SNES AV composite cables aren't working. Please help kind people

So I recently had the desire awakened in me to revive my old consoles, put my collection on display and whatnot. Humble though it might be, I have to start somewhere right? So I decided to try to start with my SNES and get that working.

Now in years prior I have played this console with the RF cable, which is less than optimal, so I decided to try to use the AV composite cables for my old gamecube instead (Im not sure if this machine even came with its own composite cables). The cable plugs in fine, and the cable itself works fine (I tested it with the gamecube), and the SNES SHOULD work fine (playing with the RF cable still produces sound and picture) but alas the composite cable leaves the TV black as night.

I believe some sort of signal is getting through, there is a small pop in my speakers when I power on the console but aside from that there are no life signs at all. What could be the cause of this? I searched around the internet for a while and it seems maybe it could be oxidation on the pin connectors hampering the signal? I dont think the guts have ever been cleaned but as I said, the RF cable still produces playable picture and sound. Either way I'm getting ahold of the tools to open up the console first thing tomorrow morning and I'm going to open it up and take a look, and clean it. But does anyone have any insight they could share? Also any resources online where I could read up on this stuff would be greatly appreciated.

Worth noting is that it is the PAL version of the console and the cable has a scart adapter at the end of it.

i feel you i own multiple retro consoles and it kills me to have one die. have you tried to replacing the cable? another thing is you have to have a cartridge in or else it wont show anything. i hope this helps

Early skus of the SNES did in fact come with composite cables but they were apparently removed later on as people just didn't use them. I remember my dad had both the composite and RF connected on ours despite us only thinking we could access the signal via the RF method...something which led to confusion when I got my N64 as I had never accessed the input connections on our tv or any tv for that matter and thought the system was busted when the picture didn't appear on channels 3/4. The cables were supposedly so rare when I sold my SNES collection at a pawn shop in early '96, I got $30 for them alone.