I am trying to fix a system 11b game. The mpu is from a cyclone being used in a swords of fury. The board is super clean and the batteries removed except for U10 which was replaced (not socketed) and looks like crap (dirty flux, damaged pads)

Using a bench power supply so 5 and 12v are good.

On the bench I get a 5V led and nothing else. I was able to read the roms and they didn't match the files online so I burned new ones. No change

I tested the cpu and it tested fine, couldn't test the ram as it is not socketed.

Clock is present and looks normal. Reset looks correct.

Fixed a nasty PIA replacement at U10 and replaced the ram per clays guide. No change.

Put in Marco Albus' test rom and the led lights and stays lit. I assume this means it's not running.

Any suggestions where to go from here?

I am not totally sure what worked but here is what I did:
1. Leon said replace the cpu with a 6808. I have a known good so I did, no change.
2. I wanted to make sure the ROM sockets were good so I gave it the tug test. Seems fine
3. I wanted to verify I am not using the test rom incorrectly so I pulled it and used the new game roms in it!

It boots! I'll get a display hooked up to it and put it through the paces now.

Update, think this might be a socket issue. Put the Marco Test rom back in and nothing. Got it to work once and everything was fine. Then I put the game roms in and got 10 blinks which is a U27 checksum error. Reseated U27 and it worked. I'll replace the socket and see if that fixes it

2021-04-12 07.38.14 (resized).jpgAnd here's the problem2021-04-12 07.38.11 (resized).jpg

Everything around it looks great. I wonder if the board was cleaned but the sockets not replaced