Sega Blast City, coin mech stopped working (fixed)

[K405]

Maybe someone here has some advice for me. So I have my Sega Blast City upstairs now and decided it was time to try out the CPS2 multi kit with it. Something strange occurred after I played. At the next 'boot' I got a humming loud noise over the speakers but could hear the source music way in the 'back'. Started googling and concluded I had blown my audio amplifier because I hooked up the separate RCA connectors to the CPS2 mobo which apparently kills the Jamma mono audio amp. After leaving it for a day and trying again sound was working fine again. Only thing not working anymore now is the coin mech, when I pull the little metal lever nothing happens, this was working before, credits were topped up. When I pull pin 16 (JAMMA Coin) to GND I do get a credit and the coin meter flips as well. So I measured continuity in the coin switch and that's OK. But here's the part what I don't get and doesn't make sense to me at all.

When I measure GND from the JAMMA Harness Connector to Pin 7 on CN 9 , multimeter beeps
When I measure Pin 7 on CN 9 to GND side of the coin mech switch , multimeter beeps
When I measure GND from the JAMMA Harness Connector to GND side of the coin mech switch , no connection!

So blue and green are OK but measuring from red to red is NOK!

Hope it's a bit clear otherwise forgive me

 

[K405]

This was actually really funny/stupid. So I measured continuity from the JAMMA edge connector to the connector on CN9 on the connection board, all fine. Then from CN9 to the end of the coin mech switch, all fine. Then from the JAMA edgde connector directly to the end of the coin mech switch, NOK. Not connected.. It turned out to be a loose connection in the CN9 (JST VH) connector itself! Couldn't believe my eyes Whenever I was measuring I was applying pressure on the connector with the multi-meter probe which restored the connection which made it look ok, hehehe.

I jammed a small metal screwdriver in the back and the end to end connection measured fine now, from the JAMMA edge connector to the coin mech switch. So I permanently fixed it by chucking in a small piece of wire and sealing it with some bluetac. Happy I got it working again.

Still need to remove those nasty soda pop stains.