The Sega/Gremlin X-Y FAQ

========================
The Sega/Gremlin X-Y FAQ

version 1.12

written by: Mark Jenison
========================

1. Introduction
2. The X-Y Convert-a-Game system
a. The System
1. CPU boards
2. X-Y timing and control boards
3. Sound boards
4. EPROM boards
b. Monitor: Electrohome G08 X-Y
c. Power supply
3. Games
a. Space Fury
b. Star Trek
c. Eliminator
1. Upright
2. Cocktail
3. 4-player
d. Tac/Scan
e. Zektor
4. Repair tips
a. CPU
b. EPROM
c. X-Y boards
d. Sound boards
e. Controls
f. General Tips
g. Power supply
h. Monitor
5. Conversions
a. Game-to-Game
b. Related documents
6. Contributors
7. Document History

***************
1. Introduction
***************

This document discusses the Sega/Gremlin X-Y Convert-a-Games system.
These games were color X-Y games released in the early 1980's. The
Convert-a-Game system was designed so an operator could convert from one game
to another by simply changing artwork, control panels, game cages (and possibly
the orientation of the monitor) without having to re-wire the cabinet. All of
this could be done from the front of the cabinet.

The following were included in the series of Sega color X-Y Convert-a-Games
(listed in order of release):

- Eliminator
- Space Fury
- Zektor
- Tac/Scan
- Star Trek

*******************************************
2. The Sega color X-Y Convert-a-Game System
*******************************************

==========
The System
==========

This is just a brief overview. The system is explained in much more detail in
the Star Trek manual.

Each Sega color X-Y Convert-a-Game system consisted of what is known as the
G-80 system. It contains the following elements:

* CPU board
* Sound board(s)
* X-Y timing and control boards
* 48K EPROM board

These boards are about the size of a piece of paper (approximately 8 1/2"x11")
with one narrow end having a 86 (2x43) edge pins. All these boards fit into a
card cage, with the individual boards plugging into a interconnect board at
the bottom of the cage. The interconnect board allows the boards to be
plugged into the slots in any order or position. This board is supplied with
voltage from the power supply, and is how all boards are powered. It also
acts as a bus to get information between cards.

----------
CPU boards
----------

The CPU board itself is generic between the X-Y games. However, each game had
a special chip (protection chip/slapstick) at U21 and an EPROM at U25 that was
specific for that game (the only exception here may be Space Fury and
Eliminator). Some games have the same special chip as other games.

These are a list of which special chips go with which games:

Special chip (U21) EPROM (U25) Game
---------------------------------------------------------------------
315-0076 1390 Eliminator 4-player
1711 Tac/Scan
315-0064 969 Space Fury
1873 Star Trek
315-0063 959 Space Odyssey (version 1 & 2) (non X-Y)
315-0070 969 Eliminator
969 Eliminator cocktail
1346 005 (non X-Y)
315-0062 829 Astro Blaster (non X-Y)
315-0082 1778 Monster Bash (non X-Y)
1611 Zektor

If anyone sees any discrepancies, or can fill in some more the above data,
please send e-mail to: [email protected]

-----------------------------
X-Y timing and control boards
-----------------------------

These boards, often referred to as the X-Y pair, are the boards that control
the monitor. They are generic between all X-Y games. These boards are hooked
together via ribbon cable.

------------
Sound boards
------------

There is some compatibility of sound boards between games. There may or may
not be necessary EPROM swaps on some of these boards.

Sound board Games used with
---------------------------------------
Speech board Space Fury
Star Trek
Zektor
Battle Star/Space Fury Space Fury
Meatball/Eliminator Eliminator
Eliminator 4-player
Zektor
Universal Tac/Scan
Star Trek

Meatball and Eliminator sound boards are apparently the same. Sega changed
the name of this sound board during production of the game for some reason.
Zektor`s sound board (800-3249) is the same as Eliminators (800-3174) except
for these minor differences:

Ref Des ELIMINATOR ZEKTOR
R5 10K 4.7K
R9 33K 12K
R71 270K 100K
R79 2 MEG unused
R122 220K 390K
R132 220K 100K
C9 0.01uF 0.0047uF
C46 0.022uF 0.047uF

Also, there is a large socket on the Eliminator sound board which is supposed
to be populated with a SOUND AY-3-8912 chip. This chip must be present to
hear all of the sounds for Zektor. Without it, Zektor will be missing these
four sounds: ping, rotating rings, city flyby, and zizzers. Eliminator,
however, does not make use of this chip, so Eliminator will sound just fine
without this socket populated. The Battlestar sound board doesn't need this
chip either in order to play all of the Space Fury sounds.

Speech boards have very little circuitry on them, so don't get worried if you
pickup a set and see that the speech board is barely populated. I have seen
several speech board sets whose EPROM numbers are not continuous. For
example, Space Fury's speech board has EPROMs 970-972, and 808. The 808 is a
2716, while the others are 2732s. I would speculate that the 808's were from
Astro Blaster. However, these leftover EPROMS ARE NECESSARY for the speech
boards to run correctly. Star Trek uses a Zektor EPROM for its speech board.

------------
EPROM boards
------------

The EPROM boards are generic between games; any set of Sega/Gremlin X-Y EPROMs
can be put into any G-80 EPROM board.

============================
Monitor: Electrohome G08 X-Y
============================

The Sega X-Y Convert-a-Games came with the infamous Electrohome G08 X-Y
monitor. This monitor is infamous for its unreliability, and are probably
the main reason why these games were junked by operators so quickly. It is
commonly joked about on the net that if you operate one of these monitors, you
should also be the owner of a fire extinguisher (and keep it handy).

There were several versions of the GO8:

G08-001 - Original
G08-003 - The version Star Trek's came with. Documentation for this monitor
can be found in Star Trek manuals.
G08-004 - Found in some cocktails
G08-005 - Found in Cosmic Chasms

============
Power supply
============

The power supply that came with the Sega X-Y games provided an audio amp and
the following necessary voltages: +5VDC, -5VDC, +12VDC (for sound), -12VDC
(for video), and 3VAC.

According to John Robertson, "the original use of the 3VAC was a valid power
detect reset. If the power switch was quickly cycled on/off/on this would
force a reset. [This] Was a way around the fast cycle reset free credits that
some games gave."

********
3. Games
********

The following list of games are known produced Sega Gremlin X-Y games.

I have a flyer which promotes Sega X-Y Convert-a-Games that shows another X-Y
game called Battle Star. It appears from the screen shots on the flyer that it
is NOT a prototype game for Eliminator or Space Fury (the flyer shows a
Space Fury being converted to a Battle Star). Even though Space Fury has a
Battle star sound board, it is possible Battle Star itself was never released.

The Battle Star game that appears in the flyer is playing an unfinished game
called "Space Disc Launcher, according to Tom Haagen.

Most games came in the common Sega Convert-a-cabinet, which was used as the
cabinet for many of Sega's games (Congo Bongo, Zaxxon, etc). Any game where
"dedicated" cabinet is mentioned means that it also came in a cabinet other
than the Convert-a-cabinet.

==========
Space Fury
==========

Space Fury came in both upright and dedicated cocktail. Space Fury is somewhat
similar in game play to Asteroids or Space Duel. Enemies objects fly onto the
screen, "assembling" themselves into floating objects. The characteristic of
the objects depend on how many of the pieces are allowed to assemble. Between
waves, you are allowed to add an "attachment" on your ship, giving you
additional fire power, possibly in additional directions.

This game is probably most famous for it's one-eyed alien which taunts you
throughout the game. "So, a creature for my amusement. Prepare for battle!"

1 - Speech board (EPROM 970-972, 808)
2 - CPU board (EPROM 969, special chip 315-0064)
3 - X-Y timing board
4 - X-Y control board
5 - Sound board "Battle star" or "Space Fury"
6 - EPROM board (EPROM numbers 960-968)

Controls consisted of 6 buttons: left, right, thrust, fire, 1P, 2P.

=========
Star Trek
=========

Star Trek came in an upright Convert-a-cabinet, dedicated cockpit version,
dedicated upright, and was also available as a Sega X-Y Convert-a-Game kit,
which was popular for Asteroids cabinets. There is a switch setting for two
sets of controls, so it may be possible to play out of a cocktail, but I've
never seen one.

If you have a Star Trek board cage which has an edge connector instead of the
mate-n-lock harness, that means you have a Star Trek Kit cage. A mapping
finger board was supplied for game conversion (instead of the kit containing a
harness with about 6 miscellanous mate-n-lock connectors like the real
converta-cabinet has).

Star Trek was a popular Asteroids conversion. Replace the vector monitor and
insert a finger board and re-wire the control panel, and most of the existing
Asteroids harness could be re-used. However, the edge card connection pinouts
for Star Trek kits doesn't match any game (as far as I can tell), so a
mapping finger board was required for the Star Trek conversion kits.

If you have a Star Trek cage where the harness goes right to mate-n-lock
connectors that are mounted on the cage itself, then you've got one out of
a Star Trek cockpit.

The screen consists of 3 sections: 1) a display for score, available shields,
photons, and warp time, 2) a radar view of your ship, surrounding enemies and
star bases, and 3) a cockpit view from your ship; sort of like Battlezone in
outer space. The object of the game is to defeat the enemies in the sector.
There are star bases which you can dock with to get more shields, photons, and
warp time. There are bonus rounds which you must survive where NOMAD places
mines, and you must successfully navigate through the mine field them and
attempt to destroy NOMAD.

Of all games manuals, Star Trek's manual is probably the most helpful when it
comes to explaining the Sega X-Y G-80 system. It also has a good deal of
monitor information, and explains the theory of the G-80 system in detail.
Of all the Sega X-Y manuals, try to get a copy of this one.

1 - CPU board (EPROM 1873, chip 315-0064)
2 - X-Y timing board
3 - X-Y control board
4 - Sound board "Universal"
5 - Speech board (EPROM 1871-1872, 1607)
6 - EPROM board (EPROM numbers 1848-1870)

Controls consisted of an encoder wheel, thrust, fire, photon, warp, 1P,
and 2P (unless it was a sitdown).

==========
Eliminator
==========

There are three different forms of Eliminator, but the premise is the same:

There is a large spherical rock known as the Eliminator. It floats around the
screen and sends out ships to destroy you. You attempt to destroy enemy ships
by forcing them into the Eliminator with your energy bolts. The Eliminator
can only be destroyed by firing a shot down a narrow tunnel to its core.
I believe the Eliminator was coined as "The Death Bagel" by John Grigsby.

Although the games between the three different types are the same, different
versions, thus different EPROMs, were necessary to handle the displaying of
scores for each of the different cabinets. The attract modes for each game
stayed the same as the upright version, which is kind of odd for the 4-player
version since the attract mode implies only two players.

-------
Upright
-------

Eliminator upright came in the standard Convert-a-cabinet.

The Eliminator upright board configuration is described here. It consists of:

1 - CPU board (EPROM 969, chip 315-0070)
2 - X-Y timing board
3 - X-Y control board
4 - Sound board "Meatball" or "Eliminator"
5 - EPROM board (EPROM numbers 1333-1345)

Controls consisted of 10 buttons: left1, right1, thrust1, fire1, left2, right2,
thrust2, fire2, 1P, 2P

--------
Cocktail
--------

The Eliminator cocktail is very different in hardware than it's upright or
4-player counterpart. For starters, the game has a different power supply
configuration. It has what appears to be a basic switching power supply for
the +5VDC, a transformer, and a small board which looks to rectify some of the
other voltages, and also a small audio amplification board.

Also, the monitor in the cocktail has a different chassis than the ones used
in the uprights and 4-player model. The chassis is more compact, even though
all the parts appears to be the same (they are just mounted more closely to
the tube neck.)

The Eliminator cocktail board configuration is described here. It consists of:

1 - CPU board (EPROM 969, chip 315-0070)
2 - X-Y timing board
3 - X-Y control board
4 - Sound board "Meatball" or "Eliminator"
5 - EPROM board (EPROM numbers 1200-1212)

Two control panels containing left, right, thrust, fire, with the 1P, 2P
buttons on the cabinet.

--------
4-player
--------

The four-player version of Eliminator is a tall table top game where you stand
at each side of the monitor at a player control panel. It was not really a
Convert-a-Game per se, since no other games could be played out of its
cabinet and the game couldn't be played out of any other Sega/Gremlin cabinet
(without some serious hacking).

The four-player consists of basically the same set up of the regular upright
except that it has an external I/O board to handle all the additional coin and
control inputs.

1 - CPU board (EPROM 1390, chip 315-0076)
2 - X-Y timing board
3 - X-Y control board
4 - Sound board "Meatball" or "Eliminator"
5 - EPROM board (EPROM numbers 1347-1360)

Controls consisted of 4 control panels, each with: left, right, thrust, fire

No player start buttons were needed. There was a coin door for each side of
the cabinet under each player's controls. The coin mechs have lockout coils,
so as soon as a player put a coin in, the coin door would lock out attempts to
coin up that side again, and the player would use that side. A countdown from
10 would begin, and other players could coin in before it reached 0. Once it
reached zero, players could not join, and any remaining attempts to coin in
would be locked out. The players then try to "eliminate" each other. The
last remaining player must then face the Eliminator (and its drones) alone.

There are two versions of the Eliminator 4-player flyers. One shows a cabinet
where the control panel color indicates which color ship the player controls.
There is also a typo in the description of play text. This flyer also shows a
"high impact promotional canopy" (which is optional) on the back.

There is also another version of the flyer which shows each of the control
panels being black, with only the color of the buttons and a number to
indicate which control panel controls which color ship. It also lacks the
promotional canopy on the back of the flyer, and the game description text does
not have the typo on it.

The only 4-player Eliminators that I've seen have each of the four control
panels the same color as the players ship.

========
Tac/Scan
========

Tac/Scan was a kit for the Convert-a-cabinet, and also came in a cocktail
according to the flyer.

You pilot a fleet of seven ships which all move and fire in unison.

First scenario: Shoot down enemies while you pilot your fleet through waves
of descending enemies. The game play for this scenario is unique; your
ships are at the bottom of the screen, firing up, but you can rotate the ships
to fire left and right, and pilot your fleet past enemies. The formation of
your ships also changes. Additional ships appear occasionally which you can
catch and add to your fleet.

Second scenario: Basically the same thing, except in a 3-D perspective from
behind your fleet. Additional ships are also awarded here.

Third scenario: Pilot your fleet down a warp tunnel. Avoid hitting the sides
or you will lose ships.

1 - CPU board (EPROM 1711, chip 315-0076)
2 - X-Y timing board
3 - X-Y control board
4 - Sound board "Universal"
5 - EPROM board (EPROM numbers 1670-1688, 1709-1710)

Controls consisted of: encoder wheel, fire, add ship, 1P, 2P.

======
Zektor
======

This is the rarest of the Sega XY games. The game was basically "lost" until
April of 1997, when Paul Frazee discovered a partial boardset and posted it for
sale (not knowing the attention that this one boardset would draw). He then
held an auction for the partial boardset, and it was purchased by me (and a few
other unnamed contributors - thanks guys) for $400! Turns out I had found the
CPU EPROM chip in a warehouse raid about a year prior to the auction, which
made the boardset complete. In early January of 1998, Lee Bender found a
complete Zektor cabinet.

"Dangerous Dann" Frank <[email protected]> contributed this description of
Zektor, taken from the manual, flyer, and his personal experience with the
game.

-------
Object: To "recapture Eight cosmic cities that have been seized by an evil
cadre of alien Robots." Each city is named in an Alphabetical progression
(and increasing difficulty) in this order...

Ascella
Baitos
Centaurus
Denebala
Eridonus
Faltar
Graffas
..???

Each city's liberation begins with a different "Robot" image and
voice confronting the player... The robot ruling "Faltar" was a male with a
deep voice stating "I rule Faltar now, you will have to fight for it".
There are also female robots such as the one who declares "I have conquered
Eridonus. You will not take it from me"

To liberate each city, the player must defeat three 'waves' of enemy
FIGHTERS' and ROBOPROBES that are often 'shielded' (in red) and who fire
lethal zig-zag shaped 'Zizzers' at the player's ship. Also there are three
types of MOBOIDS, and their features are as follows...

Green Moboids... 'Spin' player's ship on contact and 'bounce' enemy ships
Blue Moboids... 'Bounce' all ships
Red Moboids... Destroy all 'unshielded' ships (including Player's ship)

After defeating the three waves of attack, the alien Robot holding
the city appears within three concentric rings (a la "Star Castle") through
which a 'Slot shot' can be scored 'neutralizing' the Robot and earning the
player a Bonus ship. If you don't make the shot after a period of time, you
still advance to the next level, but don't get a bonus ship.

Enemies who are shielded must be hit several times to weaken the shields
before they are destroyed.

The last boss is the alien from Space Fury.

The game board consists of:

1 - CPU board (EPROM 1611, chip 315-0082)
2 - X-Y timing board
3 - X-Y control board
4 - Sound board - "Meatball" or "Eliminator" (modified as mentioned above)
5 - Speech board (EPROM numbers 1607-1610)
6 - EPROM board (EPROM numbers 1586-1606)

Controls consisted of: encoder wheel, 1P, 2P, thrust, fire

**************
4. Repair Tips
**************

So you have a set of what you believe to be a complete Sega/Gremlin X-Y game.
You have your working monitor and a good power supply. You power up the game,
hoping to see the games attract mode come up on the screen, but instead you
get a garbled mess of graphics, a still picture, or no picture at all.

Welcome to the wonderful world of Sega/Gremlin X-Y games.

Well, don't fret. These marvels of technology were designed to be modular so
that they could be debugged easily. It helps to have a known *working* set to
swap parts around to figure it where the problem lies, but if you aren't so
fortunate, here's some debugging advice.

==========
CPU boards
==========

The led on a good CPU board will flash out information that can be used to
debug other problems; check the manual for these codes.

If the game isn't coming up, press the test plunger. If you get a halt light,
try replacing the 2114 RAMs and replacing the Z80 CPU and see if that fixes it.
If the halt light flashes repeatedly, the first 1k of EPROMs is either bad or
making a bad connection.

By the way, bad sound boards and speech boards can cause symptoms that might
make you suspect the CPU or X-Y boards are bad. Do not test CPU and
X-Y boards with untested sound and speech boards. You don't need these boards
in the card cage for the game to run, so unplug them and set them
aside until you've tested the rest of the boards.

============
EPROM boards
============

First things first; reseat each EPROM on the EPROM board and check all pins
are getting a good connection. It doesn't help to try and debug a program
that cannot run. I've seen many different versions of sockets used on these
EPROM boards, and in most cases if the EPROM board doesn't seem to be working,
it's because of the sockets. There are three or four devices on the board
itself, so replacing them all wouldn't be a problem if it came down to that.

==========
X-Y boards
==========

Listen carefully to your monitor when you are working with these boards. If
you power up and you here the deflection circuitry working (what is known as
"deflection chatter"), then it's likely the control board is bad, and your
timing board is probably ok. If you hear nothing, it could be either board.

Press the test plunger on the CPU and it should flash out the location of
any bad 2114 RAMs on the timing board. Keep doing this until all bad 2114
RAMs have been located and replaced. B.G. Micro, Inc (1-800-276-2206) is a
cheap source of 2114 RAM chips.

I get a lot of cases where people aren't sure if they have the video
connectors on correctly. The "wiring diagram" on the boardset or in the
cabinet can confuse the issues, so just ignore it and follow the guides
below for hooking up the video.

This guide assumes that the boardset is in it's normal position,
where the power plug is on the right and you are looking into the cage.

XY-control board (controls RGB; "remember...COntrol means COlor")
This is the board of the XY pair which has the highest connector
of the two.

Numbered counting down from the top. This connector normally has
3 different color wires.

1 ----- Green
2 Empty
3 ----- Red
4 ----- Blue

XY-timing board (controls the XY position)
This is the board of the XY pair which has the lowest connector
of the two.

Numbered counting down from the top. This connector normally has
2 wires of the same color, and a bare wire for the Shield wire.

1 ----- Y
2 ----- Shield
3 Empty
4 ----- X

Hopefully this makes things more clear. Remember, for the top connector,
pin 2 from the top should be empty, and for the bottom connector, pin 2
from the BOTTOM should be empty.

============
Sound boards
============

On sound boards, the ground (shield) is the bottom pin, and the upper pin is
the sound. Be especially careful when hooking up the speech boards, as in
some instances, the first pin is cut off, causing you to connect audio out
directly to ground; not good.

Each game has a sound test. This test can be deceiving. The loss
of sound(s) does not necessarily mean the sound board is bad. A bad CPU board,
bad speech board, bad amplifier, or screwing up the connectors will also cause
a loss of sounds. Sound problems are the least simple to debug. A common
problem with these boards is that most sounds will work, but some will be
missing. The Star Trek manual mentions the exact circuits to look at for it's
sounds, which is nice if you have a bad Universal sound board. For the Space
Fury sound board, usually a sound failure is due to a 4.7uf capacitor in the
sound's circuit going bad. Replace these first. If that's not it, have a few
spare TL082 op-amps handy. The same with the Eliminator sound board.

Maybe your set works, but is missing speech. Fortunately, this board has a lot
of socketed devices (this board always appears to be missing a lot of devices,
but it's not). David Shuman suggests: "...try replacing the socketed
TL082 op-amp on the speech board. This swap brought back the speech on one of
my Space Fury sets. The other problem chip is the 8035 CPU-- this is another
part that, when it dies, knocks out the speech. Both the TL082 and 8035 are
available cheap from B.G. Micro.". Speech boards can be nasty, as bad ones
can create symptoms like multiplier errors and no sound at all, which might
make you think the sound board is bad.

Universal Sounds board are a major pain to debug. The Star Trek manual
specifies which circuits control which specific sounds, so get a copy.
I don't remember if the Tac/Scan manual does the same.

Is your Sega XY game too loud, and you can't turn it down low enough? Check
right behind the volume pot. There should be a resistor, maybe under some
shrink wrap, that will be inline with one of the inputs to the pot. Changing
the resistor to a lower value (or removing it altogether) will allow you to
reduce the volume of your game to bearable levels.

========
Controls
========

The control that causes the most problems is the spinner. If your ship is
spinning erratically in Star Trek, or the numbers are changing drastically
during test mode, there is a problem. I'd say ninety percent of the time
the problem is caused by loose connections somewhere along the line, typically
in the Mat-n-lock connector. The female pins tend to lose tension and open
up, so use a small flathead screwdriver and push them closed again so they
make a tight connection.

============
General Tips
============

Double check your connections; these games have a bunch of connectors that are
not keyed, so it is easy to put one on backwards by mistake (making it
especially easy to fry sound and video boards).

The self test is useful, but not flawless, however. All self tests may pass,
but you could STILL have a screwed up game. The only thing I could suggest is
the EPROMs, since the self test only tests a certain portion of the EPROMs,
not all EPROM data. I have an Eliminator 4-player that originally passed the
EPROM test, but the player 2 and 4 ships were still screwed up. The problem
turned out to be a corroded socket where an EPROM was not making a good
connection.

============
Power supply
============

Sega/Gremlin power supplies are not the most reliable. If you have a dead one,
you have a few choices: you can repair it, or replace it.

In most cases repairing these power supplies is straight forward. If you open
it up, you'll see there's really not much to it. The voltage regulators are
all mounted to the heat sink and can be easily replaced. If you are missing
a voltage, the schematics for the power supply are very straight forward, and
it usually means simply replacing the voltage regulator in that circuit. I
also recommend replacing the connector and connector pins for any burnt
connectors, and resoldering the header pins on the power supply PCB.

If you decide to modernize your game and put in a switching power supply, there
are a few things to consider:

1) The Sega/Gremlin power supply has a built in audio amplifier. You'll need
to provide your own if you replace it. I've had good luck with using the
Bally Midway Dual audio amps as a replacement, but any audio amp should do.
2) You'll need a 3VAC supply for the power-on reset. I've heard that using
+5VDC as a substitution may work, but your milliage may vary.
3) You'll need +5VDC, -5VDC, +12VDC, and -12VDC. John Robertson says you
may be able to get by with substituting -5VDC for the -12VDC for the video,
but you'll need to adjust your picture.

Or if you wish, you can use a switching power to supply the more common
voltages and keep the old power supply in there and use it for the things that
may still work (audio amp, 3VAC, -12VDC). Just make sure if you do this to
make the grounds common between the two power supplies.

=======
Monitor
=======

Instead of making this section as huge as it could be (or should be), I'm going
to try and make it brief and just describe where the problem likely lies. The
following tips are assuming the power supply and game boards are known to be
good.

First off, always start by resoldering all the vertical header pins on the
deflection and high voltage PCBs. Second, pull the connectors for the heat
sink mounted deflection transistors, and test them through the connectors.

From David Shuman - "The original parts on the G08-003 are 2N6259's,
which don't seem to exist anymore. I asked around on sci.electronics and
people recommended the following substitutes: ECG388, 2N5631, MJ15003,
SK3947. I haven't tried any of these swaps, so do so at your own risk.
I'm told that the ECG and SK parts won't perform as well under heavy
stress (like in a G08), so you might want to try the other two... I know
MCM Electronics carries the MJ15003 (which, incidentally, was the part
used in the original G08-001)."

Symptoms: No heater glow

The HV is gone. Check the HV unit. The heater filament runs off a winding
on the HV transformer, so if there's no glow, it's a good bet there's no 22.5kV
either.

The pinouts for the HV unit:

1 - Y
2 - X
3 - -9.1VDC
4 - +9.1VDC
5 - GND
6 - GND (heater)
7 - +6.3VAC (heater)
8 - +126VDC
9 - NC
10 - VG2 (variable gain; part of brightness circuitry)

Be careful not to short the pins together when measuring voltages!

The monitor has a unique spot killer system, in that if it receives no valid
inputs, it will shut down the high voltage. So your monitor may be fine
and it may be your X-Y boards which are causing the lack of high voltage.

Let me just say this; in general, the entire system set up (monitor, power
supply, board sets) is flakey. The monitor has been redesigned several times,
the power supply has surface wire hacks and cut traces, and the board sets
aren't very reliable. If you get a working set up and running, hold onto it
like gold, but prepare parts in advance for any problems that may transpire.

Good luck!

**************
5. Conversions
**************

============
Game-to-Game
============

So you have a Sega/Gremlin X-Y game, and have been looking to add to your
collection of Sega/Gremlin X-Y games. However, these games in general are
hard to come by, and if you *do* find another, it is likely it won't be
working. Well, if you can gather just a FEW pieces, you may be able to
convert your game "X" to game "Y".

In order to convert game "X" to game "Y", the *minimum* you would need
would be:

1) Game "X"; a working game "X" would be best, but it's possible that the
parts you swap in for "Y" will get you a working set.

2) The audio board for the game. Space Fury, Star Trek and Zektor
would need the additional speech board as well.

3) A copy of game "Y"'s EPROMs. This includes the CPU EPROM U25 for game "Y",
and maybe speech board EPROMS as well.

4) The special protection chip at location U21 for game "Y". This will be the
hardest to come by. If you are lucky, your game "X" will already have this.

5) Controls. Star Trek control panel could run Tac/Scan, Eliminator (2 player)
can run Space Fury, etc.

For example: To add Space Fury to your Star Trek (assuming it's in a Sega
Convert-a-cabinet), you'd need the EPROM data, Battle Star sound board, and a
spare control panel; a control panel from just about any Convert-a-Game
(Zaxxon, Congo Bongo, Eliminator) will do. Swap EPROMs on the EPROM board,
speech board and CPU board, swap in the sound board and swap control panels
(assuming you've modified it for Space Fury) and your done!

Probably a lot of the EPROM swapping could even be avoided if someone figured
out how to strap the game for a larger EPROM, and use some banking tricks so
that you'd only need to swap sound boards and control panels.

Rick Schieve wrote up an article talking about how he added 4-player Eliminator
to his Tac/Scan set up: http://ubd3.vdospk.com/nostalgia/text/elim.txt

David Fish figured out the security scheme used by Sega. He broke the code
and rewrote all the EPROM data to be non-security chip specific. Clay Cowgill
took this one step further and made a kit for Sega XY games so that all the
data for all five games fit on ONE EPROM, and made a daughter board kit so that
all five games could be played without switch special chips or EPROM data (only
sound boards need to be swapped).

=================
Related Documents
=================

1. Wells Garner to Sega X-Y hack -- David Shuman
http://www.spies.com/arcade/conversion/SegaToAtariXYConv

2. The Sega Vector Game Page -- Ian Boffin
http://www.gamearchive.com/video/manufacturer/sega-gremlin/vector/

3. The Sega Multigame Hack -- Clay Cowgill
http://www.multigame.com/sega_mul.html

4. The Electrohome G08 FAQ -- Mark Jenison
http://www.enteract.com/~jenison/mars/faq/G08.FAQ

***************
6. Contributors
***************

Mark Jenison <[email protected]>
David Shuman <[email protected]>
Rick Schieve <[email protected]>
Kevin Klopp <[email protected]>
John Grigsby <[email protected]>
Dangerous Dann <[email protected]>
Kerry Stillinger <[email protected]>
Dwaine Hurta <[email protected]>
Zonn Moore <[email protected]>
William La Covara <[email protected]>
John Robertson <[email protected]>
Ian Boffin <[email protected]>
Paul Tonizzo <[email protected]>
Al Kossow <[email protected]>
Clay Cowgill <[email protected]>
Tom Haagen <[email protected]>

*******************
7. Document History
*******************

Version 1.0: Initial Release
Version 1.1: Added information about Zektor
Version 1.2: Added more to Sound board section
Added information about Battlestar
Version 1.3: Added more speech board information
Version 1.4: Added Eliminator cocktail information
Version 1.5: More added to repair section
Version 1.6: Zektor section updated
Version 1.7: Updated sound board section - Zektor sounds figured out
Version 1.8: Zektor section updated
Conversion section updated
Added new Eliminator 4-player flyer information
Version 1.9: Corrected information about cocktails and monitors
Updated some links and some e-mail addresses
Version 1.10: Add more power supply tips
Version 1.11: Added Sound board and Controls repair tips sections
Version 1.12: Added guide for putting on connectors for XY-pair