Brian E. Brzezicki
Copyright 2013
Version 1.00 11/06/2013

Disclaimer
Use this at your OWN risk, do NOT sue me if it breaks your board... if your doing this your board is probably already broken though ;)

Here is troubleshooting information for galaxian

Game Board #1 11/6/2013

Problem:

  • Game sprites and tiles have wrong background colors in some places

Troubleshooting/dianosis steps:

  1. Testing RAM range with Fluke 9010A, OK
  2. Pulled out ROMS, found graphics ROM at L1 with broken pin, reburned ROM
  3. Game works!
Game Board #2 11/19/2013

Problem:

  • Game is dead, nothing on screen

Troubleshooting/dianosis steps:

  1. There is no clock signal
  2. replaced crystal, and 7404 @ E1 (odd the schematics call for a 74LS386, but the board had a socket in there with a 7404 shifted one row back, does look liek the 74386 is just a tri state version of the 74LS04.
  3. Game works!
Game Board #3 11/19/2013

Problem:

  • Game is dead, nothing on screen

Troubleshooting/dianosis steps:

  1. Pulled off ROMs and CPU
  2. Turned on and noticed There is no clock signal
  3. noted E1 was socketed, removed and reseated 7404 @ E1.
  4. Now have image and garbage tiles
  5. Noted Z80 had a broken pin, replaced and reinstalled
  6. Got ROM error
  7. Read roms, found rom w on the daughterboard was bad, burned a new image on a AM2716
  8. Game works!
Game Board #4 7/8/2014

Problem:

  • Board sold to me, non-working
  • Board is missing ROMS
  • Board is missing Z80
  • Capacitors on the board have physically ruptured

Troubleshooting/diagnosis steps:

  1. Removed old capacitors, installed new ones
  2. Removed all ROMS, read ROM contents and verified, found 2 bad ROMs of the existing ROMs and 3 good ROMs.
  3. Performed my daughter board bypass / ROM minimization at http://www.arcade-cabinets.com/board_hacks/galaxian
  4. Replaced the Video ROMs @ LK1 and JH1
  5. Verified ROM ranges fluke signatures match what they should be
  6. Tested RAM long 0x4000 - 0x43FF (2114s at 7P and 7N)- OK
  7. Tested RAM long 0x5000 - 0x53FF (2114s at H3 and F3) - BTS error 04, Tested RAM long 0x5800 - 0x58FF (2101s at F4 and F5) - BTS error 04. This is unlikey that these seperate RAMS failed in the exact same way.. suspect IO/VRAM bus buffer (74LS245)@ B9
  8. Noted also that the 2114 RAMs at H3 and F3 had had sockets installed, indicating someone else previously noted a RAM error and tried to fix by replacing these RAMS, but more than likey it wasn't actually the RAMs that were bad.
  9. Removed old 74LS245 @ L9 and resocketed, installed new 74LS245
  10. Tested RAM ranges 0x5000 - 0x53FF and 0x5800 - 0x58FF - OK
  11. Installed new Z80A CPu to replace the missing one
  12. Game Works!
Game Board #5 7/8/2014

Problem:

  • Board sold to me, non-working
  • Board is missing ROMS
  • Board is missing Z80
  • Capacitors (power) missing

Troubleshooting/dianosis steps:

  1. Removed all ROMS, read ROM contents and verified
  2. Put ROMs on daughtercard, noticed some ROMS did not verify right with Fluke signatures. Odd as if I put them in socket 7L and used the associated ROM address range (0x2000 - 0x27FF) they did work.
  3. Tried Fluke RAM tests on RAM range 0x4000 - 0x43FF - got back DCD error bit 9 (address decoding), tried RAM range 0x5000 - 0x53FF - got back same DCD error (address bit 09)... the chances of TWO seperate RAM bank with the SAME decoding error only points to one thing.. Address BUS buffer. Found the address bus buffer was a 74LS367 @ 7D, replaced
  4. Noticed that my Fluke was often having power failure errors on the Z80 socket. replaced the 40 pin CPU socket.
  5. Tested RAM long 0x4000 - 0x43FF (2114s at 7P and 7N)- OK
  6. Tested RAM long 0x5000 - 0x53FF (2114s at H3 and F3) - OK
  7. Tested RAM long 0x5800 - 0x58FF (2101s at F4 and F5) - OK
  8. Was is the z80 socket or the 74LS367? the 74LS367 was really rusty.. probably was that.
  9. Now game come up with the wierd starfield screen and keeps resetting.
  10. Still working on game
Game Board #6 7/19/2014

Problem:

  • Game does not play
  • Board shows lines all throught the game

Troubleshooting/dianosis steps:

  1. Pulled ROM daughterboard, replaced with known good daughterboard, game works but has lines through the middle.
  2. Replaced the graphics ROMs with known good ROMs, made all the lines but one go away.
  3. Desoldered graphics ROM sockets, installed new sockets
  4. All lines are now gone.
  5. Pulled original graphics ROMS, found one bad (JH1) burned new TMS2517 with appropriate ROM image
  6. Now replaced known good board ROM daughterboard with original daughterboard.
  7. Pulled each ROM off of the daughterboard and verified in EPROM reader/burner. Found bad ROM in position U. Replaced with spare ROM from spare parts.
  8. Game is booting but endlessly looping with ROM error.
  9. Used Fluke 9010A to verify ROMS from the CPUs perspective. Found all ROMS good except ROM in position Z
  10. Pulled ROM in position Z, found 2 legs had broken off during removal and replacement.
  11. Burned a new EPROM and installed in ROM slot Z
  12. Game Works
Game Board #7 8/25/2014

Problem:

  • Game resets, when in test mode gives the error "BAD AA 2"
  • Previous owner stated they used to get a "BAD RAM 2" error after replacing the RAM they got this error

Troubleshooting/dianosis steps:

  1. Probed for shorts and continuity on the chip sockets the previous owner replaced.
  2. Found a tiny cut in the trace between the trace and the pin solder joint, no continuity
  3. Removed sockets and replaced
  4. Game boots up with lines though the screen.
  5. Noticed some damage to the socket ROM on one of the graphics ROMS.
  6. Pulled out ROM the leg was broken off, there was a repair attempt on the leg
  7. Removed socket, and replaced
  8. Repaired broken leg on ROM chip
  9. Game Works
Game Board #8 10/12/2015

Problem:

  • Game is missing many chips including CPU and ROMs

Troubleshooting/dianosis steps:

  1. Replaced CPU
  2. Replaced game ROMS with my GALAXIAN-DB-R daughter board replacement ROM kit
  3. Game boots and plays but rack sounds are bad, just constant tone
  4. touching pin #4 of 8R, 8S, 8T in self test mode just made constant sounds
  5. Replaced Q1, Q2 with 2N3906 replaced 555 timers @ 9R, 8R, 8S, and 8T, game works!
Game Board #9 10/16/2015

Problem:

  • Game is color for certain ships (the 2nd ship shown in attract mode) and the top ship of the board during play

    Troubleshooting/dianosis steps:

    1. This is usually due to a bad 74LS201 RAM @ 1S, pulled that chip and replaced, no change
    2. noted that the data in input on pin #13 of 1S is never getting a signal
    3. traced that pin back to 2R, which tested fine.
    4. Traced back to 2S also fine
    5. Traced back to 3P, which shoudl be putting out a signal on pine #8, no signal, however looks like one of the inputs to 3P (#9) is stuck.
    6. traced pin #9 @ 3P back to a a 74LS377 @ 6P which is feed from a 75LS175 @ 6R, this tested bad, pulled the 74LS175 @ 6R and replaced
    7. Game works!
Game Board #10 10/26/2015

Problem:

    board boots up but fighter is split into multiple parts, when the attackers get to a certain point the swarm splits into 2 parts on the screen

    Troubleshooting/dianosis steps:

    1. Found a bad 74LS283 @ 4N, replacing fixed the split sprite issues.
    2. Explosions sounds are missing when the fighter gets hit
    3. starfield is missing
    4. signal is getting through for the explosion, but the "noise" signal @ 7R pin #5 never gets through
    5. chip a1 and b1 both effect BOTH the starfield and the noise signal so there's a good chance one of them is bad
    6. replaced both no change
    7. noticed on schematic that the 7474 @ 2D also effects both the starfield and the "noise" signal
    8. replaced the 7474 @ 2D with a 74LS74 and explosion sounds and starfield are back
    9. game works!
Game Board #11 2/6/2016

Problem: Colors across where sprites should be

Troubleshooting/dianosis steps:

  1. installed new sockets on the video ROMS
  2. tested EPROM, found L1 was bad, replaced
  3. Game works!
Game Board #12 8/23/2016

Problem: Starfield is moving too fast and erratically

Troubleshooting/dianosis steps:

  1. replaced bad 74LS164 shift register @ A1
  2. Game fixed!
Game Board #13 8/24/2016

Problem: Game does not boot at all Someone installed my single ROM hack but replaced hte socket with a machined socket, some pins not fully connected

Troubleshooting/dianosis steps:

  1. Removed single ROM, replaced with socket, re-installed new single ROM board
  2. Now game boots up with graphics issues
  3. removed video ROMS, removed and replaced sockets
  4. ROM @ J1 tested OK
  5. ROM @ L1 tested bad, replaced fixed graphics issues somewhat, still have lines through graphics, and am missing shots
  6. removed all video ram 1N - 1T graphics went back to normal, but no "shots" that was unexpected
  7. I though I'd lose all sprites but did not, and color lines disappeared.
  8. found bad RAM creating weird color lines
  9. one video ram went bad, caused solid colors on everything.
  10. replaced RAMs, colors OK still have not "shot"
  11. no coin up or game start sounds
  12. replaced 74ls273 @ 9J and 74ls161 @ 8k, no change.
  13. replaced 74LS161 @ 9K, fixed sound issues.
  14. still missing "fire" sprite. looks like a dot is there at the top of the screen that follows the shooter, that must be the "missle" but the placement must be messed up.
  15. This site http://www.macros-arcade.com/galaxianfix.htm has great info regarding galaxians, that issue is one of the listed issues.
  16. it's got to be a counter at 4r or 5r one 161 was a Ti chip, one was a Signetics chip, so I pulled the signetics as they usually seem to be bad! it was the right choice.
  17. odd I noticed when de-soldering often bad chips will heat up super fast to the touch.
  18. I don't have a lot of 161 but I do have alot of 163s schematics say 161 or 163 will work, let's test that theory ... it does!
  19. Game works!