Attempting to get a Monte Carlos to boot and could use some guidance.

I went ahead and tied all grounds together at the transformer and did away with the wonky ground connection.

I put new .156 headers in the 5v psu and repinned the connections there. Power supply adjusted and putting out stable 5vdc.

I pulled the mpu and lightly cleaned the connection pads with a fiberglass pen.

When I power up the game I get some GI lighting and nothing else. No displays and/or sound.

Looking at the mpu I'm not seeing any lighted indicators or any other feedback.

The power connection to the mpu reads 4.9vdc. The Panasonic battery pack tests at 4.2vdc.

One time I got a slow steady red flashing led on the sound board.

So with no display or any other activity how do I approach this?

Spent a little time rooting around the machine today.

I removed the reset card as recommended.

Someone on a fb group mentioned they had an 80b that wouldn't boot without balls loaded so I did that.

I pulled the rom on the daughter card to inspect. Legs all solid and no corrosion. Re-installed the rom.

Verified voltage at the display and its getting good voltage.

No change.

I'm going to pull the mpu and take a closer look at the daughter card tomorrow.

Pulled the mpu to reflow the daughter card connections. Found a lot of sketchy joints. Reflowed quite a few.

Also pulled and inspected the sound board. Same story handful of not so great joints that got reflowed.

All that done, no change.

Why verifying the 12v power to the sound board I set my meter on the playfield. Noticed I had a vdc reading.

Probed around the playfield and found most metal parts to have voltage present. Mostly small amounts, 0.8-1.4. But found the shooter lane ramp was kicking 4.3vdc. Wtf?

So is this more grounding issues?

Yes I have 2 eproms with a clear window.

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