Galaxian – “Dead”

Purchased described as “dead”. Started by creating a JAMMA adapter (I hate creating adapters, it is tedious work). Well, the description was correct – she is dead alright: screen has static garbage and required some tweaking to sync correctly on my test bench monitor.

Watchdog is barking, disabling it has no effect on the screen’s contents. Board already had some previous work done in it, solder-side contains more than 20 jumps to connect some RAMs back onto the bus. The Parts side shows the missing/removed/blown traces being jumped.

Started by checking the daughterboard, seems OK. Next I remove, socket and replace the 74LS245s on the board because word has it that they tend to be the cause of most problems, the Galaxian Trouble Shooting Logic Board manuals lists similar symptoms connected to those chips, and the Fluke 9010 troubleshooter says that the address lines are tied. Other than that, I cannot come up with a good way to check them! 🙂

Gotta wait for some replacement sockets and chips to come in…

Continue reading Galaxian – “Dead”

PAC-MAN (Midway, single board)

Board 1


Flashing “1” in corner of screen. Took a look at the Pac-Man troubleshoot by picture guide and that pointed me to “4R video RAM bad”. Swapped it, no good!

Tried swapping other RAMs, no change either. Started pulling all socketed chips and found a bent pin on the ROM at 6E! straightened it, and reinserted, Pac lives once more.

That will teach me to try the simple checks/fixes before the more complex ones…

Solution: Fixed bent pin on a ROM chip.

Board 2

Game would boot normally, but would then start getting random lines/glitches through the screen after running for a couple of minutes; they did not otherwise effect gameplay. Immediately suspect video RAMs, start hitting ’em with the freeze spray and sure enough, got a bad one. Replaced it, and all is well!

Solution: Replaced bad RAM chip.

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