Controls & Coin

The Jammafier has a very rapid update frequency (around 350Hz) which makes it practically lag-free.

Cabinet signals on Jammafier

JVS IO-board / Cabinet	Jammafier Game Connector	Jammafier JST-XH
Test	Test
Service Player 1	Service
Service Player 2	Service
Credit increase, slot 1	Coin A
Credit increase, slot 2**	Coin B
Sticks, button 1 to 3	Sticks, button 1 to 3
Button 4 and 5	Button 4 and 5	Button 4 and 5
Button 6		Button 6

**) Not all IO boards/cabinets have support for 2 coin slots

Kick harness – buttons 4,5 & 6

For games that use an additional connector for buttons, they are available on the JST-XH 6 pin header.  The pin-out is clearly marked on the PCB, and is the same used by RGB on his HAS super-gun.

Coincidentally (not really ☺), JST-XH is used in a lot of RC hobby products, so it’s easy to find something that gets you half-way there.  Just search ebay for “JST-XH 5S”, or “1P5S” and you should find many alternatives.  A length of 30cm should be plenty, and I recommend getting one where the individual leads have different colors. 

JST-XH pin	Function
1	Player 1 Button 4
2	Player 2 Button 4
3	Player 1 Button 5
4	Player 2 Button 5
5	Player 1 Button 6
6	Player 2 Button 6

Selectable output for button 4&5

Some games are programmed in a way that buttons 4&5 must be via a kick connector, but will get confused if they at the same time receive input for buttons 4&5 via the Jamma edge.  This is pretty rare, but you may run into it.  By default buttons 4&5 is output BOTH to Jamma and kick – but this can be selected via the menu with 2 options:

• Buttons 4/5 on both Jamma and JST-XH – default
• Buttons 4/5 on JST-XH only

Namco issues

JVS does not have the notion of coin input, but has a more advanced system where the IO board keeps track of available credit.  For this to translate into Jamma, a coin event has to be emulated by pulsing the coin input on the Jamma edge.  The Namco adapter does this in a way that some games don’t understand/like – most notably the Cave CV-1000 series of PCB’s.

FAQ

I’m getting “No IO, retry x”

Make sure your JVS cable is plugged into the connector marked ‘JVS’.  JVS uses the same connector as USB, which is a major source of confusion, especially on boards like the Jammafier that has both USB and JVS.

I’m getting “Unknown IO”

This is because you are (one of) the first to use the Jammafier with that particular IO board.  Please get in touch so the firmware can be updated and correctly identify it.  

What is the USB port used for?

The USB port can be used to power 5V devices from the cabinet power supply.

Can the Jammafier be used in LCD cabinets like the Taito Vewlix?

Yes – but video will have to go through an upscaler.

I want to use a video processor/up-scaler, but it only has connector X for input, what do I do?

Sorry about connector X, it can be a real PITA.  Your best bet is to find a plain connector X to VGA cable, or make your own.

If you make your own, you can find nice breakout’s on ebay by searching for “VGA MALE BREAKOUT SHELL”.

Does it support racing/gun games?

The Jammafier is digital only, i.e. buttons and sticks via the Jamma connector.  

Why is it called Jammafier?

For lack of a better name – it was originally named JVS2JAMMA, but some people confused this with an IO board for Jamma cabinets.

 

 

Power delivery

JVS and JAMMA have slightly different approaches when it comes to power delivery:

Rail	JVS	JAMMA	Jammafier
-5V	n/a	YES – 2 wires	Generated on-board
3.3V	YES – 2 wires	n/a	Used by Jammafier
5V	YES – 2 wires	YES – 4 wires	Passive  delivery, monitored
12V	YES – 1 wire	YES – 2 wires	Passive delivery, monitored

The Jammafier takes 5V and 12V from your cabinet and delivers it passively.  In addition, it has an on-board DC-DC inverter that generates the -5V needed for some games.  

The Jammafier itself only consumes 3.3V, and will not interfere with 5V delivery.

You need to connect both connectors for the Jammafier to operate properly, and ensure good power delivery to your game.

Warning 

DO NOT connect a Jamma game to the Jammafier before verifying your cabinet delivers correct power.  You can do this by connecting the Jammafier to your cabinet with no game, and verify the voltages on the on-screen voltmeter. 

If the voltages shown on the Jammafier varies a lot between games, it is an indication that the power cables in your cabinet are not thick enough.  With proper cabling, it should not be necessary to adjust the voltage on your PSU when changing games.

Details on power for the technically inclined

To ensure good power to your game, there are basically 2 things that needs to be in place:

• A good power supply that can supply stable voltage for power hungry games (high current)
• Minimal resistance between supply and game

JVS Power

These are the JST-VL connectors and pin-outs specified in the JVS Standard, image is looking at the game.  Although it has a lot of wires, only 5V is of interest when it comes to Jamma games.  Naomi Unversal cabinets use 18AWG wires, so effectively 1x15AWG is available for power delivery. 

What is voltage drop?

If you measure the voltage coming out of your power supply, you may get a different reading than if you measure the actual game.  This is called voltage drop, is caused by the wires used, and the formula is basically just Ohm’s law:

V_drop = IR,

where I is the current your game use and R is resistance of the wires between game and power supply, including return GND wires.

You can’t do much about the current consumption of the game, so the only variable left is the resistance of the wires.  Resistance in wires is affected by:

• Material
• Width
• Length

Thin long wires have higher resistance than short thick ones – and in general you want to try to have them as short and thick as possible.  Using wires in parallel to decrease resistance works well, and is used by both old Jamma and JVS.  For every doubling of wires, subtract 3 from the AWG number:

• 2xAWG24 is the same as 1xAWG21. 
• 4xAWG24 is the same as 1xAWG18 (2xAWG24=1xAWG21, 2xAWG21=1xAWG18)
• 2xAWG18 is the same as 1xAWG15. 

Incidentally, (not really☺), AWG15 has half the resistance of AWG18.  This leads to a couple of rule-of-thumbs:

• 2 x current (power usage) = 2 x voltage drop
• Half the resistance = half the voltage drop

This is a real issue – the game Salamander uses 4.1A, while Cave SH-1 only uses 0.5A.  In the same cabinet, the Salamander game will have EIGHT times the voltage drop of the Cave game.

Namco issues

The Namco JVS2JAMMA has 3 main issues when it comes to power delivery.

• Jamma harness cabling
• PCB layout
• PCB current draw

The wire harness on the Namco uses 4*24AWG cables for 5V, which equals a single 18AWG wire. Although it is pretty short, combined with the PCB layout and the fact that the PCB itself uses 0.5A, it all adds up to it being problematic with power hungry games.

Konami issues

While the Konami does a lot of things right, it was one major fault:

• Single power connector

This effectively means only one wire is used for 5V, and in the case of Naomi Universal – it will be a single 18AWG.  The Konami does not generate -5V, but it has a header that is routed to the Jamma connector – so it is possible to feed it via a “Negatron” or similar device.

Riverservice/RS issues

No -5V, and no header – soldering required if you need it.

Introduction

The Jammafier is a device that enables you to play older Jamma PCB’s in a JVS only cabinet, like the Sega Naomi Universal.  It handles controls, power and audio – but does not touch the video signals.  The intention is to address a few shortcomings of existing solutions, both technically and when it comes to availability – I hope you like it 🙂

Features

• Rapid JVS updates for minimal lag
• Optimized layout for low voltage-drop
• -5V generation
• OLED display for diagnostics, including precision volt-meter for 5V and 12V
• Attenuated audio via two RCA connectors for easy use with cabinet amplifier.
• Raw video /sync, or 75-ohm video and processed sync via VGA connector*
• Buttons 1-5 on Jamma connector
• Buttons 4-6 on auxilary ‘kick’ connector
• MVS remap – ‘Neo Geo layout’ on 6 button panels
• Easy firmware update via micro-sd

*)  VGA connector chosen for convenience and availability of cables. The Jammafier does not touch the video signals generated by the Jamma PCB, and you will most likely need an additional device to modify the video signals for use with a modern monitor. Processed video/sync only available on revision 2.0 and newer.

Disclaimer/Warning

Short version: I shall not be held responsible for destroying your PCB’s or if your house catches fire – check that your game and cabinet power supply is working correctly.  Your cabinet power supply is capable of delivering enough current to do serious damage to everything it powers.

Each time you use the Jammafier, you risk catastrophic failure of your cabinet, Jammafier or game.  You can substantially reduce this risk by:

1. Assuring that every component is working correctly 
2. Assuring that every component is connected correctly
3. Obtain instructions on how each component is operating
4. Never leave a powered system unattended

However, electronics sometimes fail to operate properly – even when properly assembled and operated – so you risk catastrophic failure or fire each time you use the Jammafier.