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Galaga DIP switch settings:

Shown above are two banks of DIP switches on the Galaga CPU board. They are labeled 6K and 6J.
Below are the switch settings:

Error codes...

Pinouts...

¹ Ground this pin for cocktail mode 
² Extra pins for Gaplus/Galaga 3/Metro Cross/Namco Dig Dug, etc...

On the CPU board there is a 3-pin Moldex power connector. This is a secondary power feed along with the main harness. It's pinned as follows:

On the Video board, there is a 6-in Molex video out connector. It's pinned as follows:

Here is a pic of the sound section containing the MB3730 Sound AMP and volume adjustment dial.

Tips:

Logic board IC replacement (7400 series)

When replacing a defective IC, use only Texas Instruments type (Ti). If other manufacturers IC's are used it can cause timing problems.

A classic case of bad video ram on the video pcb. Bad video ram usually causes vertical lines in some or all of the graphics. Take a look at the pictures below, and this screen shot.

Bad RAM	Good RAM

Below is a picture of the eight 2147 (4K x 1) RAMs that could cause the above problem: Normally you would have to swap out one ram at a time until you find the culprit... Note: 2147 RAMS are in positions 6M, 6L, 6K, 6J, 6F, 6E, 6D and 6C. 

... Or you can remove the eight above rams and install two 2148s (1K x 4) in their place: Note: 2148 RAMs go in positions 6H and 6B.
Using two 2148s require that all 2147s be removed! 

If you have some of the following problems, a little "house cleaning" can get you going!

I took the boards out of my galaga last night. I reseated most of the socketed chips and cleaned the contacts on the chips and I reseated the edge connector. I put the boards back into the machine, and voila! all my problems disappeared. The machine is playing perfectly!

Just for reference purposes, the problems I had that got fixed:

1. The game would reset but I could not start a game (the one player and two-player buttons would not start a game).
2. I had horizontal bars appear over the explosion whenever a bee was killed.
3. All the characters on the game would start to phase out. Almost like a klingon bird of prey cloaking.
4. As the game warmed up, all the sprites would block out(the bees and ship would be one solid color).

Example of dirty & clean pins on a chip
Dirty pins	Cleaned pins

Note: We now offer replacment custom chips!

Installing a switching power supply

One item that will need replacing one day is the power supply. Finding parts to repair the old PS can be quite hard, so you will be better off installing a new switching PS.

Need to adjust the power supply:

Here is the easiest location to check the +5 vdc power. You must test the power on the logic board, not the power supply. Place the probes on the cap as shown above and adjust the +5 to at least +5.2 vdc. This procedure is the same reguardless if you have an original power supply or a new switcher.

Working with a Dead Board

When I first work on a non-functioning Galaga, I always first pull every socketed chip and clean the legs of the chip. I usually use a small brass brush the size of a toothbrush to clean the legs, but be very careful as the legs are often brittle and will break off at the smallest application of force to them. Some recommend using a pencil eraser for this, but I have never tried it. I also use gold-plating contact cleaner to spray the legs of the chips after I have cleaned them. Gold Guard and ProGold are common brands. Occasionally I will use a little contact cleaner and spray it into the socket itself. This tends to help the connection between the socket and the chip.

Another common point for failure is the ribbon cable between the two boards. Often this cable is loose or becomes loose while the board is being installed. I usually pull the cable off and clean the contacts with contact cleaner. If the cable is extremely loose, I will sometimes use a couple of dots of hot glue to secure the cable in place.

If your Galaga is booting up and then freezes on the "RAM OK" screen, check your power supply! Almost always there is a problem with the +5. Check the voltage at the chips and adjust the power supply until the voltage is 5.1 or so. A problem with the +5 can also cause the game to reset randomly during game play, although it usually happens when the game first boots up. Always check the voltages (at the chips) first, before going on to more advanced troubleshooting. I have also seen a bad Z80 cause this.

The card edge connect at the top of the board and the filter board can also develop loose or bad connections over time. I usually clean the edge connectors on both the filter board and the CPU board when I first start to work on a board. Occasionally a component on the filter board will fail and you will loose a signal, this is usually manifest as a lost color or sync on the monitor or the loss of some input such as the control panel buttons and may also cause a loss of sound altogether.

Problems with Gameplay

One of the more common problems I have seen with Galaga boards is a problem with the sprites (moving objects on the screen., i.e. the players ship, enemy bugs, etc.). Usually this looks as if each sprite is a block of moving vertical white lines. Every single instance of this problem I have seen has been a failure of some sort of the 04xx chip. Usually the chip is just loose because of a poor socket or the legs have become oxidized and are making poor contact.. Cleaning the pins of the chip or replacing the socket clears this up. Occasionally the chip itself fails, in this case you will need to locate a working replacement (see my discussion later on finding replacement chips).

I once had a board that had vertical "tearing" of the sprites. It looked as if every other row in the sprites was being dropped toward the bottom of the screen. I finally traced this problem to the power supply. The tearing would appear when the board was used with an original Midway linear power supply, but disappeared when used with a modern switching power supply.

If your board is re-booting at the grid screen, but occasionally makes it farther, check the 06xx at location 6L. (Can't really just check it, try swapping with a known good one).

Sound Problems:

The main audio output is amplified by an MB3730, this chip is becoming increasingly hard to find and expensive when you do find it. I recently spoke to Consolidated Electronics who were about to import a shipment of MB3730s from Asia, the price quoted to me was around $35 a chip. But don't fret!, you can cannibalize MB3730s from the Midway MCR II series games. These games, such as Tron, Spy Hunter, Two Tigers, etc. use a small sound amp board called the "Dual Amp Board". Each board has two MB3720s on them and they can fairly easily be had. I often cannibalize the Dual Amp board for Galaga amps.

If you are missing all but the explosion sounds, there are two BiPolar ROMs on the top (CPU) board that are part of the circuit that generate all the other sounds; chances are that one or both of these are bad. Another problem area is the two 7489 RAM chips in the same circuits go bad. You can also look for resistor packs in the same area that have leads detaching from them.

Only the 05xx and the 54xx chips are specific to Galaga,

Distorted sounds: Sound decoder prom at 1D , the 74273 at 3B and the CD4066 at 3A; failure of any or all of these can cause distortion or loss of sound.

James M.

Troubleshooting

Problem: All you get is a White screen problems...

Fix: Chip 1N (a 07xx custom chip) and/or 1H chip (04xx chip) both on the video board.

Fix: It can be any one of the 2L, 2J, 2H or 2E custom chips on the CPU board.

Problem: Boardset goes through opening self-test, but locks up at "RAM OK" message and stays there. Board ALWAYS does this at power-up. Replacing cheesy sockets, bad resistor networks, and all socketed chips does not do anything to change this.

Fix: The problem was on the CPU board. After isolating all of the easy stuff, I finally found that the problem was a corroded trace beneath a TTL chip! There is supposed to be a trace beneath the 74LS367 at 1K, connecting pins 1 and 15 together. You'll see it on the schematic as an activation signal that tells the buffers when to do their thing and let the address signals reach the bus. Well, with that trace open, only some of the buffers were being told to turn on. What's more, you couldn't physically see the break!!!! It was only dumb luck that I'd decided to test it with an ohmmeter. Soldering a jumper wire fixed the whole darn thing. Therefore, if anyone else should run across this type of problem, granted that it may not be a corroded trace. But a "RAM OK" problem could indicate a bad 74LS367 on the CPU board --- and there are plenty of them!!!!

Matt J. McCullar
Arlington, TX

Problem: Game goes into RAM & ROM test or locks up while playing...

1. Check for +5.2vdc voltage setting measuring across capacitor C1 at location P7 on the CPU board. 2a. Check for 4MHz Z80-A CPU at location 4M on the CPU board. 2b. At locations 4E & 4J, the CPU must be the 2.5 MHz Z80 or D708C type.

Some Galaga PCBs use the weird resistor pacs, that are some sort of flat ceramic package with leg/pins soldered/pressed on. These are very unreliable with time and if they are ever bent. In my particular situation the 2.2K ohm pack RM17 was iffy and as a result I would get the dreaded RAM XX bad. Swapping the RAMs was not the solution. I placed 8 individual 1/4 watt 2.2K Ohm resistors, tied together at the top & fed to pin one as my fix.

An example of this procedure:

Original	Retrofit

Kev

Hardware Info:

Galaga is overpopulated with unnamed custom chips, they are all the black chips identified only by four number. Here is a breakdown of the custom chips:

* 00xx Address multiplexer for fixed RAM between CPU and video clocks
* 02xx Custom shift register for data from graphics ROMs
* 04xx Motion object and scratch RAM to CPU bus interface
* 05xx Generates blinking star backgrounds
* 06xx Bus interface
* 07xx Clock divider counter array 
* 08xx Multiprocessor data bus interface
* 51xx Input I.C., Player/DIP-switch/etc.
* 54xx Generates "explosion" sounds

Galaga uses 3 Zilog Z80s. Two for gameplay, and one for sound. There is also a custom I/O chip that handles the joystick and buttons. There is a bootleg version of Galaga that has 4 Z80's. The extra one emulates the custom I/O chip!

Other trivia: it uses the same sound hardware as Pac Man, Ms. Pac Man, Dig Dug, and Xevious. Dig Dug and Xevious also have 3 Z80s, used in a manner very similar to Galaga.

The sound hardware has 3 independent channels for playing music and sound effects. The explosion sound is not in the sound chip... it's another circuit.

The graphics hardware consists of a starry background behind 64 sprites, behind the top layer of characters (for score and messages).

Galaga is a multi processor architecture machine. The processor board is a subset of the Bosconian processor board. In fact a bosconian CPU will run the Galaga code. A galaga video board is required though.

Processor 1 ----------- Z80A, clocked at 1H. Board position 4M. Uses 4, 2732 eproms these are mapped at 0000-3FFF sequentially 3N(gg-a),3M(gg-b), 3L(gg-c),3K(gg-d). It uses a sync bus controller (08xx) at 2J to access common system areas. It uses IRQ1, and NMI1. The source of NMI1 appears to be the unknown device at 2L(06xx)

Processor 2 ----------- Z80, clocked at 1H, board position 4J. Uses 1 2732 eprom 3J(gg-e) mapped at 0000-0FFF. It uses a sync bus controller (08XX) at 2J to access common system areas. It uses IRQ2, and NMI2. The source of NMI2 is the 50 way edge connector to the video board, but the video board does not appear to use it.

Stack area 9100, accesses video bus D, and the A ram at least.

Processor 3 ----------- Z80, clocked at 1H, the horizontal dot clock frequency Board position 4E. Uses a single eprom (2732) at position 3E(gg-g). This is mapped at 0000-0FFF. It uses a Z80 sync bus conrtoller chip(08xx) at 2E to access common sytem areas. It uses NMI3 and IRQ3. The source of NMI3 is the clock generator IC(07xx) at 4D, but it is enabled by the !NMION signal.

It seems to access video ram in the video bus 'D'area. Stack area is 9B00

COMMON SYSTEM AREA ------------------ IC 2P,1P do most of the decoding on the cpu board.

2P   AA AAA    C11 111    K54 321    001 101   -> !I/O       i.e 6800-6FFF    001 110   -> enable 1P1P  EE+ RAA    NN5 W54    001 000   -> A6 PROM 5C, sound related  6800+    001 001   -> WE ram 2B(7489) , sound related.    001 010   -> select register 3C, system control                 bottom 3 address bits select which bit.    001 011   -> !WDR watchdog reset, must be held each vblank.    001 100   -> read dip switches. A 2 bit read, of 16 switches                 selected by bottom 3 address bits.ADDRESS SUMMARY---------------    AAAA AA   1111 11AA AAAA AAAA  R   5432 1098 7654 3210  W  +----+----+----+----+   0111 0xxx xxxx xxxx  X I/O -> IC 2L coin,control,background sound   0110 1xxx xx00 xxxx  W A6 prom5C    0110 1xxx xx01 xxxx  W 2B 7489 write   0110 1xxx xx10 x000  W d0 clr IRQ1   0110 1xxx xx10 x001  W d0 clr IRQ2   0110 1xxx xx10 x010  W !NMION   0110 1xxx xx10 x011  W !RESET   0110 1xxx xx10 x100  W MOD0 use unknowm   0110 1xxx xx10 x101  W MOD1 use unknown   0110 1xxx xx10 x111  W MOD2 use unknown   0110 1xxx xx11 xxxx  W !WDR watchdog reset.   0110 1xxx xx00 x000  R Dip sw read (d0=6k sw0,d1=6j sw0)   0110 1xxx xx00 x001  R Dip sw read (d0=6k sw1,d1=6j sw1)   0110 1xxx xx00 x010  R Dip sw read (d0=6k sw2,d1=6j sw2)   0110 1xxx xx00 x011  R Dip sw read (d0=6k sw3,d1=6j sw3)             0110 1xxx xx00 x100  R Dip sw read (d0=6k sw4,d1=6j sw4)   0110 1xxx xx00 x101  R Dip sw read (d0=6k sw5,d1=6j sw5)    0110 1xxx xx00 x110  R Dip sw read (d0=6k sw6,d1=6j sw6)   0110 1xxx xx00 x111  R Dip sw read (d0=6k sw7,d1=6j sw7)NOTE the IO circuitry contains 2 custom chips, one of which issuspected to be a custom z80 processor. No investigationat this point.VIDEO BOARD-----------IC 1E does most of the CPU related address decoding on the video board.  CAA AAA  K11 111   45 321  010 000  -> !RAM, IC 2K, RAM IC 1K, TMM2016 , 2K*8 bus "A"  010 001  -> IC2F, RAM 3F,3E, Data bus "D"  010 010  -> IC2J, RAM 3L,3K, Data bus "B"  010 011  -> IC2H, RAM 3J,3H, Data bus "C"  010 100  -> !port-> ic 5KIC 04xx decodes some other addresses maybe ? DECODE SUMMARY--------------  AAAA AA  1111 11AA AAAA AAAA  5432 1098 7654 3210  1000 0xxx xxxx xxxx 8000-87FF "A" RAM  1000 1-xx xxxx xxxx 8800-8BFF "D" RAM                      8C00 8FFF "D" RAM mirror  1001 0-xx xxxx xxxx 9000 93FF "B" RAM                      9400 97FF "B" RAM mirror  1001 1-xx xxxx xxxx 9800 9BFF "C" RAM                       9C00 9FFF "C" RAM mirror   1010 0xxx xxxx x000 A000 D0 sets IC5 bit0  1010 0xxx xxxx x001 A001 D0 sets IC5 bit1  1010 0xxx xxxx x010 A002 D0 sets IC5 bit2  1010 0xxx xxxx x011 A003 D0 sets IC5 bit3  1010 0xxx xxxx x100 A004 D0 sets IC5 bit4  1010 0xxx xxxx x101 A005 D0 sets IC5 bit5  1010 0xxx xxxx x110 A006 D0 sets IC5 bit6  1010 0xxx xxxx x111 A007 D0 sets FLIP    VIDEO ROM DECODING------------------ROM4L (gg-J) is USED by RAM "A" Suspect this is the character ROM

Galaga Cheats:

No fire cheat
	On either level 1 (or level 2 ?) let the last wave of "bees" get into formation on the screen without shooting them. Now, shoot everthing, BUT DO NOT SHOOT THE 2 BEES ON THE FAR LEFT OF THE SCREEN.
	Let these bees dive bomb over and over and over... Don't move your ship to the far side and walk away, they WILL drop a bomb that will reach the far side!
	After approx. 10 to 15 minutes, they'll stop dropping dombs. Let them dive by four or five times to be sure that they've stopped bombing. If so, now shoot them.....and voila!! NONE OF THE BUGS WILL DROP BOMBS FOR THE REST OF THE GAME!! This will work on games with the original ROM set only. If this doesn't work the board has the patched roms to prevent this "bug". This cheat was added by one of the programmers so he could beat the high score on any Galaga. Note: I've been told... "In a two player game, if player one stops the bees from firing and player one's game ends before player two, the bees START FIRING AGAIN for player two." - Dave B.

200% Hit-Miss Ratio
	Here is a neat Galaga trick: It is possible to end the game with a 200% hit/miss ratio. The 200% ratio trick can only be done with your first shot of the game. When the game starts, don't move, and fire only one shot. If you time it correctly, two enemies will be killed at once. Let your remaining ships be destroyed, and presto: a better-than-perfect result.

Game Tips: The "Player 1" score counter in Galaga is 6 digits, but the "Player 2" counter is seven digits. Therefore, most good players start a 2-player game and play exclusively on the Player 2 side so their score won't "roll over" at 999,990. Challenging stages are easier if the high score numbers are used to refine your aim. These tips assume a 6-digit high score: On the first 2 challenging stages, aim your ships so that your left set of bullets falls between the second and third numbers in the high score list. On subsequent challenging stages, aim one set of your bullets between the first and second numbers in the high score list (if the units come from the left) or between the last and next-to-last numbers (if the units come from the right). This will allow you to hit descending enemies at the highest possible point. If you have more than 7 extra men, the marker for the screen will only show 7 1/2 (!) men remaining. Additional extra men will still be credited, even though they won't show on the screen. Galaga "rolls over" after stage 255. After finishing the 255th level, the screen says "Stage 0" and the machine locks up. I have heard unconfirmed reports in the past that the "Stage 0" problem can be circumvented if the last two numbers in your score at the end of level 255 are (?? 80 is what I remember, but it may be something else). After the 1,000,000 mark, new ships are no longer awarded.

Stop the press! Here is an update to the above info! 

Scott B.

Board Sets (PCBs)...

Namco/Midway Galaga board set:

- Your Galaga board set should have two PCBs, a Midway CPU/Namco CPU & Video. All boards should be the same size!
- The CPU PCB will have a 3 pin power connector and 44 pin card edge connector.
- The video PCB will have a 6 pin video connector.

Namco Classics Volume 1 board:

- Namco classic Collection Volume 1 board contains Galaga, Xevious and Mappy with different arrangements of each game.

Galaga/Ms. Pac-Man 20th Ann. board:

- Here is a pic of the board used in the new Galaga/Ms. Pac 20th Ann. Combo game.

Here a bug is exploted to play Galaga for free (sort of):

Gallag Bootleg Board:

Here is the famous Gallag bootleg. It has is two boards, larger than the "real" Galaga, and are usually BLUE silkscreened (but not always; sometimes the CPU is blue and the Video pcb is green). There is also a credit card sized daughter board attached on the CPU board at location 4F. (Note: A Pac-Man/Ms. Pac-Man Sync Buss Controller daughter board can be used on a Gallag bootleg.) Next to the edge connector there is a marking "DG-09-2". There is also a small 5 pin video connector on the video pcb. Pinouts for this board set is different from the Midway and Namco version.

Gallag JAMMA Board

In 2002 a remake of the Gallag bootleg with JAMMA edge connector hit the market. The screen displayed "© SEOUL 2002". Some or all of these boards where populated with OLD/USED components.

Galaga JAMMA Board

Shortly after the release of the 2002 Gallag bootleg remake another Galaga JAMMA Bootleg Board was out.

Nebulous Bee Bootleg Board:

And finally here is yet another bootleg Galaga pcb known as Nebulous Bee.
Here are pics of both the CPU and the Video boards.

Fantastic/Brazilian Galaga Bootleg Board:

Here are pictures of the 'Fantastic' board and is rumored to come from Brazil as the language is Portuguese. The daughter card on the CPU board has the Taito logo with 'PCB SOM FANTASTIC'. The CPU has a decal with 'TAICORP' and a number 6-085-10052 screened on the PCB. The number on the video PCB is 6-085-10051.

Fantastic Galaga CPU PCB 
Fantastic Galaga Video PCB

Sidam Galaga Board:

Here we have a sidam licensed? Galaga pcb. This board was manufactured in Italy along with numerous other licensed games from Atari and others.

sidam Galaga CPU PCB 
sidam Galaga Video PCB

Atari Galaga Board:

Another unknown Galaga PCB found appears to be... Atari hardware? Perhaps licensed by Atari for other markets such as the UK or Australia. The only markings on the CPU board is 'MGG-703A' and the video board 'MGG-703B'.

Galaga CPU PCB 
Galaga Video PCB