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
- Removed single ROM, replaced with socket, re-installed new single ROM board
- Now game boots up with graphics issues
- removed video ROMS, removed and replaced sockets
- ROM @ J1 tested OK
- ROM @ L1 tested bad, replaced fixed graphics issues somewhat, still have lines through graphics, and am missing shots
- removed all video ram 1N - 1T graphics went back to normal, but no "shots" that was unexpected
- I though I'd lose all sprites but did not, and color lines disappeared.
- found bad RAM creating weird color lines
- one video ram went bad, caused solid colors on everything.
- replaced RAMs, colors OK still have not "shot"
- no coin up or game start sounds
- replaced 74ls273 @ 9J and 74ls161 @ 8k, no change.
- replaced 74LS161 @ 9K, fixed sound issues.
- 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.
- This site http://www.macros-arcade.com/galaxianfix.htm has great info regarding galaxians, that issue is one of the listed issues.
- 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.
- odd I noticed when de-soldering often bad chips will heat up super fast to the touch.
- 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!
- Game works!