Rika24 wrote:if it were the power adapter would the light on the SEGA still turn on? because mine lights up. and yeah i use the tv just for all my gaming. i have N64, Gamecube, PS1, and PS2 in addition to my SEGA (i have an NES too that used to be my sister's, but that's in storage at the moment). all of them work with the tv.
The power light could be on, but that doesnt mean that the console is getting sufficient/insufficient power, of which can cause the issues.
One idea is if you have a local retro game store nearby, they would probably let you bring it in and test it on their AV cables/power adapter and that would let you rule out whether or not it's your console or your cables. Though it doesn't sound like it's the AV cables since you've recently purchased them from a reputable seller and have tried with multiple cables. My guess is that it's either a problem with the AV module on the board, or it's with your power adapter. Honestly, though, if you're not in the position to try and repair the board via soldering, etc. , you're probably best off just buying a new genesis, console only (preferably the HD model

When I was experiencing video issues on my genny, which ended up being due to using the wrong power adapter, I took it down to my local game shop, tested it on their AV/Power setup, it ran perfectly fine and they sold me the proper, first party sega Power Adapter right there for less than $10.