Mystic Warriors Repair Logs
Symptom: EEPROM Error
EEPROM IC tested good. A check of pin 3 showed it was shorted to ground through approx 26 ohms. Replaced the shorted 74LS273 at location 15G, reset the EEPROM data, and tested the game. The game worked but was missing text and motion graphics. Resoldered the surface mount chip at 14K to finish the repair.
Symptom: Board would start self test and stick at "RAM ROM CHECK"
Board would boot into an EEPROM test/initialization if the test button was held down when powered on but would lock up when trying to normally start. The hybrid sound module, part # 054986A was cracked into 2 pieces. Replaced the hybrid module with one from a donor board and tested the game.
Symptom: Input problems
Checked the JAMMA edge connector with a logic probe and found correct logic levels: high when button is open and ground when closed.
Checked the traces through the resistor networks and back to the 74LS257 at 19B. Logic levels were good going to the chip. Replaced the bad chip and tested the game. Found some corrupt graphics. Resoldered the surface mount chip at 14K, 14J, and one side of 8J to fix.
Symptom: RAM Failure
Self test showed that 9E, 10E, and 11E had failed. Inspected the board and found 3 bent/shorted pins on the custom IC 054338 at 10C. Fixed the pins and tested the board.