So I reseated the pcbs on VF3. First attempt I noticed one was really not plugged in well at all on the side, turned it on and got characters but that were mostly gray.
Reseated gently the ones in the back of the stack and boom! Finally seeing characters. All graphics appear to be working now.
However, my coins are not being detected when using Lemonys power adapter and the test button on my Blast City cabinet does not work.
I switched over to test with the VF3 Blast City Harness and test and service buttons worked and I was able to register coins that I inserted.
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Other things I'm perplexed about are dark levels are really really dark, there is a loud buzzing sound from speakers on Blast City or Sun PSU power, and the sounds are kinda faint and washed out.
Certain punches and kicks are bearly audible while other sounds like the sound-effect right before a level starts are clear as day. The announcer is also really hard to hear.
I had a Mistercade in my Blast Previously and Naomi 2 Net Dimm and had no crazy loud buzzing or major sound issues.
I believe they have Model 3 Sound Amp boards but not sure if that would be worth exploring?