

  • Mega Drive flashcart with SMS support: a Mega EverDrive (Pro/X7) plays Master System ROMs directly on the Mega Drive (via its Z80) — no converter or cartridges needed.
  • FM sound (JP SMS games): the converter never reproduces FM (no YM2413 on the MD). For FM, play on a real Master System (ideally with the FM mod if export) → see Master System § mods.
  • Video: the picture comes out of the Mega Drive → MD RGB/recap mods apply (see Mega Drive).

Where to find

  • Original Sega converters (second-hand) or community repros.
  • Guides: RetroRGB / Sega communities.

Photos / assets

(To add: Power Base Converter vs Converter II, on the MD, slot.)

Advanced repair

A simple adapter (SMS → Mega Drive): cartridge contacts, little to repair. Methods: PCB fault-finding · Traces & vias.

Sources & attribution

Image:

Review & corrections

How this space is used

Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.

Reading is open to everyone; posting requires signing in with Discord. Reports from the wiki's declared reviewers are handled first; anyone else's are read too, but go through a human before anything is changed.