The Japanese Sega Master System included a Yamaha YM2413 FM synthesis chip along with the standard PSG sound. Many games, some of which were never even released in Japan, contain extra FM sound and music. Installing this board will add FM sound capability to any Master System or Mark III game console. The first post in this thread contains a list of games with FM sound. A switch is provided with the board to disable the FM chip and revert to the PSG sound whenever desired.New in version 2.0
New in version 2.2
The method for region switching (disable the I/O chip with KILLG# upon receiving a write to port 0x3F) is not totally reliable. Approximately 5-10% of consoles do not respond. Hardware version 2.2 fixes this problem with the addition of one extra wire to the installation. In late 2014 there was some extra details discovered about the Japanese SMS sound hardware on detailed in this thread. The benefit is there are no longer 'extra' sound effects playing in Outrun at the start of a race.
|After Burner||Golvellius - Valley of Doom||Scramble Spirits|
|Alex Kidd: The Lost Stars||Great Golf *||Shanghai|
|Alien Syndrome||Hoshi wo Sagashite...||Shinobi|
|Altered Beast||Kenseiden||Solomon no Kagi - Oujo Rihita no Namida|
|Aztec Adventure||Lord of the Sword||Space Harrier 3-D|
|Blade Eagle 3-D||Maze Hunter 3-D||SpellCaster|
|BMX Trial Alex Kidd||Megumi Rescue||Super Racing|
|Bomber Raid||Miracle Warriors||Tennis Ace|
|California Games||Mônica no Castelo do Dragão||Tensai Bakabon|
|Captain Silver||Nekkyuu Koushien||Thunder Blade|
|Casino Games||Out Run||Time Soldiers|
|Cloud Master||Out Run 3-D||Turma da Mônica em: O Resgate ++|
|Cyborg Hunter||Parlour Games||Ultima IV: Quest of the Avatar|
|Double Dragon||Penguin Land||Vigilante|
|Fantasy Zone II||Phantasy Star **||Wonder Boy III: The Dragon's Trap ++|
|Fantasy Zone: The Maze||Poseidon Wars 3-D||Wonder Boy in Monster Land|
|Galactic Protector||Power Strike||Y's: The Vanished Omens **|
|Galaxy Force||Rampage||Zaxxon 3-D *|
|Game Box Série Esportes Radicais||Rastan||Zillion II: The Tri Formation|
|Global Defense||Rescue Mission|
|Battle Out Run|
|Ys US Master System FM sound patch||A patch for the Ys US version to put FM sound back in.|
|Phantasy Star retranslation||Phantasy Star Japaese to English translation, has FM sound intact.|
|Sonic 1 FM||Sonic with new FM music.|
The SMSFM board is designed to plug into the expansion slot of an original model Sega Master System console. To fit the board, first remove the screws and open the console. Plug the SMSFM board into the expansion connector. It fits in the cavity behind the cartridge slot and does not require the plasic cover of the expansion port to be punched out. It is usually necessary to cut away part of the metal shielding for the SMSFM board to fit.
A switch is provided to disable the SMSFM board. This is useful for games which you prefer the PSG audio and a few games that crash when they detect FM sound hardware. The version 2.2 board comes with a three position switch. The third position switches the region of the console to Japan. The region switching feature doesn't work on all consoles. If it doesn't work please see instructions for adding the extra region switch wire towards the bottom of the page.
Installation requires some soldering for audio mixing. A capacitor in the audio circuit is removed and a two core shielded cable soldered into its place. The standard (SN76489/PSG) audio signal is sent into the SMSFM board via the white wire, is mixed with the FM sound signal, and sent back through the red wire. The cable shield should be connected to ground to reduce noise. Trimpot RV1 controls the volume of the FM sound only. What follows is a collection of instructions for connecting the audio mixing wires to various different version of SMS main board. Please let me know if you can't find one that matches your hardware.
PAL SMS (original 1986)
Capacitor C48 (10µ aluminium electrolytic type) is removed, the white wire is soldered to the +ve hole and the red wire to the -ve hole. There's a large ground plane nearby to attach the shield. Access to this cap first requires the removal of the voltage regulator heatsink. This is done by first removing the screw on the 7805 voltage regulator with a long shaft screwdriver, then unscrewing the two screws holding the heatsink to the PCB. Don't forget to reattach the heatsink before you finish!
PAL SMS 2
Capacitor C31, located beneath the video encoder IC, is removed. White wire to -ve, red wire to +ve, and shield to nearby ground point at the -ve leg of C44.
Remove C37, white wire to +ve, red wire to -ve. There's a ground plane around the base of the capacitor so just scrape off a bit of the green stuff and solder the shield to that. The heatsink on the voltage regulator many need to be removed for access (remember to put it back!). Because this PCB does not have plated through holes, soldering cannot be done from the component side.
Note that the diagram below is incorrect, the white/red indicators are swapped around.
Late model PAL SMS (VA3)
Remove C62, white wire to -ve, red wire to +ve. The shield is connected to a nearby ground plane - the leg of C59 looks like a good choice.
Brazilian Tectoy SMS (original version)
Locate CI-5, the 315-5124 VDP. Find the trace running from pin 10 and cut it close to the IC. Solder the white wire to pin 10 and the red wire to the positive leg of C45 (that's where the trace goes). I also have a circuit diagram for reference.
Original NTSC SMS (1986)
Remove capacitor C49, located left of the centre in the photo below. Solder the white wire to the +ve leg hole and the red wire to the -ve. Solder the shield to the nearby ground plane or the RF modulator's metal casing.
French M4 SMS (no video encoder, requires the Adapteur RVB)
Remove the yellow wire between the place for C37 and the place for IC9. Solder the white wire to the +ve leg hole of C37 and the red wire to IC9 pin 9. Solder the shield to the nearby ground plane (scratch off the green) or to pin 1 in the place for IC9. Because this PCB does not have plated through holes, soldering cannot be done from the component side.
Generic SMS (those not listed above)
Trace the audio signal from both the RF modulator and A/V port (if there is one) until they meet at a common point. Trace the audio signal back further (it may go through an opamp or audio buffer inside the video encoder IC) until you find an electrolytic capacitor in the signal path. White wire = input to SMSFM board, red wire = output. Find a ground connection close by and attach the shield. Keep in mind that the input and output are electrically the same as those on a stereo system. There's no reason why standard phono sockets can't be attached and the mixing done with external leads.
This is simply a board without a 50 pin edge connector fitted. In order to install the board into a SMS2 or Mark III you will need to do a bit of soldering.
In addition to the audio mixing, the solder in version requires 18
wires to be connected between the SMSFM and the Sega motherboard. The
type of wire using is not critical. Use what you are comfortable working
with, thin wire is usually easier.
Solder diagram for PAL SMS 2 (updated)
KBSEL# is unused and should be left unconnected.
See the etim online shop for price and availability.
Version 1.0 - 2007
There was a small problem with this board which made it
incompatible with a few of games. Read this
discussion on the SMS Power forums for more information
and a fix. Many boards also contained a defective YM2413 sound
chip, read more about it here.
|Version 1.1 - 2009
|Version 2.0 - 2012
Logic Equations (AHDL)
Version 2.1 - 2014
18/2/15 - Removed some info about old versions of the board. Rearranged the page a bit. Added details for the V2.2 board, the game compatibility list, and instructions for the extra wire for region switching.
2/4/14 - Added information about reliability of region switching, link to shop.
15/2/14 - Revised time when new stock is expected.
17/11/13 - Run out of stock.
20/7/13 - Added diagram for French M4 board revision.
13/5/13 - Shop is open again.
26/4/13 - Shop is temporarily closed.
26/1/13 - Added information about V2.0 + shop + diagrams for the audio mixing in the Brazilian Tectoy SMS.
12/8/10 - Added note to NTSC SMS instalation instructions, I'll make a correct diagram one day when I have time.
29/8/09 - Updated with details on the new v1.1 board.
10/1/08 - Page created