Long time no write! It’s been busy prepping for a move and taking care of my kids by myself during the week so I haven’t had much time to write or work on my games. I did manage to stay up tonight so I can work on my Twilight Zone some more. I bought the brand new reproduction 10 Opto PCB by Great Lakes Modular. What an excellent board and I am all for LEDs for diagnostics in games.
I have this issue where if I play the game eventually U20 on my CPU board fries. Something appears to be shorting voltage through the switch matrix and frying this chip. I have been on a wild goose chase for a while now trying to find where in the world this short would be. Prior to installing the new 10 Opto PCB I had to do some ground checking to make sure I don’t fry my nice new board. After all of that checked out (after adjusting my testing methods a bit 
) I proceeded to start testing the optos.
Well I’ve found an interesting problem. I noticed that with the playfield up the center metal ramp’s opto pair wouldn’t register. I lowered it to continue testing and I rested my arm on the siderail and put my finger between the opto pair to see if it registered. I touched something and WOW a huge shock. I’m thinking what in the world did I touch… so stupid me recreates the scenario and gets shocked again
Turns out that the center ramp is electrified! With the game on I touched my negative DMM lead to the siderail and the other to the ramp.
74.1 Volts!
That’s 74.1 volts! I turned the game off immediately and started looking for a short somewhere around that ramp. I put the playfield down and touched it again, and it is still electrified! I completely removed the game from power. In a moment of humor I pulled out my Fluke 80k/40 I use to discharge monitors to discharge the game Somehow it seems the driver board is feeding electricity through the entire game. What should I check next?
Discharging my game LOL
