I don't know how likely it is but I had a broken trace right at one of the pins and you couldn't see it because it was covered . Try a continuity test to each pin and it's related transistors etc. not sure if it will help but worth a try .

It looks to me like D8, R47, R55 are all associated with Q72. Possibly C50 and Q81 are too but they look more like they're on the pin for CN6-1.

Pinwiki discusses a section of the lamp matrix circuitry that often has heat damage but I'm not sure if this is related to your issue.
http://www.pinwiki.com/wiki/index.php?title=Data_East/Sega#Using_MOSFETs_in_the_Lamp_Matrix_Circuitry

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It will be a day or two before I can get back to you Cosmo. Quench GRUMPY barakandl can probably help.

Not an expert by any means. But you can check the resistor R47, but should probably pull one leg up off the board, then check the resistance. Should be 1k i believe. Also your continuity should be from CN6-1 to the top leg of Q72 from what i see on my R&B. Here is a snip of the cpu diagram. Hope it helps. I would check continuity from each point. For example from the resistor to the next point etc.

CN6 (resized).JPG

The good thing about having a board issue with lamp and switch related stuff is that you can work your way through with a dmm and test the good vs the bad to see which part is not giving the same readings as the working portion. Testing resistors "effectively" within a circuit is next to 'not gonna happen'. I would check the good segment for the quantity of resistance and continuity and compare to the supposed bad segment. What is measuring off? If you find that all components are measuring the same then I would say your issue lies within the corresponding IC's. 7406 TTL chips at 11F and 12E drive the rows though a series of 2N5060 controlled rectifiers at Q81 to Q88. These also connect to the 6821 PIA at 11D.

Any solution to this issue? I have the same issue on my R&B that just started tonight after a few games.

I had a similar issue with row 4 and the culprit was D13

Thanks for the group as I was going to replace Q75 T122 but tested fine, continuity was fine, test the diode and no continuity. I carefully piggybacked a good diode on the old one and lights work. Now for a simple board repair