Lady Bug

Screen filled with coloured lines, unstable, no sync (see above) – check clock signals from horizontal and vertical scan generators (74161’s at 2R,2S,3R,3S) – no signal feeding into pin 2 of horizontal generators. Follow trace back to 7474 at 3N, signal going in, nothing coming out – replace chip and screen display back to normal….

Blank screen, Blanking line to output colour proms always enabled. Trace back to 74161 in timing circuit – output stuck, input clock all look OK – replace chip and picture appears. Blue video only – The video lines are controlled by three transistors near the edge connector, checking these revealed that 2 were not giving…

Glitched graphics. Screen changes as board is flexed. Moved around board pressing chips until pressing the custom surface mount chip at B6 changed the effect. Noticed that the corner most pins had come up from the board. After an unsuccessful effort to resolder them, I used some enameled 38 swg wire to solder from the…

Crashing game. Game woud start attract mode, but shortly after would crash and boot loop. Entering test mode (hold player 1 start button whilst switching on) and it would pass first time around, but fail at random addresses on subsequent runs. The /WAIT signal on the main Z80 is handled by the IC at E2…

Ran through self test OK, came up with chequer board screen and then reset most of the time. Occasionally would start game, but with credit noise continually playing and credits rapidly counting upwards. This is caused by CPU 4 (E5) not running properly. checked the eprom and ram (C5,D5 and E5) and ram was faulty….

One of the guns on a Time Crisis 2 was no longer registering shots on the screen. Following checks on wiring, cleaning lens, etc. it appeared that the optical sensor (opto) was dead. This is a small PCB in the gun, 2421961100, pictured above. I couldn’t find any schematics or information about the parts used,…