Everything you’d want to know about Sega Type II IR Light Guns. Part: 2 LED Boards

In Part 1 I discussed a high level overview of how the Sega/OHMIC IR light gun setup works. Here in Part 2 I’m going to start breaking down the technical details.

As stated in part 1 there are essentially 3 parts to this setup,
1. A chain of 10 or 12 Addressable IR LED boards explicitly positioned around the parameter of the display
2. IR motion sensors in the gun housings.
3. The “Gun Sense” board (essentially the Gun IO).

In this Part I’m going to discuss the LED Boards.

Pinout and Wiring

The IR LED modules have two 6-pin connectors. The connectors, one marked “IN” and one marked “OUT”, are pinned identically. The LED modules are designed to be “chained” together with the output of one module going to the input on the next. The input on the first module comes from the Gun Sense board and the output on the last module is left empty; not connected to anything. Interestingly the LED output connector on the gun sense board is pinned backwards from the connectors on the LED modules:

These use a 6-pin JST XH family connector

The function of each pin isn’t documented (the manuals simply reference the data pins as “A”, “B”, and “C”) and unless you’re reverse engineering the LED board you simply need to follow the pinning in the picture above. It’s worth noting though that the power pins follow standard Sega wire color. On the LED board connectors the pinout is as follows:

  1. GND (white)
  2. A (orange)
  3. B (green)
  4. C (blue)
  5. +5V (yellow)
  6. +12V (red)

LED Positioning Around the Monitor

Depending on the Gun Sense board, there could be 10 or 12 LEDs in a chain. In-fact Jurassic Park The Lost world was the only game that shipped with 12 LED modules and every subsequent game has used only 10. Despite this fact most of the gun sense boards actually have a dip switch to switch between the 10 and 12 LED configuration (more on this in the Gun Sense Board section).

The 12-LED configuration must be in the pattern below with “1” being the first board in the chain after the gun sense board and “12” being the end of the chain.

LEDs 4, 6, 10 and 12 are what mark the corners of the screen. Typically these corner LEDs are rotated at a 45degree angle though this is likely for wiring purposes as the angle of the LED board is irrelevant as long as the sensor in the Gun can see it.

The 10-LED configuration must be in the pattern below with “1” being the first board in the chain after the gun sense board and “10” being the end of the chain.

On the 10 LED arrangement you might notice that LEDs 4, 5, 9 and 10 are in the corners and there is no longer any LEDs on the left and right sides of the screen. In both configurations the LEDs should be evenly spaced and aligned parallel with the edge of the screen.

IR Wavelengths

One other thing you might Notice in the photo above is that you can see a faint red light in each of the LED locations. Indeed these IRs LEDs output light that dips slightly into the visible spectrum. It’s enough that in a dimly lit room on close inspection you can easily verify if your LEDs are powering on.

OHMIC supposedly used custom LEDs with a non-standard wavelength to prevent 3rd parties from making and selling replacement parts. I actually tested several of the LED boards against a Light Spectrometer to determine the output range, which you can see below.

Most games came equipped with small Tinted plastic windows that would be placed in front of the LED module. These are designed to let only IR light through so they appear to be a very dark red, almost black in color and they mostly only exist to make the arcade machine look “cleaner”. I’ve found that by NOT using these windows the range in which the guns work can be improved quite a bit.


There is not much that can go wrong with the LED boards, they’re pretty robust and the circuit is simple but the LEDs failing is usually what kills them.

Given that you can actually see some faint red light if they’re powering on you can easily tell if the LEDs are dead. Unfortunately due to the proprietary wavelength there are (at the time of this writing) no known good replacements. I do hope to change that eventually once I have some time to test various LEDs on the market and compare their output against the baseline I pulled from the original LED module. Until that happens your only real recourse is to simply replace the whole module. Thankfully replacing only one or two is generally inexpensive.

If you’re wiring up your setup for the first time and some or all of your LEDs aren’t lighting up you’ll want to first verify that it wasn’t installed backwards. Given that the input and output connectors are pinned identical there’s no risk of backwards voltage damaging the board but it also means it’s easy to accidentally install backward. Indeed I’ve done this a few times by accident and it didn’t seem to damage the LED board (at least not after a short period).

LED Board Variations

There are a number of variations of these LED boards, they all seem to be cross-compatible with each other and with any Gun Sense board, you can even mix and match them in the same chain. Though, depending on your cabinet some will work better than others in terms of gun range.

The original 2-LED module used on Jurassic Park The Lost World. Notice that the LEDs are arranged vertically and there is a glob of silicone placed below them to hold them in place. These actually work well with larger screens as you can move and adjust the LED angle to your liking.
The newer 2-LED module. Note the horizontal arrangement of the LEDs and the small plastic shroud. These were first used on House of the Dead 2 and continued to be used for most Sega IR Light Gun games through NAOMI, Hikaru, Chihiro, and Lindbergh (maybe further). These are going to be the most common LED board you come across.
This is an LED module from Namco’s Time Crisis 4, it’s nearly identical to the 2 LED Sega Model above. The most notable difference is PCB sizing is slightly different.

This is a 3rd Party Reproduction LED board that I’ve seen pop up in Europe. I find it intriguing that it has provisions for up to 6 LEDs though I’ve heard nothing but complaints about this PCB with guns having difficulty tracking them. Perhaps the wavelength is incorrect?
This is a 4-LED module, I’ve seen the part number referenced in the manual for Ghost Squad, however photos of actual machines show a normal 2-LED module. Having spoken to a former Sega Employee on the subject these modules were a special creation for custom large-screen installations where long-range was needed. Supposedly they made enough of them that most of them were sold as replacement modules along-side the normal 2-LED versions.

These are newer models used on Taito/Square Enix GunSlinger Stratos cabinets. Note the lack of any through-hole components. I also appreciate that each LED appears to be uniquely driven by it’s own transistor, where as on older LED boards they are typically wired in series.

There may be other LED modules in the wild but those above are the ones I know of, If you have photos of others please contact me and I will add them.

To Be Continued…
In Part 3 I will cover the IR Sensors

Everything you’d want to know about Sega Type II IR Light Guns. Part 1: Overview

In 1997 Sega released Jurassic Park The Lost World Arcade; a Light Gun Shooter on the Model 3 Arcade hardware. This was the first game to use Sega’s new IR gun technology, a system that they’ve used for nearly every light gun game they’ve produced since.

Continue reading ‘Everything you’d want to know about Sega Type II IR Light Guns. Part 1: Overview’

A Better Vewlix Power Supply

My Work-In-Progress Vewlix F

Recently I’ve been fixing up a Taito Vewlix F cabinet, this cabinet has the optional “JAMMA Kit” which includes the incredibly crappy Wei-Ya P271 Power Supply. This Power supply is notorious for pulsing the 12V line and killing itself (and potentially PCBs) when run on 120V AC.

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Light Output on Hyper Bishi Bashi Champ for Konami System 573

Last week I posted an article on getting light output from Salary Man Champ on Konami System 573, I suggest you read that first. Much to my chagrin the shift-register circuit I used there didn’t work with Hyper Bishi Bashi Champ. Through pictures I found online it seems that the 2 Player Hyper Bishi Bashi champ cart, while using the same light output pinout and having the same outward appearance and a very similar looking cartridge PCB actually used a very different light output circuit. Rather than a pair of shift-Registers it uses a pair of 74LS175 D-Type Flip Flops.

Here are some photos of the HBBC 2P cart (courtesy of nem on Arcade-Projects.com)

Continue reading ‘Light Output on Hyper Bishi Bashi Champ for Konami System 573’

Light output for Salary Man Champ on Konami System 573

I’ve been playing around with a non-rhythm game version of the Konami System 573 hardware, namely I’m interested in the various “Champ” games, these are collections of manic versus mini-games where you smack buttons and hilarity ensues.  The most popular is Hyper Bishi Bashi Champ and Salary Man Champ. If you’re unfamiliar with the game each player has just 3 colored buttons (no joystick) and the buttons also light up corresponding to what’s happening in game.

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ROMIDENT Drag and Drop Tool

What is ROMIDENT and why should you care?

When troubleshooting an an arcade PCB it can sometimes be helpful to compare the ROM data on your PCB to the ROM data within MAME. MAME is more than just a way to play classic games, the documentation within the source code is invaluable to understanding how the hardware works, and the ROMs themselves can serve as a tool to compare and verify the ROMs on your original arcade hardware.

To this end MAME has a great feature called “romident”. You’ll first need to use a EPROM reader/writer to read the data off of you EPROM or mask ROM and save it to a file, then you can check to see if that file exists in MAME by running this command: Continue reading ‘ROMIDENT Drag and Drop Tool’

Sega ST-V “Titan” Metal Cage (Atlus Print Club 2 PCB)

I’m a big fan of metal cages over my Arcade PCBs. They’re the best way to protect the PCB and they help cut down on electrical interference so the game runs at it’s best. I own an ST-V (“Sega Titan-Video”) PCB (which is the arcade equivalent to a Sega Saturn) and I knew it had an optional Video board used in the “Print Club” machines. While trying to find info on that optional board I discovered that in the Print Club machines also had a cage around the whole ST-V Board setup! I found a complete setup for a reasonable price (less than that of a spare ST-V board alone, so worst case I break even) so I bought it.

A number of people have expressed interest in the size of this cage and others in seeing what the guts of this thing looks like so here’s a quick photo dump.

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Dreamcast USB-GDROM tray Heat Test

I’ve heard a lot of people talking about Dreamcast cooling related to the GDEMU and USB GD-ROM devices. People claiming that by removing the GD-ROM drive the fan is unable to pull cool air across the power supply and other internal components and instead just pulls air through the large opening where the GD-ROM used to be; causing the console to run overall hotter than it did before. A lot of people have asked me if my GDEMU Tray or my USB-GDROM Tray helps with cooling. Without a good answer I decided to test.

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Building an Emulation PC for an Arcade Machine

If you have or want to build an arcade machine that displays and plays emulated games as authentically as possible then there are a number of things to consider that are quite different when compared to building a normal gaming PC. This guide assumes that you have a functioning arcade machine already and that you’re simply looking to install a PC in it to use along side your arcade PCBs.


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Tour of my Game Room 2016

I’ve done a brief video tour of my Game Room for those that are interested.

If you want to know what it looked like before I got back into arcades, or a more detailed look at some of the Collectors edition console games on the shelves I have a similar video from 2012