![]() This basically eliminated the chip from the circuit (tying the input to the output). I then was about to replace this chip and noticed that pins 8 & 9 were shorted to pin 13 by a solder blob to a trace. Well I only found that the chip didn’t seem to behave as I expected, touching the output pin 13 reset the game. I looked at IC 6B (74LS128)and check for any odd signals. When the board was cold, the reset line was high, sort of, with a lot of noise riding on it. I then traced the signal back to the reset switch, POR circuit, and the final output to the Z80s. ![]() I first looked at the *reset lines at the Z80 CPUs after the game would no longer come up and found that reset was held low. I first tackled the reset problem since after awhile the game would not come up at all. The reset problem got worse as the board warmed up, but the video failures got better, go figure. This Galaga actually had two problems, the intermittent resets and bad/garbaged video. Adding jumper wires to the video PCB from the main PCB fixed this problem (+5V and GND).Ĩ/17/00 Galaga that would intermittently reset This problem was due to low +5V going to the video PCB. The other problem was that the starfield would first simply be a snowstorm then they would disappear altogether. In messing with the ROMs I have matched up some others. I found out by simply swapping ROMs for known good ROMs from my board it was ROM G7. This sounded like an easy one except which ROM is ROM 11? In Galaga (Midway) it is 3J. Archived from an old cache page from a GeoCities page…ġ1/25/00 Gallag with a ROM 11 error and loss of starfield
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