Mario Bros. no power to board?

Chupperson

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Donor 2016
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I've been working with a Mario Bros. cab recently, and just got done replacing the audio chip and recapping the monitor. Everything was working perfectly. Today I turned it on and it makes the regular squawk when you turn it on, but there's no video and it doesn't advance the counter when you put in a coin. It doesn't have a white screen... it just looks like the monitor is on with no input. This happened once before, but I checked the wiring harness and all the molex-type connectors from the front of the cab, and then it turned back on just fine. Is there a power LED on the board? I don't see anything when I turn it on. Could it be a voltage issue? A wiring harness issue? Any ideas where I should check?
 
may or may not be helpful, but a friend of mine had a dead Popeye and I brought it back just by reseating the plugs on the power block.

you can see if you're getting voltage to the board by measuring voltage at one of the small ICs. I have a picture of the points in the PSU guide in my signature.

I'm not sure off hand if Mario Bros. uses -5V for anything, I wanna say Popeye was the only one that was +5 only..?
 
No power led on the board. Could be a loose pin in the edge connector or cold solder joint on the PS if it happened before, or as suggested above could be the start of the PS getting flakey and putting out low voltages.
 
Ok, so I checked the voltage at the power supply and it was good. I checked voltage on some of the logic chips and I was getting +5v. Still couldn't get it to work. Then I flipped all the DIP switches up and down once just for the heck of it, and then I turned it on and this monstrosity happened for about 20 seconds:

https://www.youtube.com/watch?v=El0Z5ZJIplg

Everything was going at once, including the credit counter clicking.
Now it works fine again. ???
 
that almost looked like a CPU thing. you apparently have power sorted out, now your next goal is hunting around the socketed chips and checking for corrosion. now might be a good time to give the sockets a deoxit bath with a toothbrush for added measure. if the chips have corrosion (white stuff, green stuff, black stuff; anything that makes the legs not look silver) then you can sand it off gently.
 
I tried to play it again tonight and it once again didn't start.
The CPU had some bad oxidation on several legs so I gently scrubbed it with a plastic eraser until it looked clean.

I also sprayed Deoxit in the sockets of the CPU and the two other chips that aren't EPROMS or the sound chip. When I turned it back on, it did another freakout similar to last time but didn't proceed to work.

I've discovered something really odd though. It seems that when I change the DIP switch settings, each one causes a different sound from the game to play when I turn it on. So switch 1 plays the "start new life" fanfare, switch 2 plays a different one... when I turned on switch 7 and 2 at once, it played two sounds. It still doesn't start the game.

Could the CPU be dying?
 
I'm assuming that the DIP switch sounds are in fact intentional?

Anyway going off an idea from another thread I decided to turn the game on today since the weather cooled off last time I turned the game on. Today was warmer and... the game works again. So there could be a temp sensitive chip on the board... but I guess I need to get a logic probe so I can test the next time it doesn't start.
 
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