So I found the ground problem. It was the HDMI connector.
Still have the same problem. No HDMI output, but input from the neo geo registers.
No green led. Other than that it seems to work, is there any scenario under which my tv’s are not supported? One is from 2008 the other 2011.
Also quick q on the tvs diodes – how essential are they and could bad connections there be the problem? In reading up the diodes are for esd protection of the chip only.