Stuck - MCR Tapper

[bobn]

I have fixed alot of games but this one has really thrown me for a loop. Perhaps I can find some help here. The frustrating thing is I had a working game until I decided to throw in a new vision pro monitor. I replaced the monitor and wired it before the power brick since it does not require an isolation transformer. I powered up the game to a nearly perfect picture. I went to coin up the game and had no luck. I flip the test switch and all inputs (both coin mechs, all control panel functions) show working when I activated each control. The only two things that will not work when in game mode are both coin mechs and the service switch. Weird that each test working in test mode but not in game mode.

When I got the machine it was already partially wired to both the original linear power supply as well as a switcher. Since this problem I have since moved everything to the switcher except for the reset circuit which is still connected to the linear power supply. The reset circuit appears to be functioning correctly. I do not have any of the speaker hum that most compain of when running a switcher in a mcr game. The sound works 100% though I do get the "sound board timed out" message at boot up. I also replaced all the ribbon cables with ones sold by Bob Roberts. I have tried all sorts of different grounds and made efforts to isolate the anolog ground as well as reseating all removable roms.

I will update this thread as this repair moves forward. Any suggestions are appreciated.

Game: Tapper
Problem: Will not coin up in game mode